Obesity, defined clinically by a body mass index (BMI) ≥ 30 kg/m2, is a serious public health problem that occurs in over 1/3 of American adults [1, 2] and is associated with numerous medical conditions including cardiovascular disease [3], type II diabetes [4], and cancer [5]. Although nutritional intake and physical activity are known to affect relative body weight, twin and family studies have consistently shown a significant genetic contribution to body composition with heritability estimates of 40 to 70% [6].
