Even though the effects of overweight and obesity on diabetes, cardiovascular disease, allcause mortality, and other health outcomes are widely known, there is less awareness that overweight, obesity, and weight gain are associated with an increased risk of certain cancers. A recent review of more than 1000 studies concluded that sufficient evidence existed to link weight gain, overweight, and obesity with 13 cancers, including adenocarcinoma of the esophagus; cancers of the gastric cardia, colon and rectum, liver, gallbladder, pancreas, corpus uteri, ovary, kidney, and thyroid; postmenopausal female breast cancer; meningioma; and multiple myeloma. 1 An 18-year follow-up of almost 93 000 women in the Nurses' Health Study revealed a dose-response association of weight gain and obesity with several cancers. 2 The prevalence of obesity in the United States has been increasing for almost 50 years. Currently, more than two-thirds of adults and almost one-third of children and adolescents are overweight or obese. Youths who are obese are more likely to be obese as adults, compounding their risk for health consequences such as cardiovascular disease, diabetes, and cancer. Trends in many of the health consequences of overweight and obesity (such as type 2 diabetes and coronary heart disease) also are increasing, coinciding with prior trends in rates of obesity. Furthermore, the sequelae of these diseases are related to the severity of obesity in a dose-response fashion. 2 It is therefore not surprising that obesity accounts for a significant portion of health care costs.