Obesity is one of the greatest public health challenges of the 21st century. The World Health Organization (WHO) estimates for 2005 indicate approximately 1.6 billion adults are overweight (body mass index (BMI) > 25 kg/m2), with 400 million being characterized as obese (BMI > 30 kg/m2). By 2015, the WHO projections predict that the populations of overweight and obese adults will increase to 2.3 billion and 700 million respectively. The major determinant of obesity is the energy imbalance between calorie intakes and expenditures, which can be ascribed to a global dietary shift in favor of energy-dense foods particularly rich in fat and carbohydrates, and a global trend towards sedentary behaviors.