Physical activity has been defined as "bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above the basal level." This review operationalized this definition to include interventions promoting aerobic- or strength-related physical activity. We did not review interventions focusing primarily on flexibility or balance. A healthful diet promotes health and reduces risk of chronic disease through nutritious eating patterns. For this review, we considered dietary counseling that promoted a balanced diet (e.g., appropriate energy content); balance of fats (e.g., consumption of mono- and polyunsaturated fats, omega-3 fats, avoidance of excess saturated fat, avoidance of trans fats); increased consumption of fruits and vegetables; increased consumption of legumes; increased consumption of lean proteins; increased consumption of non- or low-fat dairy; diet balanced in carbohydrates (e.g., consumption of whole grain and fiber, avoidance of excess refined carbohydrates, including excess sweetened beverages); and avoidance of excess sodium. We did not review dietary counseling that focused only on micronutrient intake, vitamin and/or antioxidant supplementation, or alcohol moderation. Diseases associated with physical inactivity and poor diet rank among the leading causes of illness and death in the United States, and are well established determinants in many chronic diseases, including cardiovascular and cerebrovascular disease, hypertension, dyslipidemia, and type 2 diabetes. Convincing evidence suggests that regular physical activity decreases CVD risk and numerous studies have shown an inverse relationship between exercise and heart disease mortality. Similarly, regular exercise increases high-density lipoprotein (HDL) cholesterol and decreases triglycerides, blood pressure, and risk of CVD events. Studies have also shown that diet clearly affects cardiovascular health. Diets high in fruits and vegetables can decrease CVD. Evidence also suggests that saturated and trans fatty acids increase CVD while linoleic acid, fish oils, plant sterols and stanols, alpha-linolenic acid, oleic acid, and nuts decrease CVD. Likewise, there is convincing evidence that high sodium intake increases high blood pressure, while potassium can decrease blood pressure. Available evidence strongly suggests that regular physical activity decreases an individual's risk for type 2 diabetes, likely through improving insulin sensitivity and reduced total and abdominal adiposity. Similarly, excess energy intake increases obesity, which may increase the risk for type 2 diabetes. While there is little evidence that total carbohydrate intake is associated with diabetes, high glycemic index of a diet may be a risk factor. Evidence also suggests that saturated fatty acids can increase the risk for type 2 diabetes, while a high intake of fruits, vegetables, and dietary fiber can decrease type 2 diabetes risk. In 2002 and 2003, the U.S. Preventive Services Task Force (USPSTF) made recommendations on counseling to improve physical activity and healthful diet based on two separate systematic reviews of the literature. We undertook the current review to assist the USPSTF in updating these recommendations. This review combined both topics and evaluates the effectiveness and adverse effects of physical activity and dietary counseling interventions to prevent cardiovascular disease (CVD) in adults. In addition, this review focuses on the effectiveness of behavioral counseling as primary prevention for CVD and therefore does not include counseling interventions targeted to persons with known CVD, diabetes, hypertension, or dyslipidemia. Trials focusing on weight loss or weight management in adults are addressed in a separate USPSTF review on adult obesity, which is currently being updated.