Healthy aging involves the interaction between genes, the environment, and lifestyle factors, particularly diet and physical activity. Worldwide, the increase in life span has led to an increase in morbidity and mortality as the result of chronic, lifestyle-influenced diseases such as type 2 diabetes, cardiovascular disease, and cancer. Nutrient deficiency diseases are giving way to energy imbalances, and links between diet and chronic disease are becoming clearer. The global demographic, epidemiologic, and nutrition transitions are dramatic and point to an urgent need to focus on preventive approaches in health care. Thus, nutrition research has shifted from focusing exclusively on alleviating nutrient deficiencies to also stressing chronic disease prevention. Ongoing initiatives to optimize long-term health and promote healthy aging are based on the concept of functional fitness, ie, the ability to lead an active and healthy life. The Dietary Reference Intakes provide a framework for assessing nutrient adequacy at the population and individual levels. In addition, the Healthy Eating Index provides a single summary measure of diet quality. To effect changes in lifestyles to optimize health as we age, health care providers need to consider all the lifestyle and environmental factors contributing to suboptimal eating and lifestyle patterns.