What are negative calorie foods?


A transcript follows


Your body gets energy from the food you eat by digesting it, but this is an aspect that many ignore, it needs energy to do this; energy, which is used mainly for chewing, then for the production of stomach acids and various digestive enzymes, for the movement of food during digestion throughout the intestine, and finally also at a more microscopic level, when the biochemical mechanisms necessary to convert carbohydrates, proteins and fats into energy are activated, which the body can use.

All this costs something.

Wouldn’t it be amazing if there were foods so low in calories that they require more energy to digest than they contain?

And these dishes are…

fantasy, dreams, part of the same category as magic diet pills and running unicorns: pure imaginary dreaming.

But it may still be interesting to make some further considerations.

Diet-induced thermogenesis

Diet-induced thermogenesis is the scientific name for a metabolic process, yes, very real, basic digestion, which can also be measured experimentally by observing increased oxygen consumption and greater heat dissipation, which is sufficient to increase body volume. temperature.

Consider that it is so significant that it represents about 10% of your caloric intake, which means that of all the calories you take in with food, about 1 in 10 is used to extract the remaining 9.

Then, as always, it gets more complicated because different macronutrients require different costs and more specifically:

  • protein is particularly difficult, requiring more than 20% of calories supplied,
  • carbohydrates and fats significantly less, for fats much less, between 3 and 4%.

but in the context of a balanced diet built according to the guidelines, the total of 10% is a rough approximation that is not too far from the truth.

Foods with negative calories

Among the foods that are most often cited as examples when talking about foods with negative calories, i.e. foods capable of requiring energy consumption higher than that released, naturally include vegetables such as celery, cucumbers, green leafy vegetables and sometimes some fruits such as is grapefruit and pineapple, perhaps due to the content of enzymes capable of acting on proteins, but this is an even more paradoxical and fairy-tale interpretation if we are talking about calories.

And why can’t there be a food that is so low in calories that it has a negative impact and therefore results in weight loss just by being consumed?

Take for example cucumbers, among the least caloric vegetables, providing only 16 calories per 100 g… not enough, right? However, they cannot be negative, because if we simplify it a little, if we say that to get 9 calories from food we consume on average 1, even exceeding means that 100 g of cucumber will cost us 2 calories and still give us 14 calories.

Even from a mathematical point of view, it can only be this way once we have defined the thermal effect of food in percentages… because a percentage of 10% of any amount can never be greater than this same amount…

Despite this, we still have great reasons to eat a lot of vegetables, perhaps at the beginning of the meal… In addition to being an explosion of vitamins and antioxidants, it also helps us not to overdo it later, with more caloric and energy-dense foods. This is a real effect with real benefits.

But what if we could find foods that are completely calorie-free instead? In that case, even ignoring the fact that consumption would be negligible, if you think you need to burn about 7000 calories to lose a pound, wouldn’t that technically be a negative calorie meal?

In this sense, there are at least 3 interesting examples, let’s start with the most striking one, water.


Water actually has zero calories, but even from a simple intuitive point of view, the fact that one brings the bottle to one’s mouth, swallows, and manages absorption has a metabolic cost, albeit little more than negligible.

And actually we have to admit that drinking water makes you lose weight, precisely in the sense of eating with negative calories, especially if we drink it cold and thus make the stomach produce heat to bring it to body temperature… they proved it experimentally. In fact, it was also calculated: drinking 2 liters of water a day would increase energy expenditure by about 90 calories… not bad, right?

Unfortunately, subsequent studies, and perhaps a little more accurate, failed to confirm this result… My opinion, as far as I can count, is that there may indeed be some energy cost in water consumption, but given that drink more or less all 1-2 L of water per day, the advantage of drinking much more for weight loss purposes would not have significant effects, also justified by the fact that water absorption at the intestinal level occurs mainly passively, thus including subsequent distribution and elimination.

Even in this case, however, it can be useful to use the effect of mass and volume to increase the feeling of satiety during and between meals, if you never overdo it, I remind you that drinking even excessive amounts of water can lead to real intoxication, especially due to excessive dilution of sodium.

Similar conclusions can be reached in relation to tea and coffee, whose thermogenic effect caused by caffeine is practically negligible, while their health benefits are anything but negligible due to the antioxidants they contain… although we have to be satisfied that we are seen demonstrated on paper in epidemiologic studies rather than on a domestic scale.


Another curious example is associated with chewing gum… if you think about it, it actually forces you to do the continuous muscle work associated with chewing, but with essentially zero calorie intake when you opt for sugar-free preparations… the problem is that your the body is pretty well optimized for chewing… it’s estimated that you can burn about 11 calories per hour… not to mention that no gum actually has zero calories in it, reducing the actual benefit even more.


Shiritake noodles

Shutterstock/Ingrid Balaban

Finally, we present the so-called calorie-free spaghetti, shirataki, prepared from konjac, a plant native to Asia and particularly rich in glucomannan, an indigestible fiber; one of the most notable aspects of shirataki is their very low calorie content, generally between 10 and 30 calories per 100g, compared to around 350 for traditional spaghetti.

These spaghetti, noodles or grains, depending on the preparation, have a translucent, gelatinous consistency that may take some getting used to at first before you appreciate or at least tolerate it. Although they can be tasty, especially when accompanied by a vegetable sauce, I personally recommend them only occasionally, since their lack of micronutrients such as vitamins and mineral salts requires special attention to the nutritional balance of the diet.


So the concept of negative calorie foods is, at least from a practical point of view, more of a myth than a scientific reality, but that shouldn’t distract you from the immense and indisputable benefits associated with regular consumption of vegetables, an irreplaceable source of nutrients, fiber and antioxidants, the real silent protagonists of a diet built with the goal of healthy longevity.

And vegetables, like fruits, not only provide a wide range of essential vitamins and minerals, but also contribute to an increased feeling of satiety with a lower caloric intake. This can help not only in weight control, but also in reducing the risk of chronic diseases.

As always, rather than looking for quick or miraculous solutions, we need to embrace and indeed celebrate, embrace the perhaps seemingly quieter but definitely more solid benefits of a balanced, varied and rich plant-based diet.

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