Thrifty phenotype refers to the correlation between low birth weight of neonates and the increased risk of developing metabolic syndromes later in life, including type 2 diabetes and cardiovascular diseases. Although early life undernutrition is thought to be the key driving factor to the hypothesis, other environmental factors have been explored for their role in susceptibility, such as physical inactivity. Genes may also play a role in susceptibility of these diseases, as they may make individuals predisposed to factors that lead to increased disease risk. Historical overview The term Thrifty Phenotype was first coined by Charles Nicholas Hales and David Barker in a study published in 1992. In their study, the authors reviewed the literature up to and addressed five central questions regarding role of different factors in type 2 diabetes on which they based their hypothesis. These questions included the following: The role of beta cell deficiency in type 2 diabetes. The extent to which beta cell deficiency contributes to insulin intolerance. The role of major nutritional elements in fetal growth. The role of abnormal amino acid supply in growth limited neonates. The role of malnutrition in irreversibly defective beta cell growth. From the review of the existing literature, they posited that poor nutritional status in fetal and early neonatal stages could hamper the development and proper functioning of the pancreatic beta cells by impacting structural features of islet anatomy, which could consequently make the individual more susceptible to the development of type 2 diabetes in later life. However, they did not exclude other causal factors such as obesity, ageing and physical inactivity as determining factors of type 2 diabetes. In a later study, Barker et al. analyzed living patient data from Hertfordshire, UK and found that men in their sixties having low birthweight (2.95 kg or less) were 10 times more likely to develop syndrome X (type 2 diabetes, hypertension and hyperlipidemia) than men of the same age whose birthweight was 4.31 kg or more. This statistical correlation was independent of the gestation period and other possible confounding factors such as current social class or social class at birth, smoking, and consumption of alcohol. Furthermore, they argued that they were likely to underestimate this association, since they could only sample the surviving patients, and patients having more severe manifestations of syndrome X were less likely to survive to that age. In 1994, Phillips’ et al. found statistically significant