With all the bad press that calories and fat receive, you'd think that they are bad things. While it's true that many people eat far more fat and calories than is necessary, we all need a certain amount of fat and calories for growth and activities. Knowing the difference between calories and calories from fat will help you make wise food choices.
What Is a Calorie?
A calorie is the basic unit of energy measurement. The energy you get from food and the energy you expend from exercise are measured in calories. You can eat an apple and receive about 55 calories of energy, and you can take a walk for about 15 minutes and burn 55 calories.
According to the University of Maryland Medical Center, calories come from three general sources: carbohydrates, proteins and fats. One gram of carbohydrates has four calories. One gram of protein has four calories. One gram of fat has nine calories. The main difference between calories from fat and calories from the other two sources is that fat is twice as dense in calories.
What Are Fats?
Fats are also known as lipids; they are nutrients that your body uses as building blocks for nerve tissues and hormones. Fat can also be used as fuel by the body. When a person eats fat that is not used as building blocks or fuel, it is stored by the body in fat cells. From your body's point of view, it's saving for the future, planning ahead for a time when fat may not be available.
Calculating Fat Calories
Fat has twice as many calories per gram than carbohydrate or protein. That's why foods with the same serving size may have different numbers of calories. A half cup of vanilla ice cream contains 178 calories from three sources: 2 grams of protein (2 x 4 = 8 calories), 15.5 grams of carbohydrate (15.5 x 4 = 62 calories), and 12 grams of fat (12 x 9 = 108 calories). A high-fat food has more calories than a food with protein or carbohydrates. Consider the same serving size of a half cup of carrots: 1 gram of protein (1 x 4 = 4 calories), 8 grams of carbohydrate (8 x 4 = 32 calories), and 0 grams of fat. There are about 36 calories in a half cup of carrots.
The Key Difference
The difference between fat calories and other calories is more significant when addressing excess calories, calories that your body does not have to use immediately for energy. A fat calorie can be stored as fat by the body more easily than a carbohydrate or a protein calorie. If you eat 100 excess calories of nothing but carbohydrates, your body will expend about 25 percent of those calories just to convert and store the excess calories. That means it will store 75 calories as fat. If you eat 100 excess calories of fat, the fat doesn't need to be converted before being stored. Your body will use about three calories of the 100 to store the other 97 fat calories as fat.