Fat and fertility: demographic implications of differential fat storage.

Anthropologists interested in human nutrition have become intrigued by the possibility of a link between nutritional status, fat stores, and fertility. Frisch (1978) and Frisch and McArthur (1974) have hypothesized such a link, based on studies of body composition at menarche and menstrual dysfunction in anorectics. This review indicates that both over- and undernutrition may interfere with reproductive function, but probably do so only when extreme. Evidence for fat as a regulator of fecundity is conflicting and is best documented for age at puberty. Effects of fat on birth interval (a demographically more significant parameter) are confounded by the influence of lactation. A review of hormonal and metabolic patterns in obesity and inanation indicate similarities between these conditions and general or psychological stress. It is suggested that fat is better seen as an indicator of systemic function than as a single independent factor. The adaptive value of fat for human populations may lie in its ability to enhance work performance as much as in its influence on fecundity.