I know this is an emotive subject so I'd appreciate if you read what I actually have to say about this before responding.
The body positivity movement has been gaining pace for some time with more and more people building quite profitable businesses out of it and getting a lot of media attention. (E.g one women has an Instagram account with 1 million followers)
I absolutely love its central message that diet culture is harmful and makes you bigger as well as its emphasis on 'you have worth and value whatever size you are.' And for the record I know several bigger women who are absolutely drop-dead gorgeous. You can absolutely be beautiful at any size.
But more and more I think aspects of the movement are incredibly damaging. It's changed from saying 'you matter' to saying 'it's absolutely ok to be extremely overweight. If you are gaining, don't worry. Keep eating.' I see this exact message on social media on a regular basis.
I think this is profoundly anti-woman. We live in a capitalist society where it's fair game to make money just about any old way. Food companies pump their food full of sugar and sweeteners directly knowing that makes people eat it compulsively. Men (generalising but most big companies are headed by men) make an absolute fortune from people getting bigger. As someone who has lost nearly 7 stone in my life I can say that life, at worst, is much harder when you're big, as a general rule. If you are very large and healthy then that is great (really), but you most likely haven't hit 60 yet. Bodies begin to break down very quickly if you are large at that age. I can't begin to say how cross it makes me that companies exploit this when people could be looking forward to a healthy old age. I don't believe being overweight is an individual failing - it is these companies' fault.
I really hate gastric bypass surgery for several reasons but evidence exists that your rate of getting several cancers drops by 87% for losing a significant amount of weight after surgery. 87%! Cancer is grim. It is completely irresponsible to spread the message that getting very big is fine. Instead it should be that whilst you should love yourself first and foremost, loving yourself involves feeding yourself nourishing healthy foods so you can have as lovely and healthy a life as possible. (Eating nourishing healthy food does not equal dieting, to clarify once more). Knee replacements, cancer and diabetes in old age does not make for a lovely life. I am in my 30s but have spent a lot of time in hospital and believe me, there are a million other things to do with one's time that are better/more fulfilling/more pleasurable
If anyone criticises this movement they generally get rounded on and told they have 'faux concern.' It shuts down the debate very successfully. This movement is also heavily pushing the 'some women have penises' line too which is another debate but the whole thing just feels so cultlike.