ABSTRACT
If the intake of metabolic fuels is lower than is required for energy expenditure, the body’s reserves of fat, carbohydrate (glycogen) and protein are used to meet energy needs. Especially in lean people, who have relatively small reserves of body fat, there is a relatively large loss of tissue protein when food intake is inadequate. As the deficiency continues, so there is an increasingly serious loss of tissue, until eventually essential tissue proteins are catabolized as metabolic fuels, a process that obviously cannot continue for long.
