1. Health
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

What's a Calorie, Anyway?


Updated February 15, 2014

Weight Loss 101

The official definition of a calorie is the amount of heat needed to raise the temperature of a liter of water one degree.

A calorie isn't actually a tangible thing, but a unit of measurement. Calories measure the energy contained in food and beverages we consume.

Calories are found in four components of foods: fat, carbohydrates, protein and alcohol. Fat contains twice the number of calories as carbohydrate or protein.

What do Calories Do?

Eating calories is comparable to filling up your gas tank on your car. The food we eat and beverages we drink become the fuel that runs our bodies.

Despite popular diets that suggest carbs or fat are far more important, calories definitely still count. If you "overload your tank," you will find yourself gaining weight.

How do Calories Become Fat?

We all have a basal caloric need. This is what our bodies require each day to perform minimal functions, including keeping our organs running.

When you are in excess of that caloric need, your body doesn't have any choice but to do something with those extra calories. It puts them in storage in the form of fat.

In other words, calories turn into fat when they're sitting around doing nothing. For about every 3,500 calories you are in excess of your caloric needs, you will gain approximately one pound.

How Many Calories do I Need?

The USDA daily recommended caloric intake for the average American maintaining their weight is 2,000 calories. The average recommended caloric intake for losing weight is about 1,500 calories a day.

Your individual calorie needs depend on several factors such as your activity level and metabolism.

You can calculate your Basal Metabolic Rate to assess how many calories you need to eat each day. The formula considers both your weight and activity level.

Once you do this, you can begin identifying ways to cut back on the calories that are in excess of your needs.

Learn to Count Calories to Lose Weight

You will need to cut or burn about 3,500 calories to lose approximately one pound.

By using a calorie content database such as Calorie Count Plus, you can track your caloric intake and find ways to cut back.

This is best achieved by cutting some calories from your regular diet with simple changes, such as choosing reduced-calorie beverages and burning additional calories with exercise.

Reducing your caloric intake by and/or burning a total of 500 calories a day will lead to an average of one pound lost each week, a healthy and sustainable rate at which to lose weight.

How Low is Too Low?

You may assume the more weight you need to lose, the more calories you should immediately cut. It's actually the other way around: The more you weigh now, the more calories you can -- and should -- eat.

As you lose weight, you should cut more calories. By keeping an accurate food and beverage diary and regularly re-calculating your BMR, you will be able to adjust your intake as needed.

While you may find a number of 1,200 calorie diets around, it's important to remember that cutting your calories too low may actually lead to weight plateaus. (There is a "starvation mode" phenomenon where your body actually withholds the calories you take in for later use because it "thinks" you're starving.)

Following a diet of just 1,200 calories a day would almost certainly mean you would not meet your daily nutrition requirments. Plus, if you do try to make such a severe calorie restriction, you're likely to feel hungry most of the time.

While you may lose a lot of weight, very quickly, by cutting so many calories, it's nearly impossible to sustain this type of diet for very long.

Never attempt to follow a diet of less than 1,200 calories a day unless you are instructed to do so under a doctor's supervision.


The U.S. Department of Health and Human Services. A Healthier You - Chapter 5. A Calorie is a Calorie, or Is It?. DHHS. 9 Oct. 2006. 23 July 2007.

Continue: Should I Follow a Diet?

More Weight Loss 101

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.