The field of nutrition is full of interesting myths, and one of the longest-running ones is the idea of “negative calorie” foods. The premise is straightforward and tempting: celery and apples come to mind taking more energy to digest than they provide which results in a calorie deficit. This is a wildly popular myth among dieters, often keeping people curious about “how many calories in an apple” and hoping the answer to the question reinforces the idea. But is this a real thing or is it just a myth? Let’s evaluate the nutritional facts versus fiction.
The Myth of the “Negative Calorie” Food
The idea of negative calorie foods is based upon the thermic effect of food (TEF). TEF is the energy that the body uses to digest, absorb, and metabolize the nutrients contained in the food you eat. The TEF is very real, and it typically accounts for about 10% of your total daily caloric intake.
The myth states that for certain low-caloric, high-fiber foods, the TEF of those foods could be higher than the caloric density of the food itself. For example, if you said to yourself “how many calories does an apple have”, typically about 80 to 100 calories for a medium size folks advocating for this myth may say the body could use as much as 110 calories to digest that food, resulting in a negative caloric intake. Unfortunately, there is no scientific evidence or data that supports the myth of negative calorie foods.
The Fact: Apples are a Low-Calorie Powerhouse
In reality, there is not a single reputable scientific study that has demonstrated the existence of negative calorie foods. Case in point, even the most fibrous, watery vegetables will not thermic any greater than the caloric value of that food item. The calories you see when you Google, “how many calories in an apple,” is a net energy, not gross, scenario.
So, what is the true energy cost of an apple? Yes, the human body takes energy to digest food. However, the TEF for whole foods, such as an apple, will only be a percentage of the total caloric energy in the food. You might expend 5-10% of the total caloric energy of the apple via digestion. Therefore, if you eat a 95-calorie apple, you might expend 5-10 calories to eat and digest it, leaving you with, or gaining, around 85-90 calories. This is not a negative caloric deficit.
However, this is where we arrive at the true, and perhaps most important, insight. Just because apples are not “negative calorie” foods, doesn’t mean that they are not a great mechanism to use for weight management. This is where the real insight lies and the real value.
Why the Myth Persists: The Real Benefits of Apples
The negative calorie myth is sustained because there is a small amount of legitimacy regarding the applicability of low-energy-dense foods. This is the reason apples can be so advantageous, almost like “a cheat code for being on a diet.”
Low Caloric Density: The primary question involved, in terms of how many calories is an apple, has a very satisfactory answer: not many. For under 100 calories, you’ll have a huge, fulfilling apple, which can likewise complement the other snacks you’re eating, depending on your individual calorie budget, and it can help stave off hunger.
High-Fiber: Apples contain a large amount of dietary fiber, especially a type of fiber known as pectin. Fiber slows the process of digestion which increases feelings of fullness and satiety. Afterward, it might help keep you from overeating later in the day which can assist with a calorie deficit indirectly.
High Water Content: Apples consist of approximately 85% water, which acts to provide volume to your diet without the addition of any calories, thus causing you to feel full in addition to being satiated.
Requires Time Chewing: It eventually takes longer to chew an apple than to drink a smoothie or eat a processed snack, as it is more physical. This allows our body’s signals of feeling full to connect with our brain.
Conclusion
Is the apple actually a mythical food with negative calories? No. However, it is still a nutritional rock-star as well in its own right. When you’re next confronted with the question: how many calories in an apple?, keep in mind that this number is really just one part of the entire nutrients picture.
