Addicted to sugar | Reader’s Digest selection

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The Mystery of Calories That Escape Metabolism

It’s ingenious. Having found a way to separate calories from sweetness in human subjects, she will be able to measure which product does what. Everything is perfect, except that the experience is not going to go as planned.

The scientist expects the highest calorie drink to trigger the strongest brain response. After all, biologically, 150 calories are more useful to the body than 0, 37.5, etc. Yet it is the 75-calorie drink that generates the most noticeable burst of brain activity. How is it possible ? If the calories stimulate the desirability of the drink, the one that contains only 75 should produce a less strong surge of desire than the one that contains 150. However, we are witnessing the opposite. If calories have nothing to do with desirability, why is the 75 calorie drink more desirable than a 0 calorie drink? It does not make sense.

By dint of turning the problem in her head, Dana Small finally realizes that the key is in the 75. All the drinks were indeed prepared to taste the same as the one that contained this number of calories of sugar, and it is precisely the one that produced the most important cerebral response. Is there more than a coincidence here?

To answer the question, she turns to the body rather than the brain and wonders how each drink is metabolized by the body. To find out, the experiment is simple. Participants come to the lab, drink one of its drinks before being “connected” to an indirect calorimeter, a device used to measure the heat produced by the body – the values ​​obtained make it possible to estimate the quantity of calories burned. This invariable reaction is called the thermic effect of food.

When the body takes in calories and uses them, it generates heat, just like a car engine heats up when it is running. The higher the calorie consumption, the greater the thermal effect.

In theory, at least, because that’s not what Dana Small observes. She vividly remembers the day the lab assistant showed her the first results. “I couldn’t believe my eyes,” she said. I knew right away that we had something new and exciting.”

A few days earlier, a young woman in her twenties participating in the study consumed the 75-calorie drink before being hooked up to the indirect calorimeter. At the expected time, his body produced a small heat spike indicating that the 75 calories were being burned.

A few days later, the same person drank the 150-calorie drink. At the calorimeter, we should have noticed a slight increase in the production of heat compared to that obtained with 75 calories. However, the data transmitted by the assistant seemed almost impossible: the calorimeter had measured nothing. As if the young woman had consumed no calories.

Which brings us back to this question: do you really have to count calories?

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Why do teenagers become obese?

It’s so unexpected that Dana Small takes over the experience. Same result. A new model seems to be taking shape: when a participant drinks a drink whose sweet taste and calories do not match, the ingested calories are not properly metabolized. Dana Small calls the phenomenon a “nutrient shift.” Maltodextrin arrives in the stomach where enzymes convert it into sugar, which in turn is absorbed into the blood. Curiously, this sugar is not burned. Like a layer of gasoline floating on the sea, it just circulates in the blood. On the contrary, when the sweet taste and the number of calories match, the calories are burned normally.

Dana Small’s research has just taken a 90 degree turn. In wanting to understand what makes sweet foods desirable, she serendipitously pinpointed a more fundamental truth. The sweet taste is not only a pleasant and arbitrary sensation. It is a metabolic signal, the first spark in a chain of biochemical processes by which sugar is transformed into energy. The taste of sugar is like the trumpet player in front of the castle: it announces not only the arrival of calories, but also the exact quantity so that the way in which they will be used is organized.

When the sweet taste and the amount of calories match, everything is fine: the calories are burned, the brain registers and remembers it. But in the face of an unexpected difference between what the tongue perceives and what the stomach receives, the metabolic process stops. “As if, not knowing what to do, the system forfeited,” says the scientist.

Does this nutrient shift have long-term consequences? The question will inspire Dana Small’s next study, which will look at an indicator of diabetes, insulin sensitivity, a disorder characterized by the inability of cells to respond properly to this crucial hormone. She tests drinks with sugar, drinks without calories and finally drinks whose sweet taste does not correspond to the number of calories. This time again, she obtains astonishing and worrying results. Drinks with a lag – and only these drinks – disrupt insulin sensitivity.

Finally, she makes this drink drink to teenagers of both sexes. The survey is particularly relevant, adolescence being a period of body transformation and brain development where young people have an excessive caloric appetite, which partly explains the excessive consumption of sugary drinks. The study had barely begun when, after submitting three participants to a blood test, Dana Small and her team discovered with dismay that two of them were already in a prediabetic state. A committee reviews the results and judges the health risk so great that it would be unethical to continue the study.

Soaring sugar levels and pre-diabetic teens are disturbing realities, but there is more bad news. The drinks offered to teenagers didn’t even taste good. The one who did best in the evaluation was entitled to a little more than “I like a little” without ever reaching the “I like enough”.

If the brain scans showed intense brain activity, it was not the pleasure that was in the party, but the “wanting”. The drink-drinking volunteers were like those mice whose ability to taste sugar had been taken away – they wanted to consume a drink they didn’t particularly like.

So we wonder: where does the idea that obesity is the result of an excess of pleasure come from? It is at the origin of the tenacious stigmatization of the obese. They would indulge themselves to excess. They would be too selfish to say, “I want more, but enough is enough.”

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The storage of calories, a necessary step in evolution

As specialists continue to claim, obesity is due to an overabundance of “foods with strong flavors”: pizza, ice cream, chicken fingers, hamburgers, etc. These products, saturated with sweet and salty calories, are said to provide such an intense feeling of happiness that they “sensitise” the brain in the same way as addictive drugs.

If only things were that simple! It is easy to decree that calories are the enemy of humanity, something that has been repeated for decades. But to discredit those poor calories is to deny the evolutionary story that made our species possible.

Seven million years ago, the brains of our ancestors measured about a third of those of our contemporaries. The brain is energy intensive. It burns a lot of calories. With their small brains, our ancestors were able to survive on a diet of low-calorie fibrous plants. They spent most of their time gathering their food and eating it. To extract the nutrients provided by this kind of diet, they had a longer and slower digestive system.

The human species has evolved and a kind of inversion has taken place. Our brains have taken on more and more volume, while the digestive system has shrunk while becoming faster. A large brain combined with less gut resulted in the optimization of foods by favoring those with the greatest caloric effect: fatty meats, nuts, grains, sugary fruits, etc. Four completely distinct populations of humans – one in Europe, two in Africa and another in the Arabian Peninsula – developed the ability to digest milk as adults, ensuring they could consume one of the few natural sources of lipids mixed with carbohydrates.

This higher-calorie diet came with a huge benefit: it bought us time. Now we spent less foraging. So we saved countless hours of wasted chewing and began to focus on what would make us more human: designing tools, erecting structures, sharing stories , myth-making, and gambling. We invented the kitchen that made our rich, edible foods even easier to digest.

In fact, calories have made humanity possible. They are the ones who fed our big brain. Our higher calorie diet did not reinforce a food compulsion, rather it freed us from an existence revolving almost exclusively around food. It freed up our time, and it allowed us to mobilize our brain around more complex tasks. We need calories, but that doesn’t mean we’re programmed to overeat, just as our need for oxygen doesn’t drive us to constant hyperventilation.

Human evolution has multiplied the reasons for curbing excess. We had to share the food with the other members of the tribe, then of the village, of the city, but especially with the children who, in terms of resources, depend for a very long time on the adults compared to the other species.

Eventually, we accomplished one of the greatest feats in the development of our species: we learned how to preserve food. 11,000 years ago, we stored cereals in places designed specifically for this purpose to protect them from humidity and rodents so that they could be consumed weeks and months after harvest. In ancient Egypt, honey was stored in clay pots. 5,000 years ago, Native Americans on the Great Plains ground buffalo bones and boiled them in steaming vats made from animal hides. The fat brought to the surface was scooped out and mixed with dried meat and berries. Result, a calorie bomb rich in lipids: pemmican. In terms of energy efficiency, this innovation has enabled a tremendous leap forward. The calories we store in the body (fat) force us to expend considerable energy, if only to lift the extra weight. But when this energy is stored outside the organism – clay pots, attics, etc. –, the efficiency is much higher.