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.
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.