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6 - Nutrition and Fitness
In addition to exercise, nutrition plays a major role in attaining and maintaining
total fitness. Good dietary habits (see Figure 6-1 ) greatly enhance the ability
of soldiers to perform at their maximum potential. A good diet alone, however,
will not make up for poor health and exercise habits. This chapter gives basic
nutritional guidance for enhancing physical performance. Soldiers must know and
follow the basic nutrition principles if they hope to maintain weight control
as well as achieve maximum physical fitness, good health, and mental alertness.
Guidelines for Healthy Eating
Eating a variety of foods and maintaining an energy balance are basic guidelines
for a healthy diet. Good nutrition is not complicated for those who understand
these dietary guidelines.
To be properly nourished, soldiers should regularly
eat a wide variety of foods from the major food groups, selecting a variety of
foods from within each group. (See Figure 6-2.) A well-balanced diet provides
all the nutrients needed to keep one healthy.
Most healthy adults do not need
vitamin or mineral supplements if they eat a proper variety of foods. There are
no known advantages in consuming excessive amounts of any nutrient, and there
may be risks in doing so.
For soldiers to get enough fuel from the food they
eat and to obtain the variety of foods needed for nutrient balance, they should
eat three meals a day. Even snacking between meals can contribute to good nutrition
if the right foods are eaten.
Another dietary guideline is to consume enough
calories to meet one’s energy needs. Weight is maintained as long as the body
is in energy balance, that is, when the number of calories used equals the number
of calories consumed.
The most accurate way to control caloric intake is to
control the size of food portions and thus the total amount of food ingested.
One can use standard household measuring utensils and a small kitchen scale to
measure portions of foods and beverages. Keeping a daily record of all foods eaten
and physical activity done is also helpful.
Figure 6-3 shows the number of
calories burned during exercise periods of different types, intensities, and durations.
For example, while participating in archery, a person will burn 0.034 calories
per pound per minute. Thus, a 150-pound person would burn 5.1 calories per minute
(150 lbs. x 0.034 calories/minute/lb. = 5.1 calories/ minute) or about 305 calories/hour,
as shown in Figure 6-4. Similarly, a person running at 6 miles per hour (MPH)
will burn 0.079 cal./min./lb. and a typical, 150-pound male will burn 11.85 calories/minute
(150 lbs. x 0.079 cal./lb./min. = 11.85) or about 710 calories in one hour, as
shown in Figure 6-3.
To estimate the number of calories you use in normal daily
activity, multiply your body weight by 13 if you are sedentary, 14 if somewhat
active, and 15 if moderately active. The result is a rough estimate of the number
of calories you need to maintain your present body weight. You will need still
more calories if you are more than moderately active. By comparing caloric intake
with caloric expenditure, the state of energy balance (positive, balanced, or
negative) can be determined.
Avoiding
an excessive intake of fats is another fundamental dietary guideline. A high intake
of fats, especially saturated fats and cholesterol, has been associated with high
levels of blood cholesterol.
The blood cholesterol level in most Americans
is too high. Blood cholesterol levels can be lowered by reducing both body fat
and the amount of fat in the diet. Lowering elevated blood cholesterol levels
reduces the risk of developing coronary artery disease (CAD) and of having a heart
attack. CAD, a slow, progressive disease, results from the clogging of blood vessels
in the heart. Good dietary habits help reduce the likelihood of developing CAD.
It
is recommended that all persons over the age of two should reduce their fat intake
to 30 percent or less of their total caloric intake. The current national average
is 38 percent. In addition, we should reduce our intake of saturated fat to less
than 10 percent of the total calories consumed. We should increase our intake
of polyunsaturated fat, but to no more than 10 percent of our total calories.
Finally, we should reduce our daily cholesterol intake to 300 milligrams or less.
Figure 6-4 suggests actions commanders can take to support sound dietary guidelines.
Most of these actions concern dining-facility management. Concerns
for Optimal Physical Performance
Carbohydrates, in the form of glycogen
(a complex sugar), are the primary fuel source for muscles during short-term,
high-intensity activities. Repetitive, vigorous activity can use up most of the
carbohydrate stores in the exercised muscles.
The body uses fat to help provide
energy for extended activities such as a one-hour run. Initially, the chief fuel
burned is carbohydrates, but as the duration increases, the contribution from
fat gradually increases.
The intensity of the exercise also influences whether
fats or carbohydrates are used to provide energy. Very intense activities use
more carbohydrates. Examples include weight training and the APFT sit-up and push-up
events.
Eating foods rich in carbohydrates helps maintain adequate muscle-glycogen
reserves while sparing amino acids (critical building-blocks needed for building
proteins). At least 50 percent of the calories in the diet should come from carbohydrates.
Individual caloric requirements vary, depending on body size, sex, age, and training
mission. Foods rich in complex carbohydrates (for example, pasta, rice, whole
wheat bread, potatoes) are the best sources of energy for active soldiers.
Because
foods eaten one to three days before an activity provide part of the fuel for
that activity, it is important to eat foods every day that are rich in complex
carbohydrates. It is also important to avoid simple sugars, such as candy, up
to 60 minutes before exercising, because they can lead to low blood sugar levels
during exercise.
Soldiers often fail to drink enough water, especially when
training in the heat. Water is an essential nutrient that is critical to optimal
physical performance. It plays an important role in maintaining normal body temperature.
The evaporation of sweat helps cool the body during exercise. As a result, water
lost through sweating must be replaced or poor performance, and possibly injury,
can result. Sweat consists primarily of water with small quantities of minerals
like sodium. Cool, plain water is the best drink to use to replace the fluid lost
as sweat. Soldiers should drink water before, during, and after exercise to prevent
dehydration and help enhance performance. Figure 6-5 shows recommendations for
fluid intake when exercising.
Sports drinks, which are usually simple carbohydrates
(sugars) and electrolytes dissolved in water, are helpful under certain circumstances.
There is evidence that solutions containing up to 10 percent carbohydrate will
enter the blood fast enough to deliver additional glucose to the active muscles.
This can improve endurance.
During prolonged periods of exercise (1.5+ hours)
at intensities over 50 percent of heart rate reserve, one can benefit from periodically
drinking sports drinks with a concentration of 5 to 10 percent carbohydrate. Soldiers
on extended road marches can also benefit from drinking these types of glucose-containing
beverages. During intense training, these beverages can provide a source of carbohydrate
for working muscles. On the other hand, drinks that exceed levels of 10 percent
carbohydrate, as do regular soda pops and most fruit juices, can lead to abdominal
cramps, nausea, and diarrhea. Therefore, these drinks should be used with caution
during intense endurance training and other similar activities.
Many people
believe that body builders need large quantities of protein to promote better
muscle growth. The primary functions of protein are to build and repair body tissue
and to form enzymes. Protein is believed to contribute little, if any, to the
total energy requirement of heavy-resistance exercises. The recommended dietary
allowance of protein for adults is 0.8 grams per kilogram of body weight. Most
people meet this level when about 15 percent of their daily caloric intake comes
from protein. During periods of intense aerobic training, one’s need for protein
might be somewhat higher (for example, 1.0 to 1.5 grams per kilogram of body weight
per day). Weight lifters, who have a high proportion of lean body mass, can easily
meet their protein requirement with a well-balanced diet which has 15 to 20 percent
of its calories provided by protein. Recent research suggests that weight trainers
may need no more protein per kilogram of body weight than average, non-athletic
people. Most Americans routinely consume these levels of protein, or more. The
body converts protein consumed in excess of caloric needs to fat and stores it
in the body.
 Nutrition
in the Field
Soldiers in the field must eat enough food to provide them
with the energy they need. They must also drink plenty of water or other non-alcoholic
beverages. The “meal, ready to eat” (MRE) supplies the needed amount of carbohydrates,
protein, fat, vitamins, and minerals. It is a nutritionally adequate ration when
all of its components are eaten and adequate amounts of water are consumed. Because
the foods are enriched and fortified with vitamins and minerals, each component
is a major source of nutrients. Soldiers must eat all the components in order
to get the daily military recommended dietary allowances (MRDA) and have an adequate
diet in the field. Soldiers who are in weight control programs or who are trying
to lose weight can eat part of each RE item, as recommended by dietitians. |
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