The Final Take on Negative-Calorie Foods
Negative-calorie foods – the killer diet trend that’s supposed to have everyone losing weight in droves. Proponents of these foods claim that the body uses more calories to digest the foods than they supply. The idea is pretty solid when you take some of the lowest-calorie foods into consideration, but the metabolism may not be as strong as you think. Can a food actually cause a negative-calorie balance? And, do we know precisely how many calories it takes to digest certain foods?
Let’s take a look, first, at what a calorie really is.
What is a Calorie?
A calorie is a unit of measure. Specifically, it is the amount of energy it takes to increase a kilogram of water by up to one degree Celsius. This may appear to have nothing to do with food but rest assured foods contain calories, and our bodies need those calories to function.
Calories were first defined in the late 1800s. The first term to be used related to a calorie was joule. One calorie equals about 4.2 joules. Today, the term calorie has taken the throne, and few people even know what a joule is.
Believe it or not – there are two types of calories. One is a calorie and the other a kilocalorie. The calorie is a smaller unit than the one we read on the back of nutrition labels. It takes 1000 calories to make up a single kilocalorie. So, when a serving 10 calories, it actually has 10 kilocalories and 10000 calories.
For the sake of negative-calorie foods, we’ll stick with the traditional term calories for the units in food.
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How are Calories in Foods Determined?
Now, the calories in each food don’t just magically appear when they are picked, prepped, or processed. A machine called a calorimeter was once used to determine the calories in food. “Food was placed in a sealed container surrounded by water – an apparatus known as a bomb calorimeter. The food was completely burned and the resulting rise in water temperature measured.” This measurement was used to determine the total calories in the food.
Today, thanks to information provided by the bomb calorimeter, we know that proteins supply about 4 calories, carbohydrates about 4 calories, fats about 9 calories, and alcohol about 7 calories – per gram. When food is labeled, these figures are used to calculate the total calories.
What Do Calories Have to Do With Weight Loss?
Before getting any deeper into the negative-calorie food debate, let’s take a look at what science has to say about the impact of calories on weight loss.
According to research from 2017 in Global Health Action, treating obesity using a calorie imbalance, such as taking in fewer calories than you burn, “may not be sufficient to manage and reverse obesity.” So, even if there are negative-calorie foods, will those foods be able to actually to help you lose weight?
Also, in 2017, research in Perspectives on Psychological Science shared research with the same results. This time around, not only were calories found to have little impact on overall weight loss, but there’s also a possible connection to weight gain. The study revealed, “a reduction in energy intake is counteracted by mechanisms that reduce metabolic rate and increase calorie intake, ensuring the regaining of lost weight.”
The Negative-Calorie Food Debate
A simple search for ‘negative-calorie food’ will return 10s of millions of results. There is no lack of information on the foods that magically cost more calories to digest than they supply. With this theory in mind, eating only negative-calorie foods would result in extreme weight-loss, which could cause severe side effects – over time.
That’s only one part of the debate. There’s also the fact that everyone has a different metabolism, and foods cost a different number of calories to digest for each person. What is a negative-calorie food, loosely used, for one person may not be the same for another.
Research from 2014 published in Health Scope showed that, based on a review of all available studies, the negative-calorie diet was no more effective than a traditional low-calorie diet. Essentially, the two are the same as both support eating more low-calorie fruits and vegetables.
Another bit of research puts the brakes on the negative-calorie debate, or so it seems. Based on information from the Academy of Nutrition and Dietetics, only about 10% of total calorie intake is used for the digestive process. There is a slight thermic effect of food that comes with every food eaten, so that’s taken out of the equation. So, if you eat 15 calories of celery, you will burn about 1.5 calories digesting it. That’s far from the total 15 calories you consumed.
Types of Negative Calorie Diets
There are various types of diets that, based on the rules of the diet, could be considered to be based on negative-calorie foods. Before jumping into any of these diets, let’s take a look at the most common negative-calorie foods. All negative-calorie foods are in the fruit and vegetable categories. This is not an all-inclusive list, but it does give a good look into the types of foods that are not supposed to hurt your calorie count.
List of Negative-Calorie Foods
- Sprouting Broccoli
Now, let’s take a look at how these foods fit into diets that typically support the low-calorie options.
Raw Food Diet: A raw food diet exists when a person consumes only foods heated to no hotter than 115 degrees. Most foods are consumed raw, thus the name. With raw food diets usually comes a vegetarian or vegan menu. Most animal products need to be cooked to a higher temperature than 115 degrees for safety.
You can bet that many of the foods listed above are consumed by people on the raw food diet. However, taking in only raw foods makes it difficult to meet nutrition requirements for overall health. So, you need more to your diet than negative-calorie foods.
Very Low-Calorie Diet: A very-low-calorie diet is one that supplies fewer than 800 to 1000 calories. The menu is typically suggested by a healthcare professional as part of medical weight loss. Sometimes meal replacements are used for protein needs, but many of the negative-cal foods are also allowed and recommended. The foods aren’t recommended because they are proven to burn more calories than they supply – they are included because of the strong nutrition profiles.
Liquid Diet: A liquid diet is also often prescribed by a healthcare professional. In most cases, the menu consists of meal replacement or protein shakes. Some people find a liquid diet more natural to adopt after having weight-loss surgery. Fruits and vegetables can be juiced and consumed in natural form, which also, in this case, is encouraged because of the nutrition provided – not because the foods burn calories.
hCG Diet: The final diet that relies heavily on foods, commonly referred to as negative calorie, is the hCG diet. First and foremost, there is no research to prove hCG promotes weight loss. And, hCG is a prescription medication that’s not available in supplement form. Now, on to the diet. You are allowed no more than 500 calories a day, and the calories are often consumed in fruit and vegetable forms. The hCG diet is highly restrictive, and the fruits and vegetables are often the only sources of nutrition.
The diets mentioned above are not considered healthy or long-term solutions for weight loss. When you try a program like Noom, it takes just 10 minutes a day to learn how to eat, how to move, and how to feel better about yourself.
Negative-Calorie Food List and Nutrition
Jumping back a little bit, let’s take a closer look at the foods that are supposed to be negative calorie and check out the calorie totals for each. Here you’ll find the total calories in one serving of each food, the 10% of calories it takes to digest the food, and the net calories supplied to the body.
- Apple: 57cals/cup – 6cals = 51cals
- Cucumber: 8cals/cup – 1cal = 7cals
- Carrot: 53cals/cup – 5cals = 48cals
- Sprouting Broccoli: 31cals/cup – 3cals = 28cals
- Celery: 18cals/cup – 2cals = 16cals
- Lettuce: 10cals/cup – 1cal = 9cals
- Grapefruit: 52cals/1/2 fruit – 5 cals = 47cals
- Spinach: 7cals/cup – 1cal = 6cals
- Tomato: 27cals/cup – 3cals = 24cals
- Watermelon: 46cals/cup – 5cals = 41cals
- Kale: 34cals/cup – 3cals = 31cals
- Strawberries: 50cals/cup – 5cals = 45cals
Based on the idea that you only burn 10% of total calories during digestion, none of the foods listed would actually cause a negative-calorie effect.
How Many Calories Does it Take to Digest Food?
Thermic Effect of Food
The thermic effect of food is the total number of calories it takes to digest said food. The percentage varies among people, body weight, health, and even specific food. What’s interesting about negative-calorie foods is that most are carbohydrate heavy. It takes a shorter time to digest carbohydrates than it does protein and fat, which is why the latter of the two help you feel fuller longer after you eat. Eating carbohydrate-heavy foods may help you feel full right now, but without some protein and fat, the effect won’t last. Eventually, you could be eating more calories in fruits and vegetables than you would if you didn’t focus on negative-calorie foods.
Factors that affect the thermic effect of food include:
- Macronutrients – protein, carbs, fat
- Calories in foods you eat
- Negative-Calorie Foods and Weight Loss
Research doesn’t say much for the negative-calorie food diet. It appears that eating a diet based on these foods is no more effective than a low-calorie diet. Specifically, when comparing the two diets, “Contrary to expectations, both weight-loss diets were equally efficacious,” according to the Turkish Journal of Medical Sciences.
There’s also a problem with underestimating the total number of calories in “healthy” foods. When groups of people were asked to decide which of two foods contained fewer calories, they often chose the negative-calorie foods. However, both foods contained the same amount of calories. Thus, people who believe healthy foods contain fewer calories may eat more and be consuming more calories than they would have with more traditional meals, says research in PLoS One.
Can You Eat Unlimited Vegetables and Lose Weight?
No, you cannot eat unlimited vegetables and lose weight. Assuming that you’re consuming some other foods in your diet, there are other calorie sources to take into consideration. Following a diet that’s made up of only negative-calorie foods is unsafe and unhealthy. Not only will the diet supply too few calories, but essential macronutrients, vitamins, and minerals are missing from many fruits and vegetables. You simply won’t get what you need to stay healthy, and severe side effects could occur.
The Centers for Disease Control and Prevention (CDC) does into great detail on how to add fruits and vegetables to your diet to get the most out of these superfoods, and nothing is mentioned about the foods causing a negative calorie effect.
Can You Make a Negative-Calorie Meal?
An interesting topic that’s come up as of late is the concept of the negative-calorie meal. Imagine combining very low-calorie foods with food-based metabolism boosters. Could that, in theory, help you burn more calories? Believe it or not, the answer is yes.
While there are no negative-calorie foods, some foods do help increase metabolism, so when partnered with these low-cal foods, you could burn more calories.
For instance, steaming broccoli adds no additional calories, so one serving is about 30cals. Top that broccoli with some chili peppers or calorie-free hot sauce, and things could get good from there.
Chili peppers have been shown to increase metabolism through the body’s reaction to heat. Thus, if you eat spicy peppers with your super low-cal food (negative-calorie food), you will burn more calories than if you didn’t.
Weight-Loss Programs and Negative Calorie Foods
The proponents of negative-calorie or zero-calorie foods aren’t limited to people on the internet or those trying to sell some programs. There are at least two major weight-loss programs that promote, or have promoted, the idea of zero-calorie foods.
Weight Watchers (WW): In most versions of WW, there has been some sort of 0-point food list. These foods can be consumed in the amount you like as long as you don’t overeat, and they don’t count toward your point total. Points are equivalent to calorie intake with the WW program. There are no foods with no calories, so all foods count.
Nutrisystem – Nutrisystem is another of the programs that support zero-calorie foods. The Numi app, which is the partner app to the Nutrisystem food program, doesn’t subtract the calories consumed as part of a predetermined list of foods – many of which are considered negative-calorie foods. We must say again: all foods have calories and all calories on a plan where calories count should be counted.
Sugar Substitutes and Weight Loss
One final topic to touch on in negative-calorie foods is the sugar substitute. You can buy everything from baked cookies to sodas or tea that contains some form of sugar substitute. The alternatives claim to have zero calories – so you get the sweetness of sugar without the simple carbs.
The problem with sugar substitutes is that science is up in the air about safety and the effect on appetite.
In one study published in the Yale Journal of Biology and Medicine shares that in some people who choose products with artificial sweeteners, weight gain occurs. There appears to be some connection between the sweeteners and an increase in appetite though the effect does not occur in everyone.
Another study, this time in Current Gastroenterology Reports says, “Although artificial sweeteners were developed as a sugar substitute to help reduce insulin resistance and obesity, data in both animal models and humans suggest that the effects of artificial sweeteners may contribute to metabolic syndrome and the obesity epidemic.”
The journal Obesity Silver Spring brings up the possibility that consuming non-nutritive (artificial) sweeteners can actually be harmful to metabolism – as found in animal studies. In human studies, the effect on obesity was found to be marginal – but significant.
Final Take on Negative-Calorie Foods
There are no negative-calorie foods. Some foods contain very few calories and a lot of water, so they fill you up, and you eat fewer calories from protein and carbs. There is some traction to the idea of adding fat-burning foods like chili peppers to the low-calorie, neg-cal foods to increase calorie burn. Still, even considering that, the vegetables and fruits often called negative-calorie foods supply calories. Only about 10% of total calories are burned indigestion.
You don’t have to count calories to lose weight. You can adopt healthy lifestyle changes that help guide you through the process of picking up great habits for exceptional results. With Noom, a clinically-proven weight-loss program, you take 10 minutes a day to change your entire life, and you don’t have to worry about negative-calories.
Negative-Calorie Foods QA
What are negative-calorie foods?
There are no negative-calorie foods. Fruits and vegetables on the negative-calorie food list often contain fiber, lots of water, and fewer than 100 calories per serving. When you eat foods on the negative-calorie food list, your body burns about 10% of the total calories to digest and process the food. All bodies and foods are different so the total number of calories burned can range up to 15%, but it is never 100%
Do negative calorie foods exist?
No, negative-calorie foods do not exist. All foods supply calories and no foods cost more calories to digest than they supply.
What foods burn more calories than they contain?
No foods burn more calories than they contain. Only about 10% of a food’s calories are used up during digestion. There are foods that help improve metabolism, like chili peppers and black pepper, which may have a marginal effect on calories.
What happens if you only eat zero-calorie foods?
If you only eat zero-calorie foods, you will eventually suffer from malnutrition and starvation. There are no zero-calorie foods, so there will be some calorie intake, even if you are sticking with a negative-calorie food list. However, the nutrition needed to perform basic functions is not available strictly from negative or zero-calorie foods.
What can you snack on that has no calories?
Water, unsweetened tea, and black coffee are all zero-calorie snacks. Simply freeze the water or tea with lemon or lime juice, or the coffee black with a toothpick. Once frozen, take out and enjoy as a popsicle. If you’re comfortable using non-nutritive sweeteners, you can add flavor or sweetness to the tea, water, and coffee before freezing.
What drinks have no calories?
Water, unsweetened tea, black coffee, herbal tea, and most diet sodas contain no calories. There are a few diet sodas on the market that contain between 5 and 15 calories per serving.
What is the most fat-burning food?
There are no foods that actually burn fat, but there are elements in food that have been shown to help increase or support a healthy metabolism.
Coffee and tea contain caffeine and other chemicals that can promote a healthy metabolism. This has been associated with weight loss.
Another good addition to the list of fat-burning foods is chili pepper or hot pepper. Peppers contain capsaicin, which can increase metabolism and decrease appetite. Plus, eating spicy foods slows down the rate at which you eat, so your stomach has more time to signal when you’re full to your brain.
Summer Banks has researched over 5000 weight-loss programs, pills, shakes and diet plans. Previously, she managed 15 supplement brands, worked with professionals in the weight loss industry and completed coursework in nutrition at Stanford University.