Calories are a way of measuring the potential energy in foods.
They also measure the amount of energy, in units, that the body uses.
Food supplies calories to the body. The body burns calories to
stay alive and to move. The nutrients that provide calories in food are
limited to fat, protein, and carbohydrates.
These 3 nutrients can be found in foods in all
of the major food groups. Foods may have one or more of these nutrients.
Even though it is not a nutrient, alcohol has calories too.
Information
Each nutrient provides different amounts of calories per gram
to the body.
One gram of carbohydrate equals 4 calories.
One gram of protein equals 4 calories.
One gram of fat equals 9 calories.
One gram of alcohol equals 7 calories.
These figures are used to calculate calories per serving.
If a food is made of only fat, and contains 9 grams of fat, the calories
in the product equals: 9 grams fat x 9 cal/gram of fat = 81 calories. On the
other hand, if the food contained 2 grams of fat and 4 grams of protein,
the total calories would equal 34 (2 grams fat x 9 cal/gram = 18 calories plus
4 grams protein x 4 cal/gram = 16 calories, for a total of 34 calories).
Food offers more than just calories. It offers vitamins,
minerals, and water, which are also key nutrients in maintaining health. These
nutrients do not supply calories, however. When foods supply mainly calories
and few nutrients, they are known as "calorie-dense." When foods
supply calories along with vitamins and minerals, they are known
as "nutrient-dense." The key is to choose your calories wisely.
Choose foods that will provide a good balance of both calories and nutrients.
For a healthy diet, people need all 3 nutrients in their daily
diet. Federal dietary guidelines are issued by the US Department of
Agriculture and the Department of Health and Human Services. These
guidelines recommend a diet that gets most of its calories from whole
grain products, fresh vegetables and fruits, lowfat milk products, lean
meats, fish, poultry, and dried beans.
The Food Guide Pyramid acts as a tool to help individuals
follow these dietary guidelines. In addition, the American Heart
Association recommends a diet where:
carbohydrates supply 55 to 60% of the calories
fat calories make up less than 30% of the total (with less than
8% to 10 % from saturated fat)
The body's need for energy and fuel never stops. Each
person needs a certain amount of calories to fuel the body.
The specific amount of calories depends on many factors. These include:
weight
height
basal metabolic rate, called BMR, which is how many calories the body
burns at rest in 24 hours
age
body composition, which refers to how fat and muscle are distributed
in the body
physical condition and activity level
Once a person is an adult, energy, which means calorie, needs
drop 2% for each decade. Eating more calories than are needed usually
results in weight gain. Eating less than the required calories usually
results in weight loss.
Active men and teenaged boys need
about 2,800 calories a day to fuel their bodies enough. Exact calorie
needs for each person depends on the factors listed above. Following the
Food Guide Pyramid,
for this group, 2,800 calories would equal about:
11 servings from the bread group
5 servings of vegetables
4 servings of fruit
2-3 servings from the milk group (teens should have 3 servings)
3 servings (for a total of 7 ounces) from the meat group
Active women, teenaged girls, children, and
less active men need about 2,200 calories to fuel their bodies
well. Following the Food Guide Pyramid,
for this group, 2,200 calories equate to:
9 servings from the bread group
4 servings of vegetables
3 servings of fruit
2-3 servings from the milk group (pregnant and breastfeeding
women should get 3 servings, teenaged girls and young adults up to
age 24 should get 4 servings)
2 servings (for a total of 6 ounces) from the meat group.
Less active women and some older adults need
about 1,600 calories to fuel their bodies. Following the
Food Guide Pyramid,
for this group, 1,600 calories would equate to:
6 servings from the bread group
3 servings of vegetables
2 servings of fruit
2-3 servings from the milk group
2 servings (for a total of 5 ounces) from the meat group
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