[stevebmark]

Saying that people gain weight because they consume more energy than they expend is both obvious and too blunt to be useful for weight loss. The same caloric intake of protein, carbohydrates, fat, fiber, preservates, sand, poison, all act differently in your body. You can lose weight in a caloric surplus diet and gain weight in a caloric deficit diet. One fun paradox is some people who train for marathons gain body fat.

I don't have the answer. Ketosis is an example of a weight loss diet where you don't have to count calories, since the body switches into fat burning / fat cell releasing mode by default. Veganism, which starves the body of fat required for normal operation (hormones, celular function), depletes fat stores to use for these functions, and also causes weight loss without having to count calories.

One of the most important things is probably to focus on eating whole foods over processed foods. I'd also consider that fat is more satiating than carbohydrates and protein. One overfeeding study wasn't successful because they couldn't get the fat-eating group to over eat, their bodies stopped them. I'd also consider the glycemic index of foods, since insulin is the signaler to the endothelium receptor to pull excess glucose from the blood into the cells to store as fat.

[jawarner]

It's true that your body doesn't digest all the available calories in food, and the energy extracted from the food is going to vary by food source, along with the digestion profile, or glycemic index.

So, it is true that:

> You can lose weight in a caloric surplus diet

But I don't see how it's possible to:

> gain weight in a caloric deficit diet

There are many sources of digestible and energetic food, even outside the primary 3 macronutrients. There's alcohol, for instances, in addition to the basic fats, proteins, and carbohydrates. Sand I don't understand to be calorically rich at all. Quartz isn't even an organic compound.