genes that helped our ancestors survive occasional famines. It has been argued that the thrifty genotype is just part of a wider spectrum of ways in which genes can favor fat accumulation in a given environment. These ways include the desire to overeat; the tendency to be sedentary; a diminished ability to utilize dietary fats as fuel; an enlarged, easily stimulated capacity to store body fat [11, 12]. The variation in how people respond to the same environmental conditions is an additional indication that genes play an important role in the development of obesity [13]. This is also consistent with the notion that obesity results from genetic variation interacting with shifting environmental conditions. Recent advances in genetic epidemiological approaches have identify several genetic loci for obesity. This review will focus on several established loci that influence obesity. Identifying the genetic factors underlying the heritable risk of obesity will contribute to our basic knowledge of the biology of energy balance, and might even highlight molecules and signaling pathways that can be targeted for therapeutic intervention.
