Food energy requirements in humans.

The general principles behind the estimation of energy requirements in humans are discussed and a framework is proposed for estimation of energy allowances appropriate to the population of the United States. Although median weights are used for those less than 18 y, lowest mortality values, which approximate the 25th percentile weights for height in the US population, are used as the desirable weights for adults in assessing daily energy needs. For adults the procedure for estimating daily energy allowances involves calculation of resting energy expenditure by use of the Harris-Benedict equation, which is then multiplied by appropriate factors for activity. A factorial approach is followed for the additional needs of pregnancy and lactation. For young children allowances are based on intake data. Tabular data are presented for energy allowances at all ages together with worked examples for a more individualized approach when body size and activity patterns differ significantly from the mean.