Counting calories: Get back to weight-loss basics

Your weight is a balancing act, and calories play a big role. Find out how calories determine your weight and ways you can best cut calories from your diet. By Mayo Clinic Staff

Despite all the diet strategies out there, weight management still comes down to the calories you take in versus those you burn off. Fad diets may promise you that avoiding carbs or eating a mountain of grapefruit is the secret to weight loss, but it's really all about calories.

Calories: Fuel for your body

Calories are the energy in food. Your body has a constant demand for energy and uses the calories from food to keep functioning. Energy from calories fuels your every action, from fidgeting to marathon running.

Carbohydrates, fats and proteins are the types of nutrients that contain calories and are the main energy sources for your body. The amount of energy in each varies. Proteins and carbohydrates have about 4 calories a gram, and fats have about 9 calories a gram. Alcohol also is a source of calories, providing about 7 calories a gram.

Regardless of where they come from, the calories you eat are either converted to physical energy or stored within your body as fat. These stored calories will remain in your body as fat unless you use them up, either by reducing calorie intake so that your body must draw on reserves for energy, or by increasing physical activity so that you burn more calories.

Tipping the scale: Cutting calories

Your weight is a balancing act, but the equation is simple: If you eat more calories than you burn, you gain weight.

Because 3,500 calories equals about 1 pound (0.45 kilogram) of fat, you need to burn 3,500 calories more than you take in to lose 1 pound. So if you cut 500 calories from your typical diet each day, you'd lose about 1 pound a week (500 calories x 7 days = 3,500 calories). It isn't quite this simple, however, and you usually lose a combination of fat, lean tissue and water. Also, because of changes that occur in the body as a result of weight loss, you may need to decrease calories further to continue weight loss.

Cutting calories

Cutting calories doesn't have to be difficult. In fact, it can be as simple as:

  • Skipping high-calorie, low-nutrition items
  • Swapping high-calorie foods for lower calorie options
  • Reducing portion sizes

Here's a closer look.

Jun. 19, 2012 See more In-depth