The thrifty phenotype and related developmental hypotheses
The developmental origins of health and disease (DOHAD) hypothesis proposes that impairment of fetal and infant development leads to lasting, perhaps permanent, changes in organ structure, body composition, and metabolism. The critical factor, however, is thought to be dysadaptation, whereby the environmental circumstances in later life do not match those the person is programmed for. This kind of mismatch is particularly likely in migrant populations leaving rural parts of South Asia (where nutrition is sometimes limited) and settling in affluent, nutrition-rich countries. South Asian babies are born small but with relatively well-preserved fat depots, especially on the torso and intra-abdominally. This relative central preservation of fat is a characteristic that remains through life. The thrifty phenotype and related hypotheses attribute it to fetal and early life growth and development. The empirical evidence suggests, however, a modest role for these ideas in explaining disease outcomes in South Asians in adulthood.