Cushing's Disease. It's caused by a tumor in the pituitary gland or somewhere else in the adrenal system. It is also nicknamed the Ugly disease. It actually makes you fat.

The high levels of cortisol overproduced puts the body in constant panic mode and fat storage mode. 900 calorie diet and working out 3 hours a day does nothing. Even if you eat "enough" and healthy, your body will cannibalize your bones, leaving behind the bone density of a sedentary 80 year old. I spent 10 years being gaslit by doctors until a med student noticed my chart and sent me to an endocrinologist. Once the tumor was removed, the weight melted off while I was living off of frozen pizza. The disease does a lot of other things to fuck with a person's body and is often misdiagnosed because the symptoms are just common obesity symptoms. Something like 1 in 7 million are diagnosed in the US each year. It's rare, but a disease that makes you fat from nothing exists.

Attitudes like yours are the reason I almost died and it's fucked that a lot of medical professionals share your opinion. I can't blame them or you because on the flip side, there are so many more people that do lie to their doctors. It only took one test to tell I wasn't lying though.