[helpfulmandrill]

The evidence would suggest that it is that hard for an majority of the human population, within the current western social context, food environment etc.

I say that as someone who has lost significant weight and kept it off for a number of years. But it was not as simple as "put down the fork". I basically have to calorie count every morsel. If I left it to my own mind or just told myself to "put down the fork" I'd be fat again in no time. My mind fundamentally doesn't seem to know when I have eaten enough food.