The Science Behind Negative Calorie Foods

The Science Behind Negative Calorie Foods

If you're aiming to live a healthier lifestyle, your calorie intake is an essential consideration. It factors into your fat loss, fat gain, lean muscle mass, and even your energy levels, which means keeping track of your calories is critical to your success. However, just because you're eating well, it doesn't mean you can't overeat. That's why just about everyone goes out of their way to find foods that are satiating, nutritional, or just plain tasty that aren't going to break their caloric budget.

If you find yourself in a similar situation, chances are, you've stumbled upon the topic of "negative calorie" foods in the past. But, what does that even mean and are they just too good to be true? Here's what science has to say.


What Does Negative Calorie Mean?

Certain foods have gained massive popularity in recent years among those trying to lose weight because they have gained a reputation of being "negative calorie," meaning that you actually burn calories by consuming them. Obviously, that sounds incredible, which is why most people are rightfully skeptical about the whole idea. How is it even possible that a food burns calories?

Food contains many nutrients that your body needs, and the macronutrients--namely, carbs, fats, and proteins--all contain calories. However, your body also has to expend calories (in the form of energy) in order to process the food that you eat. How much energy you have to expend depends on the type of food it's processing, as some are easier to process than others.

So, the concept behind negative calorie foods is that your body spends more calories processing them than they actually contain. This means you could theoretically lose weight by making negative calorie foods part of your daily diet, because they are said to burn calories. Typically, fruits and veggies that have a high water content are promoted as negative calorie foods.

Examples of Negative Calorie Foods:

Here are foods that are often marketed as negative calorie:

  • Celery, which has 14 calories per cup
  • Carrots, which have 52 calories per cup
  • Lettuce, which has 5 calories per cup
  • Broccoli, which has 31 calories per cup
  • Grapefruit, which has 69 calories per cup
  • Tomatoes, which has 32 calories per cup
  • Cucumbers, which have 8 calories per cup
  • Watermelon, which has 46 calories per cup
  • Apples, which have 53 calories per cup

These foods definitely contain calories, so the question is: Does your body expend more calories trying to process them?


The Truth Behind Negative Calorie Foods:

While the "negative calorie" foods people talk about are generally extremely low calorie given their volume and, in general, quite healthy for you, there is actually no scientific evidence to support the concept that they require more calories to process than they provide. However, there are some facts that help perpetrate the negative calorie food concept.

For instance, a limited body of research shows that people who chew gum can increase the calories they burn by approximately 11 calories per hour. While it's a lot if you consider how little effort it takes to chew gum for an hour, the number is so minuscule that chewing alone isn't enough to support the negative calorie hypothesis--unless you take an hour to eat a cup of lettuce, in which case you have certainly expended more effort than it's worth.

Generally, your body requires up to 10% of a food's caloric amount from carbs, up to 5% for its calories from fat, and up to 30% from the calories it derives from protein. With very little fat or protein in most "negative calorie" foods, it's unlikely that digesting these foods takes a lot, but there is no specific research on this matter.


What About Calorie-Free Foods?

While negative calorie foods aren't supported by science, there are certainly low and no-calorie foods that you could use as part of a healthy diet. However, it's generally best to think twice before consuming completely zero calorie foods as it generally takes a lot of unhealthy processing to remove the calories, or use of artificial ingredients. Instead, look for healthy, naturally low calorie foods.

Here are some examples that are rich in nutrients but don't contain a lot of calories:

  • Kale contains 7 calories per cup
  • Blueberries contain 84 calories per cup
  • Potatoes contain 58 calories per cup
  • Raspberries contain 64 calories per cup
  • Spinach contains 7 calories per cup

Meanwhile, if you're looking for low-calorie protein sources, consider salmon, chicken breast, plain greek yogurt, whole eggs, or pork tenderloin. In general, aiming to eat more whole (less processed or unprocessed) foods is the ideal way to go for anyone trying to live a healthier lifestyle.

While you may not be able to burn calories with negative calorie foods, you can surely supplement your diet with plenty of healthy options that will help you lose weight anyhow.