It sounds intuitive – consume more calories than you burn and you’ll gain weight. Eat less than your body burns and the pounds will drop off. However, some fitness, nutritionists, and health care professionals now think calorie counting is outdated and not the best approach for sustainable weight loss. So, what’s the story on counting calories – does it work or is there a better approach?
Calorie Counting: What is a Calorie Anyway?
Calories are the amount of energy your body extracts from food. Foods that are higher in calories provide more energy that your body can use than ones lower in calories. Of course, your body also expends energy, in the form of calories, when you exercise and to carry out the many functions your body does even at rest. Scientists describe the energy that food releases in terms of kilocalories, or thousands of calories. For example, an egg has 78,000 calories or 78 kilocalories. To simplify things, calories are used in everyday life to replace kilocalories.
To measure the calorie content of a food, scientists, at one time, used an instrument called a calorimeter. A calorimeter is a sealed container that has water surrounding it. To measure the calorie content, you burn the food within the sealed chamber and carefully measure the rise in temperature. A calorie (or kilocalorie) is the amount of energy, released by burning the food, that increases the temperature of one kilogram of water by one degree Celsius. A food that raises the temperature of the water more has a greater number of calories.
Calorie Counting Has Limitations
Although a calorimeter is the best measurement of calorie content that we have, it doesn’t take into account how a particular food is handled by your body. For example, if you measured the calorie content of pistachios in a calorimeter, you’d get a certain value. Yet, studies show your body doesn’t absorb all of the fats from nuts, like pistachios and almonds. The number of calories your body actually absorbs and uses is up to 30% lower because of the way your digestive tract handles pistachios. The same is likely true for other foods, especially those high in fiber. When food is rich in fiber, it can block the absorption of fat from foods. So, the calorie value of a food, as measured, may not be consistent with the calories your body can actually use.
This is just one flaw in the calorie counting model. For one, the calorie model is oversimplified. Your body is a complex machine. A calorimeter measures the energy in food by burning it and measuring how much oxygen and carbon dioxide it produces – but your body extracts energy in many small steps and there’s inefficiency built into the system, meaning the amount that your body actually harnesses varies with the food and the individual eating that food.
In addition, foods themselves have inefficiency build into them. Some foods have higher metabolic efficiency, meaning your body doesn’t have to work as hard to extract the calories from that food. An example would be refined carbs, sugar, and foods low in fiber. Studies show that a meal of processed foods doesn’t force the body to work as hard, measured by an increase in thermogenesis, like a meal of whole, unprocessed foods. Other foods have low metabolic efficiency. This means your body has to expend a lot of energy to get the full calories from that food. Examples would be high-fiber fruits and vegetables.
Calorie Counting: Are All Calories Really Created Equal?
You’ve heard the phrase, “a calorie is a calorie,” but studies suggest that the type of calorie you take in can impact how hard your body has to work to extract that calorie. So, all calories are NOT created equal once they enter your body. Plus, the type of calories you take in impacts insulin, appetite hormones, and other hormones that affect energy balance. Processed carbohydrates and sugar trigger the release of more insulin, thereby making it more likely that the calories you’re taking in will be stored as fat.
In one study, rats ate one of two diets, either a diet heavy on high-glycemic carbs or a low-glycemic diet. High-glycemic foods are ones that cause a rapid rise in blood sugar and insulin. As expected, the rats on the high-glycemic diet had a higher insulin level. They also showed a bump up in enzymes that increase fat storage. What’s more, even when they restricted the calories of the mice on the high-glycemic diet, they still put on body fat. So, calorie quality counts. Eating 200 calories of broccoli has a different impact on fat storage and on metabolic health than a 200-calorie doughnut. Plus, one is almost devoid of nutritional value and the other is rich in nutrients.
Calorie Counting: Are Calories Irrelevant?
Calories still matter. You can make healthy food choices and if you eat huge portions of these foods, you can still gain weight. However, it’s not easy to eat enough of some foods to gain weight. For example, you’d have to eat a ton of non-starchy vegetables to gain weight, assuming you don’t load them up with a heavy sauce. But it’s better to focus on diet quality than counting every calorie that goes into your mouth. Taking that approach is unlikely to be sustainable. If you make the mainstay of your diet unprocessed foods and make sure you’re eating lots of naturally fiber-rich foods and lean protein, the calories will often take care of themselves. When you eat such a diet, your blood sugar is more stable and you’re less likely to have cravings for sugar or processed foods. On the other hand, don’t think you can eat unlimited quantities of calorie-dense foods, even if they are healthy. Calories aren’t irrelevant either.
The Bottom Line
Eat for health, eat what is real, and consume what you eat mindfully. Counting every calorie creates unnecessary stress that can actually cause you to overeat. Most importantly, remember that most people regain the weight they lost through calorie restrictive dieting. You’ll be more likely to maintain any weight that you lose if the approach you’re taking is sustainable.
Live Science. “The Great Calorie Debate”
Socratic.org. “How can a calorimeter measure energy?”
Live Science. “It’s OK to Go a Little Nuts: Some May Have Fewer Calories Than Thought”
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