Calories matter, but some foods have more value. Protein is the one nutrient the body cannot store. So when protein intake is limited, the body takes it from muscles and organs. Fat is important for neurons, and carbohydrates are necessary for energy. When carbohydrates are restricted, then body then breaks down muscle to serve the energy needs, this is inefficient and chronic deprivation leads to generalized weakness.. Few soldiers were obese due to constant exercise and restricted rations. Beer and wine did provide carbohydrates.