Adult nutrition and growth

We provide microeconomic foundations for the commonly assumed subsistence constraint on consumption and demonstrate that the theory is consistent with several important features of development. In principle, subsistence is consistent with different combinations of food consumption, energy expenditure, body weight, and health. In practice, caloric intake has remained remarkably constant over the course of development, giving the appearance of a minimal subsistence constraint in consumption alone. We argue that the trendless nature of caloric intake results from a positive income effect on food consumption being offset by a reduction in the need for food as the energy requirements of work decrease with development. The theory helps explain the observed patterns in body mass, fertility, and economic growth rates for more than two centuries.