Who are you calling fat
This was a really confused programme, firstly it did not establish effectively why these fatties should get together. On the face of it to merely chew the fat. Boom Boom!
The only bit that had worth was where the DNA doctor said "you choose to be fat" but your ability to have strong will and resist temptation can be genetically influenced. His conclusion was broadly that temptation needed to be removed the person would make the then easy choice to be thin, and knowledge was power.
As for the evangelising body positive person, she had the gift of articulacy over one narrow philosophical viewpoint, namely "we should not allow being fat to contain or constrain our ambition and lives" and of course we all agree. However she subverted this line of thought and twisted into a "community of fatness" (no such thing) with a complete disregard to the vulnerable people she had around her. Had I been the Director I would have intervened, she was both a bully and her thoughts were "dangerous" within this vulnerable mental health setting.
The programme was a disaster as it did not arrive at the simple conclusion that the NHS needs to help and support people to lose weight and lead healthy lives by having GP checks for all annually and then run, fat clubs, fitness clubs, Talking therapies, etc etc. I would also add we have temptation everywhere and this needs curtailing unless it's the healthy option.