True Fit for Me — Thrifty Gene Hypothesis
Thrifty gene hypothesis - an overview | ScienceDirect Topics
According to the hypothesis, the 'thrifty' would have been advantageous for populations, especially women, because it would allow them to fatten more quickly during times of abundance. Fatter individuals carrying the thrifty genes would thus better survive times of food scarcity. However, in modern societies with a constant abundance of food, this genotype efficiently prepares individuals for a famine that never comes. The result is widespread chronic obesity and related health problems like diabetes.
Thrifty gene hypothesis - OurMed
While James Neel was engaged in the research that would lead him to reject the "thrifty genotype" hypothesis (see below), the notion of "thrifty genes" was catching on with other researchers and public health authorities.