Perhaps then we are researching the wrong thing? Why is it that some people are able to subconsciously regulate their food intake just enough to stay healthy wh

Perhaps then we are researching the wrong thing? Why is it that some people are able to subconsciously regulate their food intake just enough to stay healthy while others regularly eat (or drink) 100-200 calories a day more - which, over a number of weeks and months is enough to gain a decent amount of weight.