If you’re like many American’s you’ve tried the “calorie counting approach” to losing weight at some point in your life. Perhaps you’ve meticulously scribbled down calorie amounts in a notebook and tallied up your daily totals in a notebook, or maybe you use a mobile app to do the hard work for you. But have you ever stopped to think about how the number of calories is actually determined in the foods you eat?
What are Calories?
Before trying to count them, it’s a good idea to understand what calories really are. We simply call them “calories,” but the scientific name for them is kilocalories, which are made up of 1,000 scientific calories. This is the amount of energy your body needs to raise the temperature of a kilogram of water by one degree Celsius. The calories referenced on food packages are 1,000 times greater than the calories you dealt with back in chemistry and physics classes in school.
Calories on Food Labels
What’s presented on your food labels today was established by the Nutrition Labeling and Education Act of 1990 (NLEA). This act requires packaged food manufacturers to print nutrition information, including the number of calories, on packaging in a standard format.
The caloric values on packaged food are estimations that are calculated by adding together the calories contained in the nutrients that contain energy, which are proteins, carbs, fats, and alcohol. Fiber is not usually included in this calculation because only some fiber is soluble, while other types of fiber are insoluble.
According to Jim Painter, a University of Illinois assistant professor of food science and human nutrition:
The Atwater system uses the average values of 4 Kcal/g for protein, 4 Kcal/g for carbohydrate, and 9 Kcal/g for fat. Alcohol is calculated at 7 Kcal/g. (These numbers were originally determined by burning and then averaging.) Thus the label on an energy bar that contains 10 g of protein, 20 g of carbohydrate and 9 g of fat would read 201 kcals or Calories.
Inaccuracies in Calorie Counts
However, numerous studies have come out to show that the calorie counts that we know and depend on in our diets are actually inaccurate. According to a Business Insider report, figuring out the actual calorie content in foods requires feeding experiments.
Not all of the calories in food are digested and absorbed into the body, which is a problem with the Atwater system. It also doesn’t take into account the type of food being consumed or the individual consuming the food. For example, a study published in the Journal of Clinical Nutrition uncovered that almonds actually have about 20 percent less calories than package labels claim.
Calories for Non-Packaged Food
Another question that often comes up in discussions of calories is how the calorie value of fresh foods, like fruits, vegetables, and meat, are determined. If you’d like to try a fun science experiment to measure calories in your food, check out the Science and Health Education Partnership at the University of California San Francisco.
The FDA has created posters for retail stores with nutrition information for popular fruits, vegetables, and fish. You can download these PDF documents to check these facts and figures for yourself. Check out the Exemptions/Voluntary Nutrition Labeling of Raw Fruits, Vegetables and Fish section of the FDA’s Nutrition Labeling guide to learn more about fresh food labeling.
Tips for Monitoring Your Calorie Intake
Whether you choose to obsess over calorie numbers or not, there are a lot of things you can do to keep your calorie intake at a reasonable level and maintain a healthy weight. Here are some tips to get started.
- Keep track of what you eat in a food diary or use a diet/fitness tracker device
- Divide up the calories you eat throughout the day
- Try natural fruit and vegetable concentrates to supplement your diet
- Pay attention to recommended portion sizes
- Eliminate calorie-rich sugary beverages and soda from your diet
- Try to burn more calories than you consume if you’re trying to lose weight