Read all those conditions associated with obesity that I posted from the NHS site. Do you think those are all mental health conditions?
But they are a result of being morbidly obese. If the person returned to a normal BMI then the risk of developing those conditions would diminish.
If therapy is so successful then why not treat morbidly obese patients with therapy rather than very risky surgical procedures?
Why does anyone need therapy or surgery for something that is neither a mental health condition nor a physical health condition?
I guess they don't. If it isn't seen as either a mental or physical condition then I presume the surgery is more akin to cosmetic surgery. That isn't treating a mental or physical illness but is available.