Whether or not foods can actually have negative calories is a controversial topic. Proponents of the idea claim that some foods require more calories to digest than they actually provide. However, most experts agree that no foods can truly have negative calories. This article will examine the debate around negative calorie foods and explain why they likely do not exist.
What are negative calorie foods?
The concept of negative calorie foods is based on the idea that digesting and metabolizing certain foods requires more energy than the foods contain. For example, if a food had 100 calories but required 150 calories to digest, it would have a “negative” calorie value of -50 calories. Some examples of foods claimed to be negative calorie include:
- Fruits and vegetables: celery, spinach, grapefruit, apples
- Lean proteins: chicken breast, egg whites, fish
Proponents believe that by consuming these low-calorie foods that require significant energy to digest, you can create a calorie deficit and lose weight. However, nutrition experts disagree that any foods actually have negative calories.
Do foods require more calories to digest than they contain?
The notion that a food could require more energy to digest than it provides goes against the laws of thermodynamics. The energy balance equation states:
Energy in = Energy out
This means the calories contained in food must match the energy required for the body to metabolize and digest it. There cannot be an imbalance where digestion requires MORE energy than the food provides.
While digesting foods does require a small amount of energy, it is not nearly enough to make the foods negative calorie. For example:
- A 100 calorie apple may require 5-10 calories to digest.
- A 50 calorie stalk of celery may take 10-15 calories to digest.
The thermic effect of food (TEF) refers to the energy required for this digestion process. On average, TEF only accounts for about 10% of total energy expenditure. For most foods, the TEF is not even close to making them negative calorie.
What does science say about negative calorie foods?
Despite the popularity of negative calorie food lists, there is no scientific evidence supporting their existence. Nutrition experts and major health organizations point out several flaws with the negative calorie food theory:
- No reputable scientific studies have proven foods can have negative calories.
- The laws of thermodynamics disprove the possibility of negative calorie foods.
- Even very low-calorie foods like celery and spinach provide SOME usable calories and nutrition.
- Most negative calorie lists include fruits and vegetables that are actually high in calories like apples, oranges, carrots, and tomatoes.
Here is what some major health and nutrition organizations have to say on the matter:
| Organization | Position on Negative Calorie Foods |
|---|---|
| Academy of Nutrition and Dietetics | “There are no foods that contain negative calories. Food provides energy which the body uses immediately or stores for future use. No food requires more calories to digest than it provides.” |
| Mayo Clinic | “No food can have negative calories. Period.” |
| Cleveland Clinic | “There are no negative calorie foods. It’s physically impossible for any food to have negative calories.” |
As you can see, major health organizations unanimously agree that foods cannot contain negative calories due to the laws of physics and nutrition science.
The downsides of focusing on negative calorie foods
While fruits, vegetables, and other low-calorie foods can certainly help, the concept of negative calorie foods has some downsides:
- It encourages an unhealthy focus on calories rather than nutrition.
- Low-calorie foods still need portion control to manage weight loss.
- It may promote disordered eating habits like extreme restriction.
- People may ignore calorie counts if they believe a food is “negative calorie.”
Rather than focusing on negative calories, it’s better to have a balanced diet with plenty of nutrient-dense whole foods. Calories still count, even for fruits and vegetables.
The bottom line on negative calorie foods
While some low-calorie foods like celery and spinach may provide minimal calories, no foods actually contain negative calories. The thermic effect of food is not large enough to surpass the calories provided.
At the end of the day, calories still matter. Even when choosing low-calorie fruits and vegetables, portion control is important for weight management. Aim for a balanced diet with a variety of nutritious foods instead of fixating on “negative calories.”