Some foods are believed to have “negative calories” – meaning it takes more calories to digest them than they contain. The theory is that eating these foods can help promote weight loss by burning more calories during digestion than the foods provide. However, the concept of negative calories is controversial among health experts. While some foods do require more energy to digest than they contain, the actual calorie difference is often negligible. Regardless, foods touted as negative calorie can be part of a healthy diet due to their low calorie density and high nutrient content.
What are negative calorie foods?
Negative calorie foods are foods that supposedly require more energy to digest than they provide in calories. For example, if a food contains 50 calories but requires 150 calories to digest, it would have a “negative” calorie value of -100 calories. The theory behind negative calories is that by eating these foods, you end up burning more calories than consuming, leading to weight loss. Some examples of foods commonly believed to have negative calories include:
- Fruits and vegetables – celery, apples, berries, citrus fruits, leafy greens
- High fiber foods – oats, beans, legumes
- High protein foods – lean meats, fish, egg whites
- Low calorie dense foods – broth-based soups
Proponents of negative calorie foods claim that by eating plenty of these foods while restricting higher calorie options, it can spur weight loss. However, it’s debatable if these foods truly have a negative calorie effect.
Do negative calorie foods really exist?
Despite the popularity of the negative calorie food theory, most nutrition experts agree that no foods actually have a negative net calorie effect. This is because:
- The body does not burn nearly as many calories digesting food as claimed.
- Calories from carbohydrates, protein and fat require similar energy to digest and absorb.
- The thermic effect of food (TEF) – or calories burned digesting food – is only 10-15% of total calories.
For example, a raw celery stalk may contain only 6 calories. But the thermic effect of food for celery is estimated at around 8%. So eating a stalk of celery would only burn an extra 0.5 calories, not enough to produce a negative calorie effect.
In reality, the calorie differences between most low and high calorie foods are not significant enough to produce negative calorie values.
Why are they believed to have negative calories?
There are several reasons why certain foods are mistakenly believed to have a negative calorie effect:
- Low calorie density – Foods like fruits, vegetables and lean proteins are very low in calories per gram. So you can eat a large portion of these foods for very few calories.
- High fiber and protein – Fiber and protein rich foods take more energy to break down. So they have a slightly higher thermic effect than fats or carbs.
- Water content – Foods with high water content like fruits, veggies and soups require energy to heat up and metabolize the water.
- Nutrient deficiencies – Eating low calorie foods may help correct nutrient deficiencies, allowing the body to function more efficiently.
While these factors don’t produce a significant negative calorie effect, they do help these foods promote weight loss in a healthy, sustainable way.
Do negative calorie foods help with weight loss?
Despite the questionable negative calorie theory, foods often listed as negative calorie can be beneficial for weight loss. This is because:
- They are low energy dense foods that fill you up without adding calories.
- They provide essential vitamins, minerals and phytonutrients.
- High fiber foods slow digestion and control hunger and appetite.
- Protein requires more energy to metabolize than carbs or fat.
By replacing high calorie foods with low calorie dense fruits, veggies and lean proteins, you reduce overall calorie intake which promotes weight loss over time. So while not scientifically negative calorie, these foods can help support weight loss.
The top 10 negative calorie foods
Here are 10 of the top foods often promoted as negative calorie:
1. Celery
- Calories: 6kcal per stalk
- High water and fiber content
- Crunchy texture promotes chewing and digestion
- Provides vitamin K, potassium, folate
2. Broccoli
- Calories: 31kcal per cup
- High in fiber, vitamin C, vitamin K
- Phytonutrients may help prevent cancer
- Crunchy texture requires chewing
3. Carrots
- Calories: 52kcal per cup
- Beta-carotene is converted to vitamin A
- High water and fiber content
- Sweet flavor curbs cravings
4. Strawberries
- Calories: 32kcal per cup
- High water content makes them low calorie
- Fiber fills you up and aids digestion
- Rich in vitamin C and manganese
5. Apples
- Calories: 95kcal per apple
- Pectin fiber nourishes good bacteria
- Quercetin acts as antioxidant
- Satisfying crunch curbs appetite
6. Grapefruit
- Calories: 60kcal per half grapefruit
- High water content is filling but low calorie
- Phytonutrients may prevent insulin resistance
- Tart flavor satisfies sweet craving
7. Cauliflower
- Calories: 25kcal per cup
- Low starch prevents blood sugar spikes
- Phytonutrients may help fight cancer
- Crunchy florets promote chewing
8. Asparagus
- Calories: 20kcal per cup
- Diuretic effect flushes excess water
- Prebiotic fiber nourishes gut bacteria
- Nutrients like folate, potassium, thiamine
9. Tomatoes
- Calories: 25kcal per tomato
- High water content fills stomach
- Lycopene antioxidant fights free radicals
- Low glycemic index prevents insulin spike
10. Zucchini
- Calories: 18kcal per cup
- Mild flavor allows versatility in recipes
- Provides vitamin C, riboflavin
- Low starch and high water is filling
Healthy negative calorie diet meal plan
Eating more of these low calorie foods can help you lose weight. Here is a sample high negative calorie meal plan:
Breakfast
- Oatmeal made with water or unsweetened almond milk
- 1 apple, sliced
- 1 cup berries
Lunch
- Tuna salad made with 2 hardboiled eggs, lettuce, tomato
- 1 cup celery sticks
- 1 cup unsweetened iced tea
Dinner
- 3oz grilled chicken breast
- Sauteed zucchini, broccoli, asparagus
- Side salad with lettuce, cucumber, tomato
Snacks
- Sliced bell peppers and hummus
- 1 grapefruit
- Plain greek yogurt with berries
- Baby carrots
This meal plan maximizes high fiber fruits, vegetables and lean proteins while limiting calorie dense foods. Be sure to stay hydrated by drinking water throughout the day.
Cooking and preparing negative calorie foods
The key to enjoying negative calorie foods is learning how to incorporate them into your diet. Here are some tips:
- Eat fruit and veggies raw – Raw fruits and vegetables contain the most nutrients and require the most energy to digest.
- Steam or roast – Cooking methods like steaming, roasting or grilling are lower calorie than frying.
- Freeze berries – Frozen berries make for delicious low calorie snacks or additions to smoothies.
- Flavor with herbs and spices – Boost flavor without calories by using garlic, onions, herbs and spices.
- Try new veggies – Mix up your usual veggie choices by trying zucchini spirals, riced cauliflower or spaghetti squash.
Negative calorie snack ideas
Snacking can be challenging when trying to limit calories. Here are some ideas for healthy, low calorie snacks:
- Berries dipped in dark chocolate
- Apple slices with 1 tbsp peanut butter
- Bell peppers and hummus
- Celery sticks and salsa
- Plain nonfat greek yogurt
- cottage cheese with tomato and cucumber
- Hard boiled egg
- Kale chips
- Frozen grapes
- Roasted chickpeas
Precautions with negative calorie diets
While emphasizing negative calorie foods is healthy for weight loss, there are some precautions to consider:
- May lack adequate calories – Eating only very low calorie foods risks not getting enough calories and nutrients for health.
- Lack of protein – Make sure to still consume enough lean protein for maintaining muscle mass.
- Nutrient deficiencies – Vary your fruit and vegetable choices to ensure you get a wide range of vitamins and minerals.
- Sustainability – An overly restrictive negative calorie diet may be hard to stick to long term.
The bottom line is to use common sense. Focus on whole, minimally processed negative calorie foods as part of a balanced diet to support gradual weight loss.
Frequently asked questions
Are there really negative calorie foods?
No food technically has a negative net calorie value. However, foods like fruits, vegetables and lean proteins require more energy to digest than fats or carbs. So they provide fewer net calories that may assist in weight loss.
Do negative calorie foods boost metabolism?
They can slightly increase metabolism since protein-rich foods increase the thermic effect of food (TEF) and require more energy to break down. High fiber foods also require more digestion. But the effect is often marginal.
Can you survive only on negative calorie foods?
Strictly limiting intake to only the lowest calorie foods is not sustainable or healthy long term. You may lose weight rapidly but would become deficient in calories, protein, healthy fats and other nutrients.
How much weight can you lose eating negative calorie foods?
There are no solid studies on solely eating negative calorie foods. But emphasizing them to reduce overall calorie intake could promote gradual weight loss of 1-2 pounds per week.
Which food has the most negative calories?
Celery is typically considered the classic negative calorie food. One stalk contains only 6-7 calories but requires around 8 calories to digest. Other top options are broccoli, carrots, fruits and leafy greens.
The bottom line
While no foods truly contain negative calories, many fruits, veggies and lean proteins require more energy to digest than they provide. By eating more of these low calorie dense foods as part of a healthy diet, you can lose weight and improve health.
