Allegedly “negative calorie food” identifies certain foods that use up more calories in digestion, absorption and metabolism that they contain in the first place. In other words, calories from these foods are so hard for the body to breakdown and process, that their thermic effects are greater than their calorie values. This in turn could cause a calorie deficit, giving these foods a tremendous fat-burning advantage.
If this assumption was true, eating these foods will cause weight-loss. The problem is that it’s not true. The calories your body burns in the digestive cycle are minuscule compared with the calories in the food itself1.
Except for water, all foods contain some energy. They include an amount of carbohydrate, protein or fat (alone or in varying amounts). All these macronutrients are energy sources, thus all food contains energy (i.e., calories).
The only valid example of negative calorie is when you drink ice-cold water. Water has no calories, but it takes some heat to warm it to body temperature. However, the energy expenditure is so low that drinking ice-cold cannot be considered as an efficient weight-loss method2 .
To give you an idea, even if you drink ten 8-oz glasses of ice-cold water throughout the day you’ll burn about 80 calories. Not bad, but not much. Plus drinking 10 tall glasses of ice-cold water is quite a lot of water and ice-cold water is not always comfortable to drink.
Though scientific evidence indicates that “negative calorie food” is more fiction than fact, there’s a whole diet based on this concept: "Foods That Cause You to Lose Weight: The Negative Calorie Effect “More than 100 negative calorie foods requiring your body to BURN more calories than the actual calorie content of the food itself.” According to this diet you are supposed to “eat all you want of more than 100 negative calorie food, lose weight and feel great.”
The magic foods are the usual suspects. Low-calorie, high nutritional value veggies (and some fruits), such as: celery, cabbage, broccoli, grapefruit, lemon, lime, etc.
However, these foods have nothing to do with a supposed calorie deficit. Take for instance a celery rib. It has about 6 calories. Its thermic effect (i.e., the amount of energy used by the body to digest it) is roughly 0.5 calories; thus leaving a whole 5.5 calories to burn. As per Julie Upton words “In reality, ‘negative calorie foods’ are nothing more than a wishful thinking.3”
If you’re interested in the topic of calories, I urge you to read “Why Calories Count: From Science to Politics (California Studies in Food and Culture)” which explains in clear and accessible language what calories are and how they work, biologically (and politically).
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Oh you better believe it drives me NUTS when people say, "oh XXX has negative calories so I can eat a lot of it" or something along those lines. I want to smack them so hard they wind up in the nutrition class they FAILED in high school. LOL!
ReplyDeletelol! Talking about fitness myths...
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