There are two explanations for it, which are "thrifty phenotype hypothesis
" and "fetal insulin hypothesis.
Thrifty Phenotype Hypothesis. The "thrifty phenotype" hypothesis, put forth by Hales and Barker, proposes that poor fetal and early postnatal nutrition imposes mechanisms of nutritional thrift upon the growing individual.
Interestingly, the thrifty phenotype hypothesis has been challenged by the "fetal salvage" hypothesis which offers a different explanation for the insulin resistance seen in those affected by intrauterine growth restriction .
Type 2 (non-insuli-ndependent) diabetes mellitus: the thrifty phenotype hypothesis
. Diabetologia 1992; 35: 595-601.
This proposal grew out of the Barker hypothesis which evolved into the Thrifty Phenotype hypothesis
. Its relevance to the Indian population with its greater insulin resistance and predisposition to diabetes has been discussed (24).
Type 2 (non-insulin dependent) diabetes mellitus: the thrifty phenotype hypothesis
. Diabetologia 35, 595-601
But in broad outline, the thrifty phenotype hypothesis
holds that in periods of nutritional deprivation, the fetus adopts two strategies to ensure survival: It preferentially shunts blood to the brain from key bodily organs; and during a critical window of intrauterine development it engages in programming of organ structure and function so as to maintain long-term metabolic thriftiness later in life under conditions of poor postnatal nutrition.