The thrifty genotype hypothesis, proposed by James Neel in 1962, suggests that some individuals may be genetically predisposed to store and conserve energy more efficiently. Throughout human history, periods of food scarcity and famine may have created a survival advantage for individuals able to store energy effectively when food was available. These so-called ‘thrifty genes’ may have been passed down through generations. However, in the modern environment, where food is readily available and often energy-dense and levels of physical activity are lower, these energy-conserving characteristics may contribute to an increased risk of weight gain, insulin resistance and type 2 diabetes.