Under normal conditions, the good weather arrives and, with it, the desire to show off our body. But of course, first we would have to eliminate all that we accumulate to get through the cold winter, right? It is time to change our entire pantry with "light" products, very low in fat and sugars.
At least, that’s how many consumers think, who are not aware of a stark reality: there is no evidence that the use of "light" products helps, in the end, to reduce weight . At least not by himself. The question is much more complex than it seems.
There is no evidence to defend the "light"
The only existing secret to reducing weight is one: the caloric deficit . That is, spending more than what we eat. Of course, this question is not that simple, since there are many more values at stake: nutritional quality, basal expenditure and muscle mass, type of diet …
But summarizing a lot, it is clear: if there is more energy than we use, it accumulates as fat and glycogen . From this perspective, a "light" product, with fewer kilocalories per unit, should help us, right? Well not always. That is what the studies on the matter to date reflect.
There is no evidence that "light" products (always reviewed by food groups) help more than others to reduce body weight or obesity. This seems to contradict the reasoning that we launched a few lines ago. If the trick is to reduce kilocalories, why don’t they work?
Why "low-fat and low-sugar" products don’t work
In the first place, the problem is in how the energy of the products is counted. The process to evaluate the caloric intake is the same for all products, using a calorimeter and / or the tables of the Atwater method. This means that counting calories is the same for all foods. But for our body it is not .
The bioavailability of nutrients varies greatly from one food to another, even in what we accompany them with. Sometimes calories are "not worth" the same depending on what we eat. On the other hand, some "light" products do not contain sucrose and free sugars, but they do contain other sweeteners that, although to a lesser extent, also accumulate.

In others, the caloric percentage is removed from fats and replaced by sugars , which more easily pass into our reserves. It also happens that, in some products with non-caloric sweeteners, the production of insulin is encouraged, which accumulates sugars that come from other foods or reactions.
Finally, and most importantly, the reasoning is too simple: we can not only subtract kilocalories from one or another food . The change must be complete, in diet and habits. It is important not to focus only on specific, unique foods, since not only is it not an effective effort, but it could lead to harmful habits.
The curious case of dairy
Let’s start with one of the most accused issues in this "light" food: dairy. There are hundreds of skimmed milks (skimmed, semi-skimmed, special 0% cheeses, "diet" yogurts …). Although we cannot put all these products in the same bag, there is a general tonic in dairy: reduce fat .

Fat is the main target of almost all these foods, although we now know that its effect on the body is not as bad as we thought at first. What’s more, there are several studies that suggest that whole milk, contrary to popular belief, could help you lose weight.
This is due to several issues, among which the presence of conjugated linoleic acid stands out. Linoleic acid, in addition to being one of the "good" fatty acids, from the classical point of view, would to some extent prevent the formation of fat in humans. On the other hand, calcium and its bioavailability would also play an essential role. Thus, although paradoxical, whole milk would help you lose weight more than semi-skimmed or skimmed milk .
Drink "light" and gain weight …
Another paradoxical effect, observed in "light" or "zero" drinks, as we know them here, is weight gain. Yes, despite the fact that they effectively reduce the amount of calories, the truth is that analyzes have shown not only that they do not help reduce body fat, but that many consumers gain weight.

The mechanisms behind this effect are various. The first, physiological, is explained by insulin. This hormone is the main blood sugar controller. This system is regulated by many stimuli, including taste, which encourages the body to regulate the absorption and accumulation of sugars in the blood (which might not accumulate in other circumstances).
The second is behavioral: there are reasons to think that the consumption of "light" drinks, probably due to metabolic relationships of what we mentioned, induces the consumption of sweeter and tastier foods, with more sugar. In the end, the problem is much bigger and more complex than just reducing kilocalories in drinks.
A diet food, alone, is of no use
What is needed is to learn to eat better, change habits and stick to them . This is much more important and efficient. At no time do we mean that diet foods have certain effects, but they only do so, solely and exclusively, when they are put in a full context of nutrition.
In those cases, the weight loss cannot be attributed to diet products , but to all the change in habits. And if habits are not changed, as we have said, there is no evidence to show weight loss. Also, some of the mechanisms we were talking about could work against us.
If we want to reduce body fat, the only thing we can, and must, do is change to healthy habits . That means eating better, eating a healthier diet that reduces ultra-processed foods (including "light" foods), sugars, increasing the amount of water we drink, fiber and, of course, moving more in our day to day life.
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