Dieting For Dummies
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Calories are simply a way to measure the energy in food and the energy released in the body. Although the technically correct name is kilocalorie, everyone, including dietitians, uses the shorter "calorie."

One calorie is the amount of energy necessary to raise the temperature of 1 gram of water by 1 degree Centigrade. You expend about 1 calorie per minute when sitting relaxed. That’s about the same amount of heat released by a candle or a 75-watt light bulb.

Calories are rounded on food labels, so when you multiply the grams of protein, carbohydrate, or fat, you may come out with a different value than appears on the label. Foods that contain 50 calories or fewer are rounded to the nearest 5-calorie increment; foods with more than 50 calories are rounded to the nearest 10-calorie increment.

Foods that have fewer than 5 calories can be listed as having 0 calories. Although you may think that this rounding seems misleading or inaccurate, keep in mind that a 10-calorie difference is actually negligible in the grand scheme of things.

A calorie isn’t a nutrient, but certain nutrients provide calories. Protein, carbohydrate, and fat make up the calorie contents of various foods. Although not considered a nutrient, alcohol also provides calories. In fact, one gram of

  • Protein contains 4 calories

  • Carbohydrate contains 4 calories

  • Fat contains 9 calories

  • Alcohol contains 7 calories

The remaining nutrients — water, minerals, and vitamins — do not provide calories, nor does fiber or cholesterol.

Few foods and beverages are 100 percent of any one nutrient. Most foods and beverages are a combination of protein, fat, and carbohydrate (and sometimes alcohol), so a food’s calorie count is the sum of the calories provided by each nutrient. See how it works:

A bowl of chicken noodle soup contains 3 grams of protein, 7 grams of carbohydrate, and 2 grams of fat for a total of 58 calories:

3 grams protein x 4 calories/gram = 12 calories
7 grams carbohydrate x 4 calories/gram = 28 calories
2 grams fat x 9 calories/gram = 18 calories
Total = 58 calories

Even though most foods are made up of two or more nutrients, foods are categorized by their predominant nutrient. For example, a bagel and a bowl of cereal are considered carbohydrate foods even though they also contain protein and, sometimes, fat. Even though a chicken breast is considered a protein food, not all of its calories come from protein. Chicken also contains fat, which contributes calories.

Not all calories are created equal. Foods that are considered empty-calorie foods really have nothing in them as far as nutrition goes, except for calories. Sugary foods, such as candy, are prime examples. When you’re restricting calories, you can make some room for empty-calorie foods but don’t build your diet on them. If you do, you’ll miss out on valuable minerals, fiber, and vitamins.

The opposite of empty-calorie foods are nutrient-dense foods. Calorie for calorie, they pack a solid nutrition punch by providing a good amount of vitamins, minerals, and/or fiber in comparison to the number of calories they provide. In other words, you get a big nutrition bang for your caloric buck.

An example of a nutrient-dense food is an orange. For a mere 60 calories, you get about 3 grams of fiber, 100 percent of your daily vitamin C requirement, and a good amount of folic acid plus a spectrum of other micronutrients and phytochemicals, such as antioxidants.

About This Article

This article is from the book:

About the book authors:

Jane Kirby, RD is a registered dietitian and member of the American Dietetic Association. She is the food and nutrition editor of Real Simple magazine and owner of The Vermont Cooking School, IncTM in Charlotte, Vermont. Jane is the former editor of Eating Well magazine and the food and nuitrition editor for Glamour. She served on the dietetics staff of the Massachusettes General Hospital in Boston, where she  completed graduate work in nutrition. She holds a Bachelor of Science degree from Marymount College.

The American Dietetic Association is the world’s largest group of nutrition and health professionals. As an advocate of the profession, the ADA serves the public by promoting optimal nutrition, health, and well-being.

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