Excuse me but medications often needed for reasons involved in individual genetic make can stimulate appetite. It may be a secondary side effect but it is major.
There is no one factor.
My own problem was overeating and straying from a healthier diet. Exercise was also a problem. I used to over do it and get an unmanageable urge to eat.
Insisting on exercise to lose weight is false. We do not burn that much energy with exercise most of us. Some can exercise and manage their hunger around activity. Others are better off managing their caloric intake without exercise as I did for most of a year. The following year I went into the gym to lift weights and rebuild the muscle.
We can point to economics as a factor. Poorer workers make worse food choices. A matter perhaps perceptually of individual value in society. The bulk of the rise in obesity is among the lower middle class workers. It is not exclusive to them. With 60% of workers making under $40k per year many face a harsher reality.



