Negative calorie foods are an intriguing concept: you eat them and they burn more calories than they contain. Here is why they don’t work and can still help you lose weight.
The Concept Of Negative Calorie Foods
These days you find whole lists of supposed “negative calorie foods” on the internet, mentioning anything from apples to strawberries and tomatoes.
The most popular example of a negative calorie food is celery. Its stalks contain high amounts of fiber, are hard to chew and have only very few calories – a 2.2 oz stalk has only 9 kcal.
The reasoning of negative calorie food fans goes as follows: as celery has so much fiber and is hard to digest, the process of digestion costs the body more than those 9 kcal.
But when labs calculate the caloric contents of a food, they already take the energy the body uses for digesting it into account. They call it the “thermal effect of food” (TEF) and you can’t substract it twice.
Still, Negative Calorie Foods Are Useful
Although these foods don’t do what they are advertised with, they can still help you lose weight.
Negative calorie food lists usually contain vegetables and fruits. These are high in volume, but low in caloric content. By switching to these foods, you don’t burn more than they contain, but they may have a lot fewer calories than what you used to eat.
A 2.2 oz stalk of celery has those 9 kcal, a 2.2 oz chocolate bar has around 300. If you manage to eat ten celery stalks you consume approximately 90 kcal. Eat ten chocolate bars and it’s 3,000.
Here is my video discussing the negative calorie foods concept: