There are a number of healthy eating theories and misconceptions that have been around for quite some time. Among them is the theory of foods with minus or negative calories.
The adherents of the theory argue that there are foods with too little calories, when digested, the body spends more calories than these foods contain. For example, a cup of lettuce contains about 30 kcal, 40-50 kcal is consumed for digestion, that is, the body "burned" 10-20 kcal in the process of digesting food, which is undoubtedly a plus for people losing weight or following a sports diet. This may already seem absurd. It seems that no training is needed, foods with a negative calorie content will be a kind of gym or treadmill, you just need to eat these foods. All types of lettuce, cabbage, tomatoes, cucumbers, some types of citrus fruits and apples, and some other plants are classified as “negative calorie” ones.
Scientists are skeptical about the theory of foods with negative calories, explaining this by the existence of the so-called thermal effect of food (short for TEF). It is ETF that expresses the amount of kcal consumed by the body for digestion. The ETF ratio cannot exceed 100% in any way, but ranges from 3% to 30%. Simply put, for every 100 kcal received, the body spends a maximum of 30 kcal. But even these maximum 30% the body spends on the digestion of protein foods, that is, most often food of animal origin, which does not include salads, cucumbers, and so on.
Indeed, foods with a "negative calorie", like carbohydrate foods, spend only 5-10% on their digestion. For example, with an apple of 50 kcal, the body will receive about 40 kcal. A distant confirmation of the theory can be seen in the content of certain foods of special substances that increase the body's metabolism (for example, synephrine in grapefruit), but this is not a negative calorie value.
So, foods with "negative calorie content" are actually just low-calorie foods, the advantage of which is the presence of fiber and water in the composition, which gives a satiating effect and generally has a beneficial effect on digestion. This is what leads to a decrease in body weight, since the volume of food itself is reduced due to low-calorie vegetables. When calculating the daily diet, such vegetables may not be taken into account at all, since their calorie content is too low to be deposited in fat. Indeed, no one has yet grown fat by eating cucumbers, cabbage or lettuce. Takeaway: Vegetables, especially green vegetables, should be present whenever possible with every meal because of their extreme health benefits, but should not be confused with negative calories.
