> the energy expenditure must be higher than the intake I think you might be overestimating the predictive power of this statement. The reason that these fad

> the energy expenditure must be higher than the intake I think you might be overestimating the predictive power of this statement. The reason that these fad diets and questionable research end up being so popular is that people have a huge amount of anecdotal evidence that this does not apply as a necessary condition for weight loss. I think it would be hard to argue that it isn't sufficient; assuming that "energy expenditure" and "intake" are well-defined (note that even the model of "calories" in food is not a chemical notion, as many think, it's a heuristic based on a known incorrect model of metabolism), but people see evidence all around them (once again, anecdotal, and in some cases based on incomplete evidence) that people who neither restrict input nor expand expenditure can maintain a healthy weight. People want there to be a magic bullet that will let their metabolism shift into a state where the body would simply stop storing excess calories as fat. I'm fairly convinced that we haven't yet found it, but I think it is a laudable goal. And, because losing weight has positive health and social implications, this is a place where people are desperate enough for a solution that won't involve unpleasantness that they're willing to believe unreasonable things.