The important role of nutrition in overall health is widely recognized. As a member of the Navy, you must be healthy to perform your professional duties. Part of maintaining a healthy lifestyle starts with eating a well-balanced diet and maintaining a good fitness regimen. Many people in the Navy and Marine Corps do not maintain a proper daily diet. As a Hospital Corpsman, you may be responsible for providing nutritional counseling and, perhaps, even motivation. You have an added responsibility to observe for additional nutritional needs and omissions and to advise your shipmates when necessary. If you stay healthy and energetic, the knowledge and experience you share and the example you set may help your shipmates adopt and maintain a healthier lifestyle.

Balancing energy intake and expenditure can be difficult, both when activity levels are high as well as when they are very low. Typically, body weight remains constant when energy intake equals expenditure (fig. 9-1). The energy balance equation can be "unbalanced" by changing energy intake, energy expenditure, or both. To gain or lose 1 pound requires that approximately 3,500 extra calories be consumed or burned.

FOOD CLASSIFICATION

LEARNING OBJECTIVE: Identify the components of good nutrition.

Foods are substances from animal and plant sources that yield heat and energy when ingested and absorbed by the body. Food nutrients build and renew tissues and regulate the body processes. The unit commonly used for describing energy intake and energy expenditure is the calorie. Good food sources contain substantial amounts of nutrients in relation to caloric content and provide upwards of 10 percent of the U.S. Recommended Dietary Allowance for each specific nutrient. Most people can get enough of each required nutrient daily by eating a wide variety of foods.

PROTEINS
Proteins are the "building blocks" of the body and provide important required nutritive elements. Proteins are needed for growth, maintenance, and replacement of body cells, and they form hormones and enzymes used to regulate body processes. Extra protein is either used to supply energy or is changed into body fat. Found in both the animal and plant kingdoms, all proteins are composed of amino acids. Some amino acids are absolutely essential to maintain life and are necessary for repair, growth, and body development. Of the approximately 20 amino acids,

Figure 9-1.-Balancing energy intake.

our body can produce all but nine. These nine amino acids are termed "essential amino acids." We must get them from food, and we need all nine at one time so our body can use them effectively.

Proteins, which promote tissue growth and renewal, have long been recognized as the main structural unit of all living cells. Each gram (g) of protein yields 4 calories in the process of metabolism. Although proteins yield energy, they are an expensive source. If sufficient carbohydrates are not supplied, the body will use protein for energy requirements. This protein may be obtained from muscle tissue, producing the "wasting effect" of long-term starvation and some diseases.

A constant protein source is required in the daily diet. The normal daily protein intake for adults should be 0.8 gram per kilogram (g/kg) (2.2 lbs) of body weight, or 12 percent of the total caloric intake. Pregnant women require an additional 10 grams of protein a day over the normal daily intake.

Proteins play an important role in recovering from fractures, burns, and infections. They are also important in healing wounds and recovering from surgical procedures. In cases of recovery, protein intake should be increased in accordance with the severity of the condition, and carbohydrates and fats can be added liberally. While proteins can supply energy, they are not a main source of energy like carbohydrates and fat.

Ideally, the patient should receive protein by mouth; however, it is sometimes necessary to meet the minimum requirements parenterally. Glucose parenteral solution, given during an acute emergency period, will prevent some loss of protein. Protein deficiency may stunt growth, promote a secondary anemia, or induce nutritional edema. Dietary sources of protein and the nine essential amino acids are milk, yogurt, eggs, meats, fish, cheese, poultry, peanut butter, legumes, and nuts. Protein from plant sources is best when combined with animal protein, such as milk plus peanut butter, or when legumes are combined with grains, such as Navy beans plus rice.