Your body is an elegant machine that requires a constant supply of fuel. That fuel comes in the form of food, and when you eat right, your body performs well. Eat too much, too little or the wrong type of food, however, and you can start to develop health issues. To ensure good health, get enough calories every day -- not too many, not too few -- and eat nutritionally rich food.
Defining Calories
Calories aren't bad for you. In fact, you need them to survive. A calorie is a unit of energy, and your body requires energy to keep your organs and systems functioning. A food's calorie count tells you how much energy that food will give you. Carbohydrates and protein generally have four calories per gram, and fat has nine calories. Peanuts are high in all three, and they have 427 calories in a half cup of nuts. Lettuce, on the other hand, is low in carbohydrates, protein and fat. A cup of shredded lettuce only contains 10 calories. It doesn't necessarily matter how much food you eat -- what's important is that you get enough calories to keep your body running, without eating too many calories that will be stored as fat.
Calories and Nutrients
Calories are an important measurement of a food's usefulness to your body, but calories don't denote nutritional value. Your body also needs vitamins and minerals to stay healthy. Some foods, like soda, are high in calories but low in nutrients; others, like spinach, are high in nutrients and low in calories. You must balance your diet so you're getting the correct amount of each. To help you determine how many calories and nutrients you need, the U.S. Department of Agriculture has published recommendations called the Dietary Guidelines for Americans.
Determining Recommended Intake
The amount of calories you need varies based on gender, age and level of activity on a daily basis. For example, an 8-year-old girl needs 1,400 to 1,800 calories per day to maintain healthy body function. A 19-year-old guy needs 2,600 to 3,000 calories. You can consult the USDA's recommendations to get a general idea of your needs, or you can calculate them with an online tool. To find out exactly how many calories you should be eating each day, consult a registered dietitian or your doctor, who can make recommendations based on your physical activity and general health.
Risks From Over- and Undereating
It's important to stick to your recommended calorie intake. If you eat too many calories, they're stored in your body as fat, which can lead to weight gain. Overweight people have higher risks of type 2 diabetes, heart disease, stroke, cancer, osteoarthritis, pregnancy complications and more.
Undereating is equally dangerous. If you don't consume enough calories, your body won't have enough energy to function. At first, this can lead to sluggishness and fatigue. After a time it will lead to nutritional deficiencies, because if you're not eating enough food, it's difficult to get enough vitamins and minerals. Over time, undereating will weaken your immune system and can interfere with women's fertility and bone health.
References
- KidsHealth: Learning About Calories
- U.S. Department of Health and Human Services: A Healthier You -- Calories + Nutrients = Food
- U.S. Department of Agriculture: MyPyramid Food Intake Pattern Calorie Levels
- U.S. Weight-Control Information Network: Do You Know the Health Risks of Being Overweight?
- U.K. National Health Service: Underweight Adults
- MayoClinic.com: Calorie Calculator
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