I’ve heard about this thing so many times. How is it possible to eat something, but still burn calories?
In: Biology
Your body burns calories when you eat something. If it is negative calories that means you body is burning more calories to digest the food than the amount of calories you get from the food. The only food I have ever heard that is like this was celery, but I think that was just a myth, I don’t think there are any foods out there that contain fewer calories than it takes to digest them. I could be wrong though.
Ingesting things requires energy. Your jaw burns energy to chew, your saliva glands burn energy to produce saliva, your throat burns energy to swallow, your stomach burns energy to secrete acid and enzymes, etc.
If you ingest something completely devoid of useful energy (say, water, or pure cellulose), you’ll expend calories ingesting it and therefore will be at ‘negative calories’… but it really doesn’t take much energy to swallow things.
There’s no food that contains useful energy that requires more calories to process than you get out of it, though. Digestion is very efficient. You may have heard celery has “negative calories”, but that’s a myth. Pretty much the only thing you’re likely to regularly ingest that expends calories is cold water, because your body has to warm it up to body temperature after you drink it. But you’ll suffer water intoxication well before you expend any serious amount of energy doing that.
The theory is “your body burns up more calories to digest this food, than it is able to extract from the food”.
In reality it doesn’t work that way. It was a joke originally made by someone intentionally mixing up two different definitions of “calorie”. “Negative calorie foods” do not exist.
It isn’t really a thing. At best, a food will have 0 cal. However, some foods require a lot of effort to eat AND have very few calories, and so your net calorie intake is negative. For example, if a baby carrot has around 4 calories, and you burn through 8 calories chewing it, you net -4 calories. At least, that’s the idea. I’m unconvinced.
“Negative calories” is a term that describes foods that supposedly require more energy to digest than the calories they provide. The idea is that eating these foods could help with weight loss because your body burns more calories digesting them than the foods themselves contain.
Here’s an easy-to-understand explanation:
1. All foods contain calories, which are units of energy. When you eat, your body uses these calories for various functions.
2. Your body uses energy (calories) to digest food. This process is called the thermic effect of food (TEF).
3. Some foods, like celery and certain leafy greens, are low in calories and high in fiber and water. The theory is that the energy required to digest these foods might be equal to or more than the calories they provide.
Imagine a piece of celery has 10 calories. If your body uses 10 calories to digest it, you break even. If it uses more than 10 calories, you might end up burning extra calories.
In reality, the concept of “negative calorie foods” is mostly a myth. While some foods have very low calories and can be part of a healthy diet, the energy required to digest them is usually not enough to create a significant calorie deficit.
Even at rest, a body needs energy for all it does. This includes breathing, sending blood through the body, keeping hormone levels even, and growing and repairing cells. The number of calories a body at rest uses to do these things is known as basal metabolic rate, also called basal metabolism.
Basal metalbolic rate can vary from person to person but is essentially the calories burned by the body by just living. So to simplify, if weight loss or gain is just calories in vs. calories out if all you eat in a day is a meal that’s 400 cals but your BMR burns 1200 cals, you would be in a caloric deficit of 800 cals that day or negative 800 calories.
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