Open access Protocol

BMJ Open: first published as 10.1136/bmjopen-2019-031327 on 21 November 2019. Downloaded from http://bmjopen.bmj.com/ on November 29, 2019 at UNB - Universidade de Brasilia.
Efficacy of a mindful-­eating programme
to reduce emotional eating in patients
suffering from overweight or obesity in
primary care settings: a cluster-­
randomised trial protocol
Hector Morillo Sarto,1,2 Alberto Barcelo-­Soler,1,3 Paola Herrera-­Mercadal,1,3
Bianca Pantilie,4 Mayte Navarro-­Gil,1,3 Javier Garcia-­Campayo,1,3
Jesus Montero-­Marin1,5

To cite: Morillo Sarto H, Abstract

Barcelo-­Soler A, Herrera-­ Strengths and limitations of this study
Introduction Little is known about the applicability of
Mercadal P, et al. Efficacy of mindfulness-­based interventions in Spanish adults with
a mindful-­eating programme ►► This study is going to lead the first intervention
overweight/obesity. The objective of the present study
to reduce emotional eating based on mindful eating applied to overweight and
protocol is to describe the methods that will be used in a
in patients suffering from obesity in the Spanish primary care (PC) context.
overweight or obesity in cluster randomised trial (CRT) that aims to evaluate the
►► It will open new perspectives about current recom-
primary care settings: effectiveness of a mindfulness eating (ME) programme to
mendations included in the clinical guidelines for the
reduce emotional eating (EE) in adults with overweight/

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a cluster-­randomised treatment of these conditions in Spanish PC settings.
trial protocol. BMJ Open obesity in primary care (PC) settings.
►► It will carry out a long-­term follow-­up using both bi-
2019;9:e031327. doi:10.1136/ Methods and analysis A CRT will be conducted with
bmjopen-2019-031327
ological and psychological assessments to analyse
approximately 76 adults with overweight/obesity from
changes that the treatment may produce.
►► Prepublication history for four PC health centres (clusters) in the city of Zaragoza, ►► The sample size used will be a main limitation, be-
this paper is available online. Spain. Health centres matched to the average per capita cause it has been estimated based on foreign works
To view these files, please visit income of the assigned population will be randomly due to the lack of previous studies in the Spanish
the journal online (http://​dx.​doi.​ allocated into two groups: ‘ME +treatment as usual (TAU)’ context.
org/​10.​1136/​bmjopen-​2019-​ and ‘TAU alone’. The ME programme will be composed
031327). of seven sessions delivered by a clinical psychologist,
and TAU will be offered by general practitioners. The
Received 01 May 2019 Background
primary outcome will be EE measured by the Dutch Eating
Revised 19 September 2019
Behaviour Questionnaire (DEBQ) at post test as primary According to WHO, overweight and obesity
Accepted 24 October 2019
endpoint. Other outcomes will be external and restrained are disorders in which there is abnormal or
eating (DEBQ), binge eating (Bulimic Investigatory Test excessive fat accumulation in adipose tissue
Edinburgh), eating disorder (Eating Attitude Test), anxiety that can be harmful to health.1 They are
(General Anxiety Disorder-7), depression (Patient Health defined operationally as a body mass index
Questionnaire-9), mindful eating (Mindful Eating Scale), (BMI)—weight in kilograms divided by the
dispositional mindfulness (Five Facet Mindfulness square height in metres (kg/m²)—from 25
Questionnaire) and self-­compassion (Self-­Compassion to 29.9 and ≥30 kg/m2, respectively. WHO
Scale). Anthropometric measures, vital signs and blood
estimated that, in 2014, 39% of adults world-
tests will be taken. A primary intention-­to-­treat analysis
on EE will be conducted using linear mixed models.
wide were overweight (approximately 38%
Supplementary analyses will include secondary outcomes of men and 40% of women), and 13% were
and 1-­year follow-­up measures; adjusted models obese (approximately 11% of men and 15%
© Author(s) (or their controlling for sex, weight status and levels of anxiety of women).2 In absolute terms, it is estimated
employer(s)) 2019. Re-­use
and depression; the complier average causal effect of that approximately 1 billion adults are over-
permitted under CC BY-­NC. No
commercial re-­use. See rights treatment; and the clinical significance of improvements. weight and that at least 300 million are obese
and permissions. Published by Ethics and dissemination Positive results of this throughout the world, with an increasing
BMJ. study may have a significant impact on one of the most prevalence in most countries.3 Unhealthy diet
For numbered affiliations see important current health-­related problems. Approval and the lack of physical activity are important
end of article. was obtained from the Ethics Committee of the Regional causes of obesity4 and also the most important
Authority. The results will be submitted to peer-­reviewed non-­communicable obesity-­related diseases,
Correspondence to journals, and reports will be sent to participants.
Dr Jesus Montero-­Marin; such as cardiovascular disease, type 2 diabetes
Trial registration number NCT03927534 (5/2019).
​jmonteromarin@​hotmail.​com and certain types of cancer.5 6 They contribute

Morillo Sarto H, et al. BMJ Open 2019;9:e031327. doi:10.1136/bmjopen-2019-031327 1

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BMJ Open: first published as 10.1136/bmjopen-2019-031327 on 21 November 2019. Downloaded from http://bmjopen.bmj.com/ on November 29, 2019 at UNB - Universidade de Brasilia.
substantially to global morbidity, mortality and disability psychoanalysis or hypnosis.30 31 On the other hand, it has
burden.7 Obesity has been associated with a higher prev- been established that between one and two-­thirds of the
alence of hypertension, dyslipidaemia, sedentary lifestyle, people who follow restricted diets gain more weight than
diabetes, subclinical organ injury and cardiovascular they lose.32 The degree to which restricted diets are coun-
disease,8 depression,9 migraine10 and hypertension.11 terproductive has probably been underestimated due to
Even in the Mediterranean region (in which Spain is several methodological problems, focusing on the results
located), traditionally associated with a healthy lifestyle, of successful weight loss instead of the long-­term main-
the evolution of eating habits has led to a progressive tenance of weight loss. Moreover, studies do not provide
abandonment of the traditional pattern, for example, consistent evidence that dietary restriction results in
decrease in the consumption of fruits and vegetables significant health improvements, regardless of possible
and increase in the consumption of fast food, especially weight change32; in fact, it is a significant contributor to
among the youngest age groups.12 These eating style binge eating.33 Nevertheless, changes in dietary habits do
changes have also been complemented by a physical not necessarily have associated restrictions, since healthy
activity decrease pattern and longer sedentary time.13 changes may be made to food consumption without
In fact, Mediterranean countries currently express high restriction, such as a healthy choice of food.34–36
obesity prevalence rates.14 15 The investigation of new ways At this point, a fundamental debate in the field has
to treat this problem in the primary care (PC) context is been the consideration or not of weight loss as a main
developing successfully, although incipiently, throughout outcome.37 Weight is a very simple measure that is not
virtual platforms that allow for the training and interac- always directly related to the interaction that a person
tion of different professionals.16 The most common users has with food, because there may be other factors to take
of the PC system are patients between 45 and 75 years, and into account, such as endocrine disorders or drug treat-
precisely this age range presents a higher prevalence of ments. However, it has been observed that the consump-
overweight and obesity than other age groups in Spain.17 tion of certain problematic foods and eating behaviours,
Reducing the prevalence of obesity is not an easy task such as binge eating and eating linked to the satisfaction
because a multiplicity of factors may be involved.18 In most of emotional needs rather than the satisfaction of phys-
cases, an individualised and multidisciplinary treatment ical hunger, are related to the presence of obesity.38 In

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is recommended because of the efficiency and resource fact, our relationship with food is an important issue.
complexities that such treatment may involve.19 20 Obesity Recently, a line of study interested in promoting the
treatment is a challenge to which societies have not yet conscious choice of food, developing awareness of the
adequately responded, and the prevalence of obesity has differences between physical hunger and psychological
increased, leading to an encrusted problem.21 hunger, noticing the satiety signs and eating healthily as
There are factors on which experts agree: diet and a response to all those signals, has been developed.39 40
physical activity are fundamental pillars for the treatment Within this current stream of the literature, the ‘mindful
of obesity to achieve a ‘negative’ energy balance.22 The eating’ (ME) movement emphasises being aware of the
fundamental objective in the initial treatment of over- present moment when one is eating, paying attention
weight and obesity is to reduce body fat until it reaches to the effect that food has on the senses and taking
a level that allows for an improvement in health and into account the physical and emotional sensations in
a reduction, as much as possible, in risk factors.23 To response to the eating process.37 41
achieve long-­term maintenance of weight loss, it is essen- The first ME study42 showed that, through a 7-­session
tial to modify and establish habits related to diet, eating group programme, it was possible to reduce the number
patterns and physical activity.19 24 25 However, between of binge-­eating episodes, as well as depressive symptom-
25% and 30% of patients with obesity seeking treatment atology. The meditative practice related to eating was
to reduce their weight suffer from a marked depression the best predictor regarding the improvement in eating
condition or other psychological disorders. Thus, physi- control. Later, although a pilot study found no effects
cians or psychologists should routinely inquire about the on weight change,43 it was observed that ME produces
mood, sleep, appetite, fun activities and eating patterns of improvements in depressive symptoms, expectations of
patients with obesity. In fact, individuals with obesity with results, food-­related self-­
efficacy and cognitive control
marked depression, anxiety or binge-­ eating problems with respect to eating behaviours in patients suffering
may require pharmacological treatment and/or psycho- from diabetes.39 44 More robust studies have concluded
therapy before trying to lose weight.26 that dispositional mental awareness plays an important
Psychological treatments, mostly included in the cogni- role in eating behaviours, supporting the use of ME
tive–behavioural therapy umbrella, have shown favour- feeding techniques in diabetes self-­ management inter-
able, but not definitive, results for weight loss.27 However, ventions.45 It has recently been stated that ME seems to be
not all the studies reviewed have showed such positive an effective approach to weight and glycaemic control in
outcomes,28 29 and given the intense debate in this field, people with diabetes, and thus, promoting mindfulness
there is an evident need for more trials and long-­term could be one of several behavioural tools to support key
evaluations. Less encouraging in their long-­term results self-­care aspects to regulate glycosylated haemoglobin.46
are other psychological treatments employed, such as ME has also shown efficacy in binge-­eating disorders47

2 Morillo Sarto H, et al. BMJ Open 2019;9:e031327. doi:10.1136/bmjopen-2019-031327

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BMJ Open: first published as 10.1136/bmjopen-2019-031327 on 21 November 2019. Downloaded from http://bmjopen.bmj.com/ on November 29, 2019 at UNB - Universidade de Brasilia.
and could contribute to weight loss and a reduction in Trial design
sweets consumption and fasting glucose levels,36 although This study is a multicentre, two-­armed, parallel, cluster
only moderate effects have been found when specifically randomised trial (CRT) with PC health centres as clusters,
trying to reduce weight in the long term.48 with pretreatment, post-­treatment and 1-­year follow-­up
It has been said that ME appears to be effective in measures, and an equal cluster allocation rate between
addressing emotional eating (EE), binge eating and groups as well as equal cluster size. PC centres (ie, clus-
eating in response to external cues, with the poten- ters) in the city of Zaragoza, Spain, will be randomly
tial of improving problematic eating behaviours and assigned to two different conditions, with one psycholog-
controlling food intake.48 However, evidence of ME ical intervention group (‘ME +TAU’) or one usual treat-
training on weight is mixed and additional research to ment group (‘TAU alone’) managed by their general
determine comparative and long-­term effects is needed.49 practitioner (GP), to test the superiority of the ‘ME
In recent years, EE—that is overeating in response +TAU’ provision compared with the ‘TAU alone’ provi-
to negative emotions50—has been seen as a potential sion, considering outcomes at the individual participant
explanatory factor of the complexity of overweight and level. A CRT design will be used because the intervention
obesity.51 It has been observed that: (1) EE interacts with will be performed in PC settings and persons within the
loss of control eating, increasing disordered eating atti- same PC health centre may respond more similarly to
tudes, BMI and adiposity52; (2) EE is implicated in the the intervention than persons drawn from different PC
use of compensatory behaviours to regulate weight50; health centres—they could have more characteristics in
and that (3) decreases in EE are associated with weight common owing to the fact of sharing the same environ-
loss success in overweight adults.53 It has been suggested ment and deliverer of intervention treatment (GP).57
that ME approaches might have a positive influence For ethical reasons, those PC health centres allocated to
as adjuvant therapies for weight management and for ‘TAU alone’ will also be offered the ME programme after
the development of a more conscious eating style with finishing the trial at 1-­year follow-­up.
healthier eating behaviours.54 55 This could be achieved
because mindfulness-­ based programmes which usually
incorporates training in dispositional mindfulness and Methods

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self-­
compassionate attitudes improve emotion regula- This protocol was designed in accordance with the Stan-
tion processes,56 which in turn are inversely related to dard Protocol Items: Recommendations for Interven-
EE,51 suggesting the treatment of overweight and obesity tional Trials 2013 statement.58 The timeline of the study is
should focus on calorie-­restricted diets and on emotion presented in table 1.
regulation skills. However, to the best of our knowledge,
no studies have attempted to improve these eating vari- Participants, study setting and eligibility criteria
ables in patients suffering from overweight or obesity Participants will be chosen from the four PC health centres
using ME interventions in the Spanish PC context. of Las Fuentes Norte, Parque Goya, La Almozara and La Jota
in the city of Zaragoza (Spain). The city of Zaragoza has a
Objectives population of 663 023 inhabitants, with approximately an
The main aim of this study will be to evaluate an ME average age of 44 years, a percentage of women of 52%,
psychological intervention plus treatment as usual (‘ME an average per capita income of €11 800, a percentage of
+TAU’) to promote a healthy change in relations with emigrants of 14% and a dependency rate of 53%.59 Each
food by reducing EE in patients with overweight or obesity of the four PC health centres has an assigned population
in PC settings, compared with a control group that will of between 10 000 and 24 000 patients whose average
receive medical treatment as usual (‘TAU alone’). The age is between 41 and 46 years, a percentage of women
secondary aims will be to assess the possible differences between 51% and 53%, an average per capita income
between groups in external, restrained, binge and ME as between €9000 and €12 000, a percentage of emigrants
well as eating disorder risk, anxiety, depression, disposi- between 6% and 17% and a dependency rate of between
tional mindfulness and self-­compassion. Finally, we will 41% and 58%, and thus can be considered representa-
also explore the possible differences in anthropometric, tive of the PC health centres of Zaragoza according to the
vital sign and blood test measures to determine the scope previously described variables. Patients will be selected by
of the intervention on these physical parameters. GPs working in the PC centres (with one GP for each PC
The principal hypothesis is that ‘ME +TAU’ will be more health centre, which will function as a cluster). When the
effective than ‘TAU alone’ in reducing EE in patients GPs observe potential participants who meets the eligi-
with overweight or obesity in PC settings. The secondary bility criteria, they will be informed about the general
hypothesis is that ‘ME +TAU’ will function better than characteristics of the study, providing them with the
‘TAU alone’ to improve the levels of external, restrained, opportunity to participate. The inclusion and exclusion
binge and ME, eating disorder risk, anxiety, depression, criteria of the patients are specified in table 2.
dispositional mindfulness and self-­compassion, as well as Within the general framework of promoting healthy
the anthropometric, vital sign and blood tests physical and active lifestyles in the community, participants are
parameters. required to have two of the following three risk factors in

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Table 1 Schedule of enrolment, interventions and assessments
Study period
12-­month
Enrolment Allocation Intervention follow-­up
April May June July August September June/August
Timepoint 2019 2019 2019 2019 2019 2019 2020
Enrolment
 Eligibility form X
 Informed consent X
 Allocation X
Interventions
 ME+TAU C1(1) ‍ ‍
 ME+TAU C1(2) ‍ ‍
 ME+TAU C2(1) ‍ ‍
 ME+TAU C2(2) ‍ ‍
 TAU alone C3 ‍ ‍
 TAU alone C4 ‍ ‍
Assessments
 Sociodemographic X
 DEBQ X X X X X
 BITE X X X X X

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 EAT-26 X X X X X
 FFMQ X X X X X
 SCS X X X X X
 MES X X X X X
 GAD-7 X X X
 PHQ-9 X X X
 Weight (kg) X X X
 Waist perimeter (cm) X X X
 Vital signs (DBP, SBP) X X X
 Cholesterol (HDL, LDL) X X X
 Glucose X X X
 HbA1c X X X
 ALT X X X

ALT, alanine aminotransferase; BITE, Bulimic Investigatory Test Edinburgh; C, cluster (subgroup in brackets); DBP, diastolic
blood pressure; DEBQ, Dutch Food Behaviour Questionnaire; EAT-26, Eating Attitude Test; FFMQ, Five Facet Mindfulness
Questionnaire;GAD-7, General Anxiety Disorder; HbA1c, glycosylated haemoglobin;HDL, high density lipoprotein; LDL, low density
lipoprotein; MES, Mindful Eating Scale; ME+TAU, Mindful eating;PHQ-9, Patient Health Questionnaire; SBP, systolic blood pressure;
SCS, Self-­Compassion Scale; TAU, treatment as usual.

order to be included in the study: (1) sedentary lifestyle, will be considered when obtaining a score <5061; and the
(2) poor diet or (3) binge episodes. GPs will evaluate presence of binge episodes, using the Bulimic Investiga-
the suitability of patients for the trial in terms of their tory Test Edinburgh (BITE)—with a cut-­off point of two
age and overweight/obesity condition, ability to under- binge episodes in a week.47
stand Spanish and willingness to participate in the study. Exclusion criteria were derived from the typical criteria
A psychologist assessor will assess the level of physical used to rule out patients in this type of study, including
activity, using the International Physical Activity Ques- serious mental illness, acute-­phase depression, schizo-
tionnaire—a sedentary lifestyle will be established in case phrenia or psychotic disorders, drug abuse or depen-
of a low level of physical activity60; a possible poor diet, dence and medical conditions that make it difficult to
using the Diet Quality Index-­International—a poor diet participate in the intervention.62–64 These exclusion

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Table 2 Inclusion and exclusion criteria
Inclusion criteria Exclusion criteria
►► Age between 45 and 75 years ►► Any diagnosis of a disease that may affect the central
►► Overweight or obesity condition (individuals with BMI ≥25) nervous system (brain condition, traumatic brain injury,
►► Two of these three risks: sedentary lifestyle, poor diet or dementia, etc.)
binge episodes ►► Other psychiatric diagnoses or acute psychiatric illness
►► Ability to understand oral and written Spanish (eg, substance dependence or abuse, schizophrenia or
►► Willingness to participate in the study and sign informed other psychotic disorders), except for anxiety or personality
consent disorders
►► Presence of delusional ideas or hallucinations whether
consistent or not with mood
►► Suicide risk

BMI, body mass index.

criteria will add proper functioning to the intervention that the home tasks were too difficult to be carried out
groups and also patient safety, avoiding possible exac- during the programme. Due to the good participation
erbations of psychosis, mania or suicidal ideation.65–67 and feedback obtained, and considering the difficul-
Anxiety or personality disorders will not be excluded ties reported, we decided to continue working on this
so as not to bias the selected sample, because they are research line involving patients and GPs. Following the
particularly related to eating disorders.68 69 All in all, an comments of the pilot participants, we adjusted the orig-
adequate monitoring through the study will be carried inal programme length down to seven sessions, and also
out regarding the safety of all patients (described next). If lightened the homework load.
patients are interested in participating, they will be asked The individual results of the present study will be
to sign a written informed consent form. Patients who do shared by email with the corresponding participants who

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not accept participation will be treated in their PC centres express their desire to know the results. The resulting
as usual due to ethical reasons. publications will also be disseminated to participants,
and a free lecture of a summarised report, once the study
Patient and public involvement has finished, will be offered. In addition, participants
The research question was based on one of the most will answer a questionnaire that includes open questions
principal problems that the PC population suffers from. regarding the professionals involved, the programme and
Patients and GPs require more tools to face the existing their own experience.
high prevalence of overweight and obesity, which leads
to more risk and high costs for society.70 71 Taking this Sample size
into account, we started with an 8-­session uncontrolled The sample size estimation has been based on the main
open-­label pilot study offered to the public in general, comparison, which contemplates the possible differences
with the main aim of adjusting an ME programme to the between the ‘ME +TAU’ and ‘TAU alone’ groups of
PC population. patients. Based on previous research,72 we assume that ‘ME
We recruited 10 patients from the Arrabal PC health +TAU’ would be able to present high effects compared
centre in the city of Zaragoza who were willing to partici- with ‘TAU alone’ on EE at post test. To operationalise
pate (8 women and 2 men, with an age range of between this, we consider a standardised difference between arms
45 and 65 years). After the last session of this early iter- on the referred main outcome of 0.80.72 To detect this
ation, we inquired specifically about the content of the difference between the groups, assuming a common SD, a
programme and the results they could have experienced 5% significance level and a statistical power of 80% using
during these 8 weeks, the appropriateness of the length a 1:1 ratio, we need 25 subjects in each group. However,
of the intervention and about homework management. these numbers correspond to the sample size needed
We did not quantitatively assess the potential changes under individual randomisation, which is the absolute
of this pilot presentation because we were more inter- upper bound for cluster size—clusters are randomised
ested in how they experienced the programme, as well as and thus we need to allow for the correlation between
possible implementation issues. We specifically asked for the EE outcomes of participants from the same cluster.73
the following aspects: ‘How do you feel about the content To determine the minimum number of clusters needed,
and results of the programme?’, ‘Has the programme we used the formula ‘n * ICC’, where n is the sample size
been long enough?’ and ‘Did you follow the weekly home for each arm under individual randomisation and ICC
task?’ The most common responses pointed out that the is the intracluster correlation coefficient that quantifies
content of the programme was helpful and had changed the amount of within-­cluster correlation for the outcome
their level of awareness of unhealthy eating patterns, but of interest, assuming a typical fairly value in CRTs of
also that the programme had too many sessions, and ICC=0.03,74 with a result of approximately one cluster in

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each arm. Because the number of clusters in the trial is
limited by the number of PC settings available to imple-
ment the ME programme, we increased the number of
clusters to one more than the minimum, supposing that
the cluster size would be at most ‘n/1’. Thus, we fixed
the number of clusters per arm to 2 in order to deter-
mine the required cluster size.75 In order to maintain the
same absolute difference and significance level described
above to achieve 80% power with 2 clusters in each arm,
we needed a cluster size of 16 participants. In addition,
by fixing the cluster size at 16 participants in the same
conditions, we obtained the need of 2 clusters per arm,
equating to a total sample size of 64 subjects under the
condition of equal cluster sizes. Finally, we inflated the
numbers to reach a total sample size of 76 patients (38
per arm), considering a drop-­out rate of approximately
20% at 1-­year follow-­up.76 This can be considered an effi-
Figure 1 Restricted randomisation applied to primary care
cient design based on the rule that cluster size should (PC) health centres. Figure represents the matching process:
not exceed the number estimated in each arm under the maximally homogeneous PC health centres pairs in terms
individual randomisation.73 This number also enlarges of the predefined average per capita income of the assigned
the sample size under individual randomisation in a population (higher average per capita income pair and lower
measure that includes the design effect ‘DEFF=1 + (m – average per capita income pair) will be divided randomly
1) * ICC’—where m is the average number of patients per between the ‘mindful eating (ME) + treatment as usual (TAU)’
cluster—with a value of DEFF=1.45, and thus demanding (intervention) and only ‘TAU’ (control) arms. The number of
points reflects the cluster size. C, cluster.
an increase with regard to individual randomisation of
around 45%.57

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taken into account so as not to lose post-­treatment and
Recruitment follow-­up measures.
Participants will be identified and recruited in PC settings
Randomisation, allocation and masking of study groups
by involving the GPs of patients who fulfil the study The identification and inclusion of participants will take
criteria. The GPs will complete referral forms, indicating place before the randomisation of clusters, ensuring
that the patients meet the criteria and will provide a allocation concealment to cluster guardians (who are
brochure and an information sheet to present the study. the corresponding GPs), assessors and patients during
The GPs will send the referrals and the patients’ signed recruitment.77 78 Restricted randomisation will be applied
written consent forms by mail to a local researcher. Some to balance clusters, creating comparable arms in terms
patients may prefer to postpone their decision to partici- of the number of clusters but also in the average per
pate in the study, in which case they will be provided with capita income of the assigned population to each PC
information about how to contact the research team (by health centre.79 The rationale of this is that this variable
phone, email or leaving their information on the group’s has been inversely related to the presence of overweight
website). and obesity,80 81 and also to possible limitations in gaining
An assessor-­researcher, who is not part of the study benefits after mindfulness-­ based programmes.82 The
team, will contact the participants to agree on the estab- maximally homogeneous cluster pairs in the average per
lished evaluation times and will clarify any points, ensure capita income at the level of PC health centres will be
that the participants have read the information about matched and randomly divided between the intervention
the study, and ensure they have understood the two and control arms, as shown in figure 1. As a result of this
experimental conditions. The assessor will then finally matching process, we will obtain a number of strata that
determine their inclusion in the study after considering is half the total number of clusters to be allocated, which
the inclusion and exclusion criteria described above, is considered the minimum number of clusters to safely
and before contacting an independent researcher to achieve balance.83 This matching procedure is partic-
implement the randomisation sequence to the clusters. ularly useful when there are few clusters in the study,84
Recruitment will be performed consecutively until the and it provides face validity regarding balance between
final sample size is reached. The assessor will collect the allocation arms.85 No other cluster or individual-­ level
baseline data, including the primary outcome. GPs will imbalances for important covariates related to the main
adhere to the study protocol before the randomisation of outcome are expected between arms.
clusters, and they will be blinded to the allocation group An independent assistant not involved in the study
of clusters together with the assessor-­researcher. Possible will be in charge of performing the cluster randomi-
migrations of participants out of clusters will be especially sation by using a computer programme to generate an

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unpredictable random allocation sequence. This assistant request, and the funders and involved clinicians will also
will be unaware of the characteristics of the study and will receive an anonymised report.
inform the data manager of a code that corresponds to
the type of treatment to be added to the baseline data. Interventions
The meaning of this code will be unknown by the person All participants, regardless of the treatment arm in which
in charge of randomisation and by the data manager— they have been assigned, will receive the TAU at the PC
it will be known only to the data monitoring committee level. According to the pragmatic nature of the present
(DMC) and will be kept under a password-­protected data- study, ad hoc adherence optimisation procedures will
base system. The DMC will receive the baseline data from not be used, as not to interfere with diverse routine prac-
the data manager and will be in charge of implementing tices. In fact, patients will be free to decide whether they
the random sequence. will discontinue intervention on request. If participants
Participants will agree to their inclusion before finding decide to be part of any other medical or psychological
out the treatment to which they will be allocated. As we treatment focused on changing their relation with the
have previously explained, the baseline assessor will be food or weight reduction, the contact person of the study
blind to the type of treatment that will be administered to should be informed to exclude those participants when
clusters and patients. This assessor will be different from developing the corresponding data analyses. The rest of
the person responsible for collecting the post-­test and the treatments will be allowed.
follow-­up measurements, who will be a blinded external
assistant specifically advised not to ask for the study T​ reatment as usual
aims and the allocation of clusters/patients. GPs will be TAU in PC is any kind of treatment administered by the
blinded to the intervention arm to which each patient GP to the patient with overweight or obesity. According
is allocated since their intervention should be based to nutritional status, overweight or obesity, as well as the
only on usual practice, and they will also be advised not presence of comorbidity, different actions can comprise
to ask for that information. The person responsible for the treatment offered at the PC level. For individuals
performing the data analysis will be blinded to the type of presenting with overweight (BMI 25–29.9 kg/m2) or
obesity (≥30 kg/m2) but with no comorbidities, PC

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intervention in the main outcome analysis, receiving the
database without any data that permits this identification. teams organise care plans adjusted to the characteris-
Any doubt regarding the data will be resolved in contact tics of patients to enable them to achieve a normal BMI
with the data manager, and the other researchers will be range (BMI 18.5–24.9 kg/m2). In cases of suicide risk,
blinded while analysis and data interpretation processes severe social dysfunction or worsening of symptoms, it
is recommended that patients are referred to mental
are taking place. However, due to the characteristics of
health facilities.86 In Spain, GPs spend a minimum of 4
the intervention, participants will be able to know what
years completing their medical specialty. The GPs who
kind of intervention they are receiving; thus, this will be a
will be participating in the present study have more than
single blind study—although both ‘ME +TAU’ and ‘TAU
20 years of clinical experience treating patients with over-
alone’ groups will be treated one way or another. A verifi-
weight or obesity, and they will have undergone specific
cation of successful blinding at all stages referred will be
training focused on endocrinology and internal medicine
performed by the DMC.
for a better understanding of obesity and its implications
and comorbidities such as diabetes and hypertension.
Data management
A researcher psychologist will perform the data handling M
​ indful eating
and monitoring. All study information will be confined The ME group will be composed of 7 weekly group
in secure drawers with limited access. Electronic data sessions with a minimum duration of 2 hours, mixing
files will be password protected. Participant codes and theoretical content with practices. Sessions will always be
personal information will be stored in a separate password-­ the same day of the week, except for bank holidays or
protected file. Data will be stored for 5 years after the end eventualities, and will be conducted by a clinical psychol-
of the study. Only the researchers directly involved in the ogist. This psychologist has been specially trained in ME
study and led by the principal investigator will have access programmes, for example, Mindfulness-­ Based Eating
to the final dataset. Paper-­based data entry will be double Awareness87 and Mindful Eating Conscious Living,88 and
checked, and possible out-­of-­range values will be specifi- he is also a board member of The Center for Mindful
cally revised. In case data are actually correct, they will be Eating (TCME).89 The TCME is a non-­ profit interna-
analysed altogether by boxplot graphical representations tional organisation that provides resources for educating
to see whether the previously described values constitute professionals in the field of ME. This clinical psycholo-
extreme outliers. If extreme outliers appear, a sensitivity gist has also run several ME groups over the past 5 years
analysis after removing them will be performed to ensure and he is a coauthor of the manual on which the present
robustness of results. The study results will be presented programme was based.90 Group sizes will range between
via peer-­review publications and congresses. In addition, 8 and 12 participants in four different subgroups of treat-
the study participants will receive a summarised report on ment. At the end of each session, participants will receive

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Table 3 Summary of the mindful eating sessions and content
Session Content Practices Home task
Session 1 ►► Brief introduction ►► Breathing practice ►► Breathing practice
Mindful eating introduction ►► Importance of the present moment ►► Raisin practice ►► Decreasing the eating rhythm
►► Attention and motivation ►► Minimeditation
Session 2 ►► What to do with your body and your mind ►► Body scan practice ►► Minimeditation
Mindful eating and while meditating ►► Healing self-­touch ►► Body scan
compassion ►► What emotional eating is and how to
distinguish it from physical eating
►► Using compassion to achieve change
Session 3 ►► Body signals ►► Mindful eating practice ►► Breathing practice
Integrating consciousness ►► Hunger and satiety ►► Integrating consciousness ►► Becoming aware of hunger
practice and satiety signals
►► Self-­acceptance

Session 4 ►► How to structure mindfulness practice ►► Compassionate body scan ►► Minimeditation

Satiety and appetite values (formal and informal) ►► Personal value practice ►► Stopping in the middle of
►► Eating psychoeducation ►► Chocolate practice the meal
►► Body scan
Session 5 ►► Compassionate coping ►► Conscious choice ►► Conscious movements
Conscious choice and ►► Knowing when to stop eating ►► Full stomach practice ►► Becoming aware of the
forgiveness ►► Potluck preparing ►► Forgiveness meditation continuous feeling while
eating until satiety
Session 6 ►► My plate ►► Mindful walking practice ►► Emotional eating chain
New balance consciousness ►► Potlucking ►► Emotional self-­regulation ►► Mindful walking
►► Nutrition and emotional eating triggers ►► Potluck practice ►► Becoming aware of our
(chain) feelings and their adjustment
Session 7 ►► Keeping up with the knowledge ►► Breaking the chain –

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Wisdom and pursuing the ►► Facing yourself after relapses ►► Wisdom meditation
path ►► Our inner critical voice

theoretical content and homework activities to be prac- heaviness, this indicates that the food intake was
tised during the week. The programme is summarised in excessive. When the sensation is related to satiety,
table 3 and described as follows: this is a good moment to stop eating. The satiety
►► Session 1: this session is aimed at motivating home signal is identified through mindfulness (chocolate
practice and is complemented by an introduction to practice).
ME. Observation is an attitude that will be developed ►► Session 5: it address the fullness sensation as some-
during this session, allowing patients to connect with
thing different from not being hungry and the ‘EE’
their emotions, thoughts and body sensations, moment
concept. It encourages us to accept all we experiment,
by moment, to be aware of possible unhealthy eating
patterns. The awareness of automatised patterns can managing the inner critical voice. The practice of
give patients the chance to change behaviour, making conscious movements to become aware of the body
decisions more connected with necessities. The ME and bring full attention to the present moment is a
efficacy mechanisms are explained. guide in decision-­making.
►► Session 2: the objective of this session is to be aware, at ►► Session 6: this session emphasises the relationship
any moment, of one’s hunger level, observing eating between the knowledge of feeding and nutrition and
patterns and their possible relation with the emotions conscious and balanced decision-­ making. It works
that are felt at the same time. This session works by with emotional triggers through the chain practice
identifying EE triggers and knowing how compassion and also integrates the potluck practice. Foods that
and the inner critical voice are related to the food. trigger greater EE are shared and discussed in the
►► Session 3: the objective is to recognise the differences
group.
between real hunger signals and other body sensa-
►► Session 7: this session is focused on binge episodes
tions generated by the environment that trigger the
and how we can manage EE in the future by substi-
desire to eat. Training at the body consciousness level
helps one find the point of balance that allows for tuting the inner critical voice with a compassionate
eating and enjoying, paying attention to eating, feel- voice. The way we are aware of our thoughts, emotions
ings, body sensations, emotions and thoughts. and decisions is what allows us to break the chain of
►► Session 4: This session aims to work with the EE and start a new relationship with food, managing
corporal sensations that food produces. When the and making decisions about emotions and food in a
physical sensations are of discomfort, swelling or wiser way.

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Outcomes understanding of one’s experiences as part of shared
Patients will be assessed at baseline, after treatment and reality that all people go through during personally
at 1-­
year follow-­ up to test whether the improvements challenging or difficult times.108 It has been observed
achieved during therapy are maintained in the long term. that receiving a self-­ compassionate induction to cope
Several variables will be assessed to compare the ‘ME after the experience of breaking the diet enables further
+TAU’ and ‘TAU alone’ groups to evaluate the effects of regulation to occur,109 and that self-­compassion could
the ME programme. EE styles, which will compose the be a determinant for weight regulation and losing
main outcome, have a direct relation with overweight weight.110 111 Overall, the combination between mindful-
and obesity.51 These eating styles are related to how much ness and self-­compassion appears to be complementary,
you eat and even more to how you eat. The Dutch Eating creating better health-­related outcomes for both eating
Behaviour Questionnaire (DEBQ) is a good evaluator behaviours and obesity.55 All the study measurements,
of this construct (EE is a subscale of this questionnaire) together with the sociodemographic data taken at base-
and has been rated ‘up to the mark’, that is, appropriate, line, are summarised in table 4.
by the Dutch Committee on Test and Testing and by the
European Federation of Psychologists Association.91 ​Sociodemographics
The secondary outcomes will be other eating patterns The following sociodemographic information will be
that could be modified as a result of the application of collected at baseline: age, sex, nationality, marital status
the programme, such as external and restrained eating, (single, married, separated/divorced or widowed), work
also measured by the DEBQ (both are also subscales activity (student, worker, sick leave, unemployment,
of this questionnaire); binge eating, measured by the housewife, disability or retired), study level (no studies,
BITE92; and eating disorder risk, measured by the Eating primary, secondary or university) and the PC health
Attitude Test (EAT).93 Other secondary outcomes will centre of provenance in the city of Zaragoza, Spain (Las
be emotional states, which affect the way we eat. To eval- Fuentes Norte, Parque Goya, La Almozara or La Jota).
uate this, the General Anxiety Disorder (GAD-7), which
is one of the most frequent screening scales in PC, will ​Main outcome
be used to assess anxiety.94 The GAD-7 is often used in The DEBQ was designed to measure eating styles that

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combination with the Patient Health Questionnaire may attenuate or contribute to the development of
(PHQ-9) to measure depressive symptoms, which will overweight and obesity.112 It comprises three scales that
also be included.95–100 Physiological variables will also be measure emotional, external and restrained eating.
important to evaluate whether changes in eating style and The EE pattern corresponds to the tendency towards
emotional state have consequences for the general health overeating in response to negative emotions113 and will
condition in the long term. For this purpose, anthropo- be considered the main outcome of this study (both
metric and vital signs will be assessed—including weight, external and restrained subscales will be included as
abdominal diameter, diastolic blood pressure (DBP) and secondary outcomes even though they are presented
systolic blood pressure (SBP)—as well as blood tests, all of here). Emotional and external eating are correlated with
which are described next. BMI. The restraint factor has shown relationships with
To relate the awareness of the present moment and the other scales, such as the EAT-26 and the Restrain Scale,
way in which compassionate and critical attitudes towards which measure eating disorders and restrained eating,
the self can be managed as possible emotion regulation respectively. The Spanish version112 of the DEBQ114 has
strategies,56 101 the evaluation of the dispositional mind- 33 items, 13 of which refer to the EE scale (eg, ‘Desire to
fulness and self-­ compassion levels will be pursued as eat when irritated’) and 10 of which refer to the external
mechanistic variables of the programme through appli- (eg, ‘Eating when you feel lonely’) and restrictive (eg,
cation of the widely used Five Facet Mindfulness Ques- ‘Difficult to resist delicious food’) scales. The items can
tionnaire (FFMQ), the Mindful Eating Scale (MES) and be rated on a five-­point Likert-­type scale, with a score
the Self-­Compassion Scale (SCS). Mindfulness is a way of 1 indicating ‘never’ and 5 indicating ‘very often’. In
of self-­
regulating attention to focus it on the present a non-­ clinical sample of normal weight, overweight,
moment experience with an attitude of curiosity, open- and obese participants, Cronbach’s alpha coefficients
ness and acceptance of bodily sensations, thoughts and presented values between 0.96 and 0.97 for the DEBQ-­EE
emotions.102 Deficits in dispositional mindfulness have subscale, between 0.79 and 0.84 for the DEBQ-­external
been reported in patients suffering from eating disor- eating subscale and between 0.92 and 0.94 for the DEBQ-­
ders and obesity.103 104 It has also been observed that the restrained eating subscale.33
non-­judgemental awareness of physical and emotional
sensations, specifically associated with eating, correlates ​Secondary outcomes
inversely with the severity of eating disorders105 and We will administer the BITE92 in its Spanish version.115
increases healthy food choices.106 Finally, self-­compassion This questionnaire is used to measure the presence of
has received much attention in assisting individuals with bulimic symptoms in non-­clinical samples and has two
eating behaviours and weight regulation.107 It is a kind subscales measuring symptoms (eg, ‘Desire to eat when
approach towards oneself, with a mindful awareness and irritated’; with 30 items in a ‘yes’/‘no’ dichotomous scale;

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Table 4 Study outcomes
Variables Assessment area Level of measurement Time to assessment
Sociodemographic Age, sex, nationality, marital status, work activity, Varies depending on the Baseline
study level and PC health centre distribution of data
DEBQ Eating style: emotional, external and restrained Treated as interval Baseline, post treatment and
eating 1-­year follow-­up
BITE Binge eating: symptoms, severity and frequency of Treated as interval Baseline, post treatment and
bingeing 1-­year follow-­up
EAT Eating disorder: dieting, bulimia and food Treated as interval Baseline, post treatment and
preoccupation, and oral control 1-­year follow-­up
GAD-7 General anxiety symptoms Treated as interval Baseline and 1-­year follow-­up
PHQ-9 Depression symptomatology Treated as interval Baseline and 1-­year follow-­up
FFMQ Mindfulness: observing, describing, acting with Treated as interval Baseline, post treatment and
awareness, non-­judging and non-­reactivity 1-­year follow-­up
MES Mindful eating: acceptance, awareness, non-­ Treated as interval Baseline, post treatment and
reactivity, acting with awareness, routine and 1-­year follow-­up
unstructured eating
SCS Self-­compassion: self-­kindness, self-­judgement, Treated as interval Baseline, post treatment and
common humanity, isolation, mindfulness, and 1-­year follow-­up
overidentification
Anthropometrics Weight, height, waist circumference and abdominal Treated as ratio Baseline and 1-­year follow-­up
diameter
Blood test Cholesterol total, LDL, HDL, triglycerides, ALT, Treated as ratio Baseline and 1-­year follow-­up
glucose and glycated haemoglobin
Vital signs Systolic and diastolic blood pressure Treated as ratio Baseline and 1-­year follow-­up

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Attendance Compliance with the programme Treated as interval Post treatment

ALT, alanine aminotransferase; BITE, Bulimic Investigatory Test Edinburgh;DEBQ, Dutch Eating Behaviour Questionnaire; EAT, Eating
Attitude Test; FFMQ, Five Facet Mindfulness Questionnaire; GAD-7, General Anxiety Disorder; MES, Mindful Eating Scale;PC, primary
care; PHQ-9, Patient Health Questionnaire; SCS, Self-­Compassion Scale.

range=0‒30) and severity (eg, ‘Do you do any of the the patient should seek professional advice. The EAT-26
following to help you lose weight?’; with 6-­dimensional has an elevated reliability (α=0.80).
items addressing bulimic behaviours; range=0‒39), with The GAD-7 is one of the most frequently used diag-
a total of 33 items. In addition to normative values for nostic self-­report scales for screening, diagnosis and
total and subscale scores in clinical and nonclinical anxiety disorder severity assessment,119 defined as an
samples,116 another measure has been derived to report excessive anxiety and worry (apprehensive expectation)
the frequency of bingeing (item no. 27, ‘If you do binge, related to a number of events or activities associated with
how often is this?’; this item will be mainly framed in experiencing difficulties to control that worry.120 Items
the last month so as not to overlap pretest and post-­test (eg, ‘Not being able to stop or control worrying’) are
measures, with the following type of response: ‘2–3 times rated on a 4-­point Likert-­type scale (between 0 = ‘not
a day’=6; ‘Once a day’=5; ‘2–3 times a week’=4; ‘once a at all’ and 3 = ‘nearly every day’). The GAD-7 inquires
week’=3; ‘once a month’=2; ‘almost never’=1). The BITE about events occurring over the last 2 weeks to know
has shown an internal consistency value of α=0.96 for the how often the patient has been bothered by them, and
symptoms and of α=0.62 for the severity subscales.117 it has shown a sensitivity of 89% and a specificity of 82%
To assess any other eating disorder, we will use the when discriminating patients suffering from generalised
EAT-26,93 in its Spanish version.118 This questionnaire anxiety disorder. The Spanish version of the GAD-7 has
has the following three subscales: dieting (eg, ‘Am terri- shown appropriate psychometric characteristics.121
fied about being overweight’), bulimia and food preoc- We will use the PHQ-9122 to assess depressive symp-
cupation (eg, ‘Find myself preoccupied with food’) and tomatology. This scale is one of the most widely used
oral control (eg, ‘Avoid eating when I am hungry’). The questionnaires to assess the intensity of depression in
EAT-26 is an abbreviated version of the original EAT-40, pharmacological and psychological studies.123 124 It is
with an excellent correlation between them (r=0.98). In useful to monitor the changes experienced by patients
the EAT-26, each item is answered on a 6-­point Likert-­type over time and presents a sensitivity value of 88% and a
scale (‘always’=3, ‘usually’=2, ‘often’=1, ‘sometimes’=0 specificity of 88% to detect major depression. Through
‘rarely’=0 and ‘never’=0), and if the score is 20 or higher, items such as ‘Little interest or pleasure in doing things’

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and using a Likert-­type scale between 0 (‘not at all’) and negatively formulated items, a total score can be calcu-
3 (‘nearly every day’), the PHQ-9 reflects the experience lated, which may range from 24 to 120, with higher scores
of participants during the last 2 weeks. The Spanish vali- indicating greater self-­compassion.129 The SCS total has
dated version, which has shown adequate psychometrics, shown good internal reliability (Cronbach’s α=0.92), as
will be used.86 did the six subscales (ranging from α=0.75 to α=0.81.129
The Spanish validated version of the SCS has demon-
​Process measures strated good psychometric properties.130
The FFMQ-­short form125 is a 24-­item questionnaire that
measures 5 aspects of trait mindfulness, and there is ​Physical parameters
a Spanish version based on it with appropriate psycho- Weight and body measurements will be quantified, with
metrics.126 The five facets of the FFMQ are observing weight in kilograms, and height, waist circumference
(eg, ‘I pay attention to physical experiences, such as the and abdominal perimeter in centimetres (cm); weight
wind in my hair or sun on my face’; four items, α=0.65), without any anthropometric measures is not an accu-
describing (eg, ‘I am good at finding words to describe rate assessment of the physical changes associated with
my feelings’; five items, α=0.79), acting with awareness a healthy food relation. The evaluations will be made the
(eg, ‘It seems I am running on automatic without much same day and just before the psychometric assessments,
awareness of what I am doing’—item reversed; five items, using a measuring tape and the same digital scales.
α=0.80), non-­judging towards inner experience (eg, ‘I Blood tests will evaluate the levels of total cholesterol
make judgements about whether my thoughts are good (HDL and LDL), triglycerides, alanine aminotransferase,
or bad’—item reversed; five items, α=0.73) and non-­ glucose and glycated haemoglobin. The blood test will be
reacting of inner experience (eg, ‘When I have distressing performed in the morning (between 08:00 and 09:00, and
thoughts or images, I do not let myself get carried away all participants should have fasted for 8 hours prior to the
by them’; five items, α=0.68). The participants indicate, test. Vital signs such as DBP and SBP will also be assessed.
on a 5-­point Likert-­type scale, the degree to which each To evaluate vital signs, we will use a vascular screening
item is generally true for them, ranging from 1 (‘never or system (version VaSera VS-1500).
very rarely true’) to 5 (‘very often or always true’). Higher

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scores indicate greater levels of mindfulness. ​Other measures
It has been observed that mindful awareness towards In addition, the number of ME programme group
eating may minimise automatic and impulsive reactions, sessions attended, as well as the number of visits to the
thereby fostering self-­regulation.127 We will measure ME corresponding GP in both groups, will be recorded. Video
through the MES questionnaire.128 The MES question- recordings will not be taken in order not to interfere with
naire has 28 items, including the following 6 factors: the natural way in which exercises are held.
acceptance (α=0.89; assessed through items such as ‘I
criticize myself for the way I eat’), awareness (α=0.82; Harms
for example, ‘It is easy for me to concentrate on what I Thus far, there is no described evidence in the literature
am eating’), non-­reactivity (α=0.77; for example, ‘I can regarding any side effect as a result of specific ME prac-
tolerate being hungry for a while’), acting with awareness tice, although participation in meditation programmes
(α=0.81; for example, ‘I eat something without really in general might exacerbate negative experiences to
being aware of it’), routine (α=0.75; for example, ‘I have a the same extent as psychotherapy.131 Any adverse event
routine for what I eat’) and unstructured eating (α=0.60; observed by the GPs or psychologist in charge of the
for example, ‘I multi-­task while eating’. Items can be rated groups or referred from patients during the sessions or
on a 4-­point Likert-­type scale, with 1 indicating ‘never’ along the whole programme will be communicated to the
and 4 indicating ‘very often’. The MES Spanish validated trial manager (the leader of the research group, who is a
version has shown adequate psychometric features.128 psychiatrist and will be able to refer the patient directly to
The SCS129 is the most used self-­report instrument to mental health services should this be necessary), and also
measure self-­compassion. It is divided into six subscales: to an independent GP and an independent psychologist
self-­kindness (eg, ‘I am kind to myself when I am expe- with broad experience in the clinical field of mindfulness
riencing suffering’); self-­ judgement (eg, ‘When I see and eating disorders; they will act together to form the
aspects of myself that I do not like, I get down on myself’); DMC. If the unintended effects are related to the treat-
common humanity (eg, ‘I try to see my failings as part ment, the DMC will be committed to informing the corre-
of the human condition’); isolation (eg, ‘When I fail at sponding PC physician and providing the individualised
something that is important to me, I tend to feel alone in treatment to each case scenario in PC settings or derived
my failure’); mindfulness (eg, ‘When something upsets to mental health services by their PC physician or the
me, I try to keep my emotions in balance’); and overiden- trial manager if required. Then, the DMC and the corre-
tification (eg, ‘When something upsets me, I get carried sponding PC physician will decide whether to discon-
away with my feelings’). The items can be rated on a five-­ tinue or modify the allocated intervention depending on
point Likert-­type scale, with 1 indicating ‘almost never’ the nature and severity of the side effects. The DMC will
and 5f indicating ‘almost always’. After reversing the audit trial conduct at least three times throughout the

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study (after baseline, post treatment and follow-­up assess- (females present higher EE), weight status (the more the
ments, as well as at the request of any of the members of EE the higher the weight status) and emotional disorders
the research group), in coordination with the psycholo- derived from anxiety and depression (higher levels of
gist responsible for data handling and the psychologist anxiety and depression are associated with greater levels
in charge of the groups—but independently of the other of EE),50 141 142 and thus these variables will be included
parts. To ensure that the procedures are being correctly in the adjusted models.143 The effectiveness of the ‘ME
implemented and that the trial works adequately, audits +TAU’ compared with the ‘TAU alone’ group with regard
will revise aspects such as the level of attendance in group to the secondary outcomes, process variables and physical
sessions and TAU, adverse events emerged through the parameters will be calculated following the same analyt-
study and possible extreme cases that might require ical strategy used for the main unadjusted analysis. In
specific attention in any of the variables assessed. addition, secondary outcomes will be also analysed using
adjusted models controlling for sex, weight status, anxiety
Analysis strategy and depression. ESs of all the adjusted models will be esti-
The reporting of the results will follow the Consolidated mated from adjusted average marginal effects (AMEs),
Standards of Reporting Trials recommendations.132 133 using the actual observed values for the variables whose
Sociodemographic and clinical data will be described at values are not otherwise fixed.144
baseline by means of frequencies and percentages, for Further exploratory analyses of the EE primary outcome
categorical variables, or by means and SDs, for contin- will be developed to estimate the complier average causal
uous variables. Treatment conditions will be compared effect of treatment (CACE) in order to assess the poten-
at baseline by visual inspection to ensure the success of tially unbiased effect of fully participating.145 Compliers
randomisation, as recommended.134 will be only observed among those randomised to receive
the ME programme (ie, individuals assigned to the
​Main analysis control group will not have access to the ME treatment),
The effectiveness of ‘ME +TAU’ compared with ‘TAU and will be defined as those patients who attend at least
alone’ will be estimated at post test, based on the EE main ≥50% of the ME sessions.146 A new variable will be created
outcome, which will be considered a continuous variable to identify whether each patient randomised to the ME

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at the individual level. Multilevel mixed-­effect regression group finally complied or not. Both within-­cluster and
models—including time as an independent variable and between-­cluster baseline covariates of compliers and non-­
subjects and PC health centre (cluster) as random-­effect compliers (intervention group) will be compared, and
variables—will be developed by means of a repeated-­ the CACE estimation will be calculated using the robust
measures (RM) design on an intention-­ to-­
treat basis, maximum likelihood expectation-­ maximisation algo-
using the restricted maximum likelihood method. This rithm for a multilevel mixture model, considering both
method is considered robust in the case of small and/or clustering and non-­compliance.147
unbalanced sample sizes.135 Non-­standardised and unad- The clinical significance of improvements between
justed slopes as well as 95% CI will be calculated. To study groups will be explored by calculating the absolute risk
the specific trajectories of each group throughout the trial reduction and the number needed to treat (and their
and determine whether the differences between groups 95% CI). We will use two criteria for improvement: (1)
are consistent over time, the ‘group × time’ interaction changing to a less severe cluster in the EE main outcome148
will be calculated as a supportive analysis (ie, the 1-­year compared with the one the patient was allocated to at
follow-­up time point will be considered as a secondary baseline, and (2) calculating the clinical significance of
analysis). Cohen’s d effect sizes (ESs) from raw scores improvements by establishing both the cut-­off point and
will be estimated at each time point using the combined reliable change index on the EE main outcome using the
SD at baseline.136 ESs are considered small when d≤0.2; Jacobson and Truax method.149
medium when d=0.5 and large when d≥0.8.137
L​ evel of significance
​Secondary analyses An alpha level of 0.05 will be established using a two-­tailed
A recent study observed that multiple imputation is not test. The probability value relative to the sole primary
necessary before computing RM mixed effects model anal- model, as well as the probability values of secondary anal-
ysis irrespective of the type of missing data,138 and other yses proposed, will not be adjusted on the basis of number
studies have suggested there are no gains in imputing of tests done, although they will be interpreted with due
outcomes in randomised trials.139 140 Thus, imputed caution. No interim analyses will be carried out.
scores will not be calculated to estimate sensibility analyses
regarding any statistics. Nevertheless, supportive analysis
of the EE main outcome at 1-­year follow-­up, as well as Discussion
models of EE at post test and at follow-­up with the interac- The present study proposes the evaluation of a leading
tion of sex, weight status and the baseline levels of anxiety and novel intervention based on ME in the field of
and depression as possible covariates, will be considered. overweight and obesity in the context of Spanish PC
Relationships have been observed between EE and sex settings. The main interest of this study is to evaluate the

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effectiveness of this treatment in changing the relation- I error increases, even using analyses that are prepared
ship with food in patients suffering from overweight or to account for clustering. Thus, we will have to be aware
obesity. The study addresses overweight and obesity from of whether observed standard errors tend to exaggerate
the point of view of the change in intake styles, specifi- the significance of results.147 Nevertheless, because we
cally one of these, the emotional style of eating, which will model non-­compliance and clustering in the CACE
in turn has been linked to overweight and obesity condi- analysis, we will be able to reduce variance inflation due
tions.50 51 53 This study may be able to generate knowledge to the interaction between the two.
to expand the content included in the clinical guide- On the other hand, the measurement of different types
lines for the treatment of these conditions in Spanish PC of outcomes, using self-­report instruments and anthro-
settings and throughout the healthcare system. To date, pometric and vital signs measures, as well as blood tests,
the implementation of these clinical guidelines has been will be a strength of the present study, thus overcoming
shown to be improvable.150 There is a lack of knowledge possible response biases. Furthermore, the exclusion
in this particular field due to the novelty of mindfulness criteria established, although may favour group func-
and self-­compassion interventions in PC settings. One of tioning and patient safety, might also limit the range of
the most important goals here is to generate processes to potential affective symptoms and EE, which is likely to
facilitate new effective programmes to control the high have implications for results. Finally, the fact that the
prevalence of overweight and obesity in PC. Mindfulness-­ instructor-­led ME intervention is conducted in a group
based programmes seem to present certain effectiveness setting creates a particular context that could poten-
for treating obesity‐related eating behaviours, such as EE, tially introduce significant biases related to attention and
external eating and binge eating, with also possible bene- support that are not present in the same way in other
ficial effects in weight reduction,151–153 as well as depres- forms of treatment delivery, such as individual face-­to-­
sive symptoms154 and well-­being.155 face treatments or online psychotherapies.
No particular difficulties are expected regarding the
recruitment of PC health centres and patients with over- Ethical aspects
weight/obesity or their participation and monitoring Written informed consent will be obtained from the
throughout the study.156–158 CRTs involve randomisation participants before they are aware of the group to which

Protected by copyright.
of groups of individuals to intervention or control groups, they are allocated. Patients will be informed with a
and their use is growing because they fit well with the func- detailed overview of the aims and characteristics of the
tioning of healthcare systems when introducing new forms study and the intervention arms, and also that all partici-
of treatment. However, CRTs are particularly limited owing pants will be free to withdraw from the study at any time,
to the loss of follow-­up from individuals and even more before they provide their consent. As mentioned above,
importantly from entire clusters when using restricted patients in the TAU arm will be allowed to partake in the
randomisation methods such as matching, which could psychological intervention programme at the end of the
suppose a break in the pairs of randomised clusters. To avoid study for ethical reasons—they will be informed of this
this limitation, possible missing data will be minimised by a possibility after the 1-­year follow-­up measure to avoid the
careful trial management of the PC professionals involved intrusion of possible expectations that might affect the
as cluster guardians and by attempting to follow-­up all study development of the programme, level of participation or
participants.77 139 The long follow-­up period could turn out outcomes.
to be an added difficulty when trying to evaluate all the The study has been developed according to national
participants at 1 year after the intervention—no outcome and international standards, for example, Declaration
data will be collected for participants who do not complete of Helsinki, Tokyo Convention and the corresponding
follow-­up. Nevertheless, with the assistance of the cluster later amendments. The data will be treated anonymously
guardians, efforts will be made to maintain low drop-­out and will only be used for purposes related to the study.
rates—ideally in the range of 20%—to reduce this possible The limits to fully guarantee confidentiality and privacy
limitation. We will also be cautious regarding ‘breaking the of the participants included in the study will rely on Fair
matching’ when determining the possible impact of base- Information Practice Principles (FIPPS)160—that is, open-
line covariates on the intervention effect, because it might ness and transparency, purpose specification, collection
increase type I error.159 limitation and data minimisation, use limitation, indi-
Possible subsequent difficulties might be those derived vidual participation and control, data quality and integ-
from the fact that the sample size has been estimated rity, security safeguards and controls, accountability and
based on foreign studies,72 because there have previously oversight—and will be in accordance with the ethical
been no similar publications in the Spanish context. standards laid out in the EU General Data Protection
Another limitation is that the intervention will be located Regulation regime as well as the Spanish Organic Law
only in the city of Zaragoza (located in the north-­east on Protection of Personal Data and Guarantee of Digital
of Spain), without having the possibility to expand the Rights, ensuring that the responsibility for protecting data
study area. In this respect, the low number of PC health privacy rests primarily on the data holders. If the necessity
centres playing the role of clusters is likely to underesti- of fulfilling the objectives of the CRT creates a scenario
mate standard errors, something that might lead to type that could lead to a break in the total compliance with

Morillo Sarto H, et al. BMJ Open 2019;9:e031327. doi:10.1136/bmjopen-2019-031327 13

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