Physical Activity

Regular physical activity and physical fitness make important contributions to one’s health, sense of well-being,and maintenance of a healthy body weight. Physical activity is defined as any bodily movement produced by skeletal muscles resulting in energy expenditure. In contrast, physical fitness is a multi-component trait related to the ability to perform physical activity. Maintenance of good physical fitness enables one to meet the physical demands of work and leisure comfortably. People with higher levels of physical fitness are also at lower risk of developing chronic disease. Conversely, a sedentary lifestyle increases risk for overweight and obesity and many chronic diseases, including coronary artery disease, hypertension, type 2 diabetes, osteoporosis, and certain types of cancer. Overall, mortality rates from all causes of death are lower in physically active people than in sedentary people. Also, physical activity can aid in managing mild to moderate depression and anxiety.

Engage in regular physical activity and reduce sedentary activities to promote health, psychological wellbeing, and a healthy body weight.

  • To reduce the risk of chronic disease in adulthood: Engage in at least 30 minutes of moderate-intensity physical activity, above usual activity, at work or home on most days of the week.
  • For most people, greater health benefits can be obtained by engaging in physical activity of more vigorous intensity or longer duration.
  • To help manage body weight and prevent gradual, unhealthy body weight gain in adulthood: Engage in approximately 60 minutes of moderate- to vigorous-intensity activity on most days of the week while not exceeding caloric intake requirements.
  • To sustain weight loss in adulthood: Participate in at least 60 to 90 minutes of daily moderate-intensity physical activity while not exceeding caloric intake requirements. Some people may need to consult with a healthcare provider before participating in this level of activity.

Achieve physical fitness by including cardiovascular conditioning, stretching exercises for flexibility, and resistance exercises or calisthenics for muscle strength and endurance.

  • Children and adolescents. Engage in at least 60 minutes of physical activity on most, preferably all, days of the week.
  • Pregnant women. In the absence of medical or obstetric complications, incorporate 30 minutes or more of moderate-intensity physical activity on most, if not all, days of the week. Avoid activities with a high risk of falling or abdominal trauma.
  • Breastfeeding women. Be aware that neither acute nor regular exercise adversely affects the mother’s ability to successfully breastfeed.
  • Older adults. Participate in regular physical activity to reduce functional declines associated with aging and to achieve the other benefits of physical activity identified for all adults.

Elevating the level of daily physical activity may also provide indirect nutritional benefits. A sedentary lifestyle limits the number of calories that can be consumed without gaining weight. The higher a person’s physical activity level, the higher his or her energy requirement and the easier it is to plan a daily food intake pattern that meets recommended nutrient requirements.

Proper hydration is important when participating in physical activity. Two steps that help avoid dehydration during prolonged physical activity or when it is hot include:

  • consuming fluid regularly during the activity and
  • drinking several glasses of water or other fluid after the physical

Weight Management

The prevalence of overweight among children and adolescents has increased substantially; it is estimated that as many as 16 percent of children and adolescents are overweight, representing a doubling of the rate among children and tripling of the rate among adolescents. A high prevalence of overweight and obesity is of great public health concern because excess body fat leads to a higher risk for premature death, type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease, stroke, gall bladder disease, respiratory dysfunction, gout, osteoarthritis, and certain kinds of cancers.

Ideally, the goal for adults is to achieve and maintain a body weight that optimizes their health. However, for obese adults, even modest weight loss (e.g., 10 pounds) has health benefits, and the prevention of further weight gain is very important. For overweight children and adolescents, the goal is to slow the rate of weight gain while achieving normal growth and development. Maintaining a healthy weight throughout childhood may reduce the risk of becoming an overweight or obese adult. Eating fewer calories while increasing physical activity are the keys to controlling body weight.

People at a healthy weight should strive to maintain their weight, and underweight individuals may need to increase their weight.

  • To maintain body weight in a healthy range, balance calories from foods and beverages with calories expended.
  • To prevent gradual weight gain over time, make small decreases in food and beverage calories and increase physical activity.
  • Those who need to lose weight. Aim for a slow, steady weight loss by decreasing calorie intake while maintaining an adequate nutrient intake and increasing physical activity.
  • Overweight children. Reduce the rate of body weight gain while allowing growth and development. Consult a health care provider before placing a child on a weight reduction diet.
  • Pregnant women. Ensure appropriate weight gain as specified by a health care provider.
  • Breastfeeding women. Moderate weight reduction is safe and does not compromise weight gain of the nursing infant.
  • Overweight adults and overweight children with chronic diseases and/or on medication. Consult a health care provider about weight loss strategies prior to starting a weight reduction program to ensure appropriate management of other health conditions.


The body’s main energy source, it helps power the body and digest food. The main form of carbohydrate used to generate energy is glucose. If more calories than the body needs are consumed, glucose is converted to body fat.

Carbohydrates include sugars, starches and fiber. They constitute a large part of foods such as rice, noodles, bread, and other grain-based products. Carbohydrates may be classified chemically as monosaccharides, disaccharides, or polysaccharides depending on the number of monomer (saccharide or sugar) units they contain. Monosaccharides, disaccharides, and polysaccharides contain one, two, and three or more sugar units, respectively.

Carbohydrates are not essential nutrients (with the likely exception of fiber), but are typically an important part of the human diet. While it would not be accurate to categorize all carbohydrates as “bad” nutritionally, some carbohydrate sources may well have deleterious effects on health, especially when consumed in large quantities. Highly processed carbohydrates as well as fructose consumed in large quantities have been implicated in negative health outcomes.


Nutrition consumption of food and how the body uses the food for growth, energy, and healing of damaged tissues. Nutrition involves digestion of food, absorption, storage and use of nutrients, and excrement of waste through urine or bowel movements.

The human body contains chemical compounds, such as water, carbohydrates, amino acids, fatty acids, and nucleic acids. These compounds in turn consist of elements such as carbon, hydrogen, oxygen, nitrogen, phosphorus, calcium, iron, zinc, magnesium, manganese, and so on. All of these chemical compounds and elements occur in various forms and combination, both in the human body and in the plant and animal organisms that humans eat.

There are six major classes of nutrients:

  • Carbohydrates
  • Fats
  • Minerals
  • Proteins
  • Vitamins
  • Water

Most foods contain a mix of some or all of the nutrient classes, together with other substances, such as toxins of various sorts. Some nutrients can be stored internally, while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient.