The energy deficit theory is based on the first law of thermodynamics (I believe), however they conveniently forgot that a caveat on the law is that it requires a closed system. A human is obviously not a closed system.

It's not an accident that calorie counting as the method of weight loss has failed as the spread of obesity has trampled all over it..although there are myriad other factors of course.

Part of the problem is that it's too short sighted, it's not sustainable in most people, especially alongside exercise and a stressful career...etc. People tend to rebound against it and yo-yo diet, although healthier younger people can get away with it more easily perhaps. You definitely can lose weight with a caloric deficit, but that is not the same thing as whether you should, nor whether need a calorific deficit to lose weight, nor indeed whether it's good for you.

Charles Poliquin (arguably the worlds premier strength coach) has thoroughly disproven it, it's torn to bit's in a book called The Obesity Epidemic (author's name escapes me at the mo), there are quite a few well respected names who think it's specifically what you eat, not overeating itself.

You don't need to restrict your calories if you're not eating grains and other such crap, and lifting...etc, besides on natural food, satiety kicks in. It's one of those things that's ahead of it's time, and everyone will resist it because it's not what's been drummed into us for years.

Don't take my word for it, do your own research if you want and see what you come up with. I did, as well as taking the advice of one or two well placed specialists. I'm persuaded by the logic but have a look for yourself, you can get into all sorts around this to do with hormone regulation and whatnot, it's fascinating stuff.

PS