This article provides the reader with steps needed to accurately assess patient nutrition behaviors that contribute to weight gain, inability to lose weight, or inability to sustain weight loss. Evidence-based approaches in nutrition therapy that can create the daily energy deficit needed to produce 1/2 to 2 pounds of weight loss per week, and the strategies to create the energy deficit, are presented. To optimize health, long-term weight loss maintenance is needed. The benefits of using a multidisciplinary team approach in treating obesity are highlighted.