Friday, November 6, 2009

Daily Calorie Intake

Recommended daily calorie intake varies from person to person, but there are guidelines for calorie requirements you can use as a starting point.

UK Department of Health Estimated Average Requirements (EAR) are a daily calorie intake of 1940 calories per day for women and 2550 for men.

How many calories are needed each day can vary greatly depending on lifestyle and other factors.

Factors that affect your personal daily calorie needs include your age, height and weight, your basic level of daily activity, and your body composition.

In order to lose weight you need to eat less calories per day than your body needs. To lose 1lb a week you need a negative calorie balance of 500 calories per day. To lose weight at 2lb a week you need to reduce your calorie intake by 1000 calories a day.

What is a Calorie?

A calorie is a unit of energy. We tend to associate calories with food, but they apply to anything containing energy. For example, a gallon (about 4 liters) of gasoline contains about 31,000,000 calories.
Specifically, a calorie is the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (1.8 degrees Fahrenheit). One calorie is equal to 4.184 joules, a common unit of energy used in the physical sciences.

Most of us think of calories in relation to food, as in "This can of soda has 200 calories." It turns out that the calories on a food package are actually kilocalories (1,000 calories = 1 kilocalorie). The word is sometimes capitalized to show the difference, but usually not. A food calorie contains 4,184 joules. A can of soda containing 200 food calories contains 200,000 regular calories, or 200 kilocalories. A gallon of gasoline contains 31,000 kilocalories.

The same applies to exercise -- when a fitness chart says you burn about 100 calories for every mile you jog, it means 100 kilocalories. For the duration of this article, when we say "calorie," we mean "kilocalorie."