Review of adaptability of adults and children to short and long-term energy restriction

Adults ideally exist in energy balance whereby energy intake equals energy expenditure. The majority of energy expenditure is attributed to the necessary metabolic functions of body organs and muscle. A smaller but varying proportion is attributed to voluntary physical activity. Children require additional energy for growth. In response to energy restriction, the body will use available energy to preserve the most vital organ functions at the expense of body mass and growth.

This review discusses the concept of adaptation to energy restriction and the time course of varying degrees of energy restriction on body mass and related health consequences. The purpose is to review evidence of the impacts of degree and duration of energy restriction in populations in low-income countries (LIC) to provide guidance towards identifying potential critical energy intakes levels.