Having struggled as a teen with people calling me anorexic it was mainly by obese women or those close to it. They tended to middle class busy bodies who were unable to say no to a cream cake. These obese women were not mentally ill, just lazy, greedy and lacked self control.
I never had a weight problem until I met my now DH. I was always 'normal' weight (according to BMI charts). DH makes food that is very high in fat and would plate huge portions. I ate it all up for around 6 months. One day my trousers wouldn't do up. I weighed myself and found I had gained 40lbs. I quickly made changes to lose the weight. DH has never changed his diet and is now more than 250lbs. He lacks self control, is lazy about exercise, greedy when it comes to potion size and deludes himself when it comes to making choices. He is obese and it isn't a mental illness.
After having DD I still have some weight to lose. Yes I am watching my diet like a hawk and calorie counting to ensure I don't get any bigger.