Physical activity is the other side of the calorie balance equation and should be considered when addressing weight management. In 2008, the U.S. Department of Health and Human Services released a comprehensive set of physical activity recommendations for Americans ages 6 years and older. Weight management along with health outcomes, including premature (early) death, diseases (such as coronary heart disease, type 2 diabetes, and osteoporosis), and risk factors for disease (such as high blood pressure and high blood cholesterol) were among the outcomes considered in developing the 2008 Physical Activity Guidelines for Americans.Getting adequate amounts of physical activity conveys many health beneits independent of body weight.
Strong evidence supports that regular participation in physical activity also helps people maintain a healthy weight and prevent excess weight gain. Further, physi-cal activity, particularly when combined with reduced calorie intake, may aid weight loss and maintenance of weight loss. Decreasing time spent in sedentary behav-iors also is important as well. Strong evidence shows that more screen time, particularly television viewing, is associated with overweight and obesity in children, adolescents, and adults. Substituting active pursuits for sedentary time can help people manage their weight and provides other health beneits.
The 2008 Physical Activity Guidelines for Americans provides guidance to help Americans improve their health, including weight management, through appropriate physical activity (see Table 2-5). The amount of physical activity necessary to successfully maintain a healthy body weight depends on calorie intake and varies considerably among adults, includ-ing older adults. To achieve and maintain a healthy body weight, adults should do the equivalent of 150 minutes of moderate-intensity aerobic activity each week. If necessary, adults should increase their weekly minutes of aerobic physical activity gradually over time and decrease calorie intake to a point where they can achieve calorie balance and a healthy weight. Some adults will need a higher level of physical activ-ity than others to achieve and maintain a healthy body weight. Some may need more than the equivalent of 300 minutes per week of moderate-intensity activity.
For children and adolescents ages 6 years and older, 60 minutes or more of physical activity per day is rec-ommended. Although the Physical Activity Guidelines do not include a speciic quantitative recommendation for children ages 2 to 5 years, young children should play actively several times each day. Children and adolescents are often active in short bursts of time rather than for sustained periods of time, and these short bursts can add up to meet physical activity needs. Physical activities for children and adolescents of all ages should be developmentally appropriate and enjoyable, and should offer variety.
Principles for Promoting calorie Balance and weight Management
To address the current calorie imbalance in the United States, individuals are encouraged to become more conscious of what they eat and what they do. This means increasing awareness of what, when, why, and how much they eat, deliberately making better choices regarding what and how much they consume, and seeking ways to be more physically active. Several behaviors and practices have been shown to help people manage their food and beverage intake and calorie expenditure and ultimately manage body weight. The behaviors with the strongest evidence related to body weight include:
• focus on the total number of calories consumed. Maintaining a healthy eating pattern at an appropriate calorie level within the AMDR is advisable for weight management. Consuming an eating pattern low in calorie density may help to reduce calorie intake and improve body weight outcomes and overall health.
• Monitor food intake. Monitoring intake has been shown to help individuals become more aware of what and how much they eat and drink. The Nutrition Facts label found on food packaging pro-vides calorie information for each serving of food or beverage and can assist consumers in monitor-ing their intake. Also, monitoring body weight and physical activity can help prevent weight gain and improve outcomes when actively losing weight or maintaining body weight following weight loss.
• when eating out, choose smaller portions or lower-calorie options. When possible, order a small-sized option, share a meal, or take home part of the meal. Review the calorie content of foods and beverages offered and choose lower-calorie options. Calorie information may be available on menus, in a pamphlet, on food wrappers, or online. Or, instead of eating out, cook and eat more meals at home.
• Prepare, serve, and consume smaller portions of foods and beverages, especially those high in calories. Individuals eat and drink more when provided larger portions. Serving and consuming smaller portions is associated with weight loss and weight maintenance over time.
• eat a nutrient-dense breakfast.Not eating breakfast has been associated with excess body weight, especially among children and adolescents. Consuming breakfast also has been associated with weight loss and weight loss maintenance, as well as improved nutrient intake.
• limit screen time. In children, adolescents, and adults, screen time, especially television viewing, is directly associated with increased overweight and obesity. Children and adolescents are encouraged to spend no more than 1 to 2 hours each day watching televi-sion, playing electronic games, or using the computer (other than for homework). Also, avoid eating while watching television, which can result in overeating.
Research has investigated additional principles that may promote calorie balance and weight manage-ment. However, the evidence for these behaviors is not as strong. Some evidence indicates that beverages are less illing than solid foods, such that the calories from beverages may not be offset by reduced intake of solid foods, which can lead to higher total calorie intake. In contrast, soup, par-ticularly broth or water-based soups, may lead to decreased calorie intake and body weight over time. Further, replacing added sugars with non-caloric sweeteners may reduce calorie intake in the short-term, yet questions remain about their effectiveness as a weight management strategy. Other behaviors have been studied, such as snacking and frequency of eating, but there is currently not enough evidence to support a speciic recommendation for these behaviors to help manage body weight.
Improving Public health through diet and Physical activity
This chapter has focused on the two main elements in calorie balance calories consumed and calories expended. These elements are critical for achiev-ing and maintaining an appropriate body weight throughout the lifespan, and they also have broader implications for the health of Americans.
Although obesity is related to many chronic health conditions, it is not the only lifestyle-related public health problem confronting the Nation. Eating pat-terns that are high in calories, but low in nutrients can leave a person overweight but malnourished. Nutritionally unbalanced diets can negatively affect a person’s health regardless of weight status. Such diets are related to many of the most common and costly health problems in the United States, particularly heart disease and its risk factors and type 2 diabetes. Similarly, a sedentary lifestyle increases risk of these diseases. Improved eat-ing patterns and increased physical activity have numerous health benefits beyond maintaining a healthy weight.
Improved nutrition, appropriate eating behaviors, and increased physical activity have tremendous potential to decrease the prevalence of overweight and obesity, enhance the public’s health, reduce morbidity and premature mortality, and reduce health care costs.
