Triggers

Perhaps the Eating Disorders forum might have what you are looking for? https://www.mumsnet.com/Talk/eating_disorders

It’s a weight loss forum, there will be lots of weight loss chat here. If that’s a trigger for you don’t read it.
I find the ttc forum difficult to read so I keep away rather than torture myself.

Tell Mumsnet admin you want a weight gain subforum and they will do it or at least test out if people would use it.

We don't do endless trigger warnings or safe spaces here. It is robust discussion for grownups. If a thread is not for you. Close it and open another.

The exception being if a thread is very extreme in content, in which case report to Mumsnet, who might review, close, edit title if they deem it necessary.

HTH