Overview & Description
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 tostay alive and to move. The nutrients that provide calories in food arelimited to fat, protein, and carbohydrates.These 3 nutrients can be found in foods in allof the major food groups. Foods may have one or more of these nutrients.Even though it is not a nutrient, alcohol has calories too.
Each nutrient provides different amounts of calories per gramto the body.
These figures are used to calculate calories per serving.If a food is made of only fat, and contains 9 grams of fat, the caloriesin the product equals: 9 grams fat x 9 cal/gram of fat = 81 calories. On theother 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 plus4 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. Thesenutrients do not supply calories, however. When foods supply mainly caloriesand few nutrients, they are known as “calorie-dense.” When foodssupply calories along with vitamins and minerals, they are knownas “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 dailydiet. Federal dietary guidelines are issued by the US Department ofAgriculture and the Department of Health and Human Services. Theseguidelines recommend a diet that gets most of its calories from wholegrain products, fresh vegetables and fruits, lowfat milk products, leanmeats, fish, poultry, and dried beans.
The Food Guide Pyramid acts as a tool to help individualsfollow these dietary guidelines. In addition, the American HeartAssociation recommends a diet where:
The body’s need for energy and fuel never stops. Eachperson needs a certain amount of calories to fuel the body.The specific amount of calories depends on many factors. These include:
Once a person is an adult, energy, which means calorie, needsdrop 2% for each decade. Eating more calories than are needed usuallyresults in weight gain. Eating less than the required calories usuallyresults in weight loss.
Active men and teenaged boys needabout 2,800 calories a day to fuel their bodies enough. Exact calorieneeds for each person depends on the factors listed above. Following theFood Guide Pyramid,for this group, 2,800 calories would equal about:
Active women, teenaged girls, children, andless active men need about 2,200 calories to fuel their bodieswell. Following the Food Guide Pyramid,for this group, 2,200 calories equate to:
Less active women and some older adults needabout 1,600 calories to fuel their bodies. Following theFood Guide Pyramid,for this group, 1,600 calories would equate to:
Functions and Sources
How does the nutrient affect the body?
Carbohydrates, proteins, and fats all provide energy to thebody in the form of calories. These nutrients are released from foodsduring digestion. Then they are absorbed into the blood stream andchanged to glucose, which is another name for blood sugar. Glucoseis what the body actually uses as energy. Energy that the body doesnot need right away gets stored. Some is stored as fat. The rest isstored in the liver and muscles as glycogen, which is the stored formof glucose. The body can use these stores at a later time for energy.
Article type: xmedgeneral