Traditional approaches to treating overweight and obese adults by focusing on individual weight loss have not been effective in stemming the tide of obesity in the population. Recent research has identified critical factors that, as they accumulate and interact over an individual's life span, may put a person at risk for obesity. These factors include rapid weight gain in infancy and childhood, early puberty, and excessive weight gain in pregnancy. Based on this research, a life cycle perspective can be used to develop comprehensive interventions that address the multiple determinants of obesity. Because obesity tracks across generations, it is essential to adopt effective obesity prevention measures now to prevent even higher rates of obesity in future generations. Dietetics professionals can reduce individual risks by providing nutritional services that support appropriate weight gain in childhood and pregnancy. We can also advocate for policies in communities, schools, and worksites that support breastfeeding, ensure access to health-promoting foods, and provide opportunities to be physically active.