What Are Calories? And Why Should You Care?

If you want to lose weight you need to know something about calories. You know that some foods have more than others. Fattening foods have more calories. Diet foods have fewer calories. But what are calories, really, and what do they have to do with you losing weight and keeping it off?

Calories are basically a measurement of heat. For example, if you are going to boil water you have to heat it. The amount of heat it takes is measured in calories.

A scientist will tell you that it takes one calorie to raise the temperature of one gram of water by one degree. (These are calories with a small “c”. Food Calories are with a large “C” and are actually 1000 small calories.) The interesting thing about calories is that the amount of heat never changes. If it takes 1000 calories to boil a pot of water today, it will take 1000 calories tomorrow, and it will take 1000 calories any time in the future to boil that same pot of water. It never changes. It doesn’t matter if the heat comes from a gas stove, or burning coal, or an electric heater, it still takes 1000 calories to boil that one pot of water.

You get calories from anything that makes heat. For example, there are calories in gasoline. Every gallon of gasoline will give you a certain number of calories. In fact there are about 31,000,000 calories in a gallon of gasoline. Gasoline burns hot, and that is a lot of heat, a lot of calories.

So what does this have to do with losing weight? Your food has calories, just like coal or gasoline or electricity. And just like there are a certain number of calories in a gallon of gasoline or a lump of coal, there are a certain number of calories in the food you eat.

You know that when you put gasoline in your car you are going to get a certain number of miles per gallon, depending on the car and how you drive. You might get 25 miles to the gallon. But you are not going to get 250 miles to the gallon no matter what kind of car you drive.

The same is true for your food. An apple has about 100 calories. A tablespoon of oil has 125 calories. A teaspoon of sugar has 15 calories. It is the same for you as it is for me, and it is the same today as it is tomorrow. Calories don’t change.

Now, when you take in food, you body has many uses for it. Some of it provides heat and keeps you warm. Some of it is used to make muscle. Some of it powers your heart and lungs. And each of these takes calories.

In the same way that your car gets 25 miles per gallon, and not 250 miles per gallon, you get a certain number of miles from an apple or from a cheeseburger. You can get about 15 minutes of exercise energy from an apple, and about two hours worth from a cheeseburger.

Pick any food. That food supplies a certain number of calories. Whether it is primarily fat or protein or carbohydrate doesn’t really change it. It still supplies a certain number of calories. When you eat something your body breaks it down and then uses it. It will use it for energy or it will use it to produce something the body needs. And when it is done doing those two things, it stores what is left.

Your body can store a very limited amount of sugar, maybe a few hundred calories. Anything left after that has to get stored as fat. And your body can store virtually unlimited amounts of fat.

Scientists have measured the number of calories in a pound of fat. There are 3500 calories in one pound of fat. So if you take in 3500 calories more than you use, you will gain one pound of fat. It doesn’t matter where the calories come from, whether protein or fat or carbohydrate, those 3500 extra calories will be turned into one pound of fat.

So beware of diets which claim that calories don’t count. Or that claim that you can eat all you want of certain types of food, and that if you avoid other types of food you cannot get fat. That just defies the laws of physics. It is just not true, and the people that claim that are either fooling themselves or trying to fool you. A calorie is a calorie is a calorie, whether it is fat or protein or carbohydrate.

Take in fewer calories than you use, and you will lose weight. Take in more than you use and you will gain weight. Now, that doesn’t mean you have to count calories. You don’t have to count calories, but somehow you have to come into proper balance.

Diets that don’t count calories accomplish the same goal somehow. Whether you use a point system, eat prepackaged meals, measure food by the ounce or gram, or control portion sizes, the effect is the same. Somehow you must take in less than your body uses and you lose weight. If you do not take in less than your body uses you will not lose weight.

If you are 20 pounds overweight you have eaten 70,000 calories more than you needed, and you stored it as fat. If you are 50 pounds overweight you ate 175,000 calories more than you needed. Fifty pounds is equivalent to 1,166 cans of soda, and now you are carrying it around with you. Think about that the next time you reach for a sugary snack.

There is really no magic to eating one type of food over another. Many scientific studies have proven that the weight loss from low carbohydrate diets is due to calorie restriction and not from the amount of fat or carbohydrate. While you should avoid excessive sugary snacks, you also need complex carbohydrates as part of a healthy diet.

It is very hard to lose weight and keep it off if you do not know what is in the food that you eat. The more you understand about food and what it is made of the easier it will be for you to lose weight and keep it off.

Whether you count them or not, calories are the key to permanent weight loss. Food is made of protein and carbohydrate and fat, and these have calories. Knowing this and using it can be your key to finally taking off that extra weight and keeping it off forever.

Copyright 2006 Dan Curtis, M.D.

Dan Curtis, M.D. is Assistant Professor of Medicine at the University of South Florida. He is the author of Dr. Dan’s Super Weight Loss Plan.
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