A lot of the nutrition researchers continue to argue that the body needs to obey the laws of thermodynamics, that is energy in minus energy out has to equal weight gained or weight lost. Using that definition, the way to lose weight is to create a negative caloric balance (by cutting food or increasing energy expenditure) such that the weight disappears. That viewpoint neglects the fact that the body is not a closed system, and the internal cellular metabolism depends on many aspects, one of which is thought to be the macronutrient composition of the food that goes in. For example, protein is ...