Summer body: do diets give the same results for everyone?

With the arrival of sunny days, “bikini goals” or summer bodies make the cover of magazines. The headlines promise readers infallible methods for rapid and effective weight loss, for a sculpted, more aesthetic or more athletic body, combining both a flat stomach and tablets of chocolate. Indispensable to pass the “test” of the swimsuit this summer. But what about these “miracle” formulas? Do frequently suggested methods work? And are we all equal when it comes to weight loss? Canal Détox takes stock of the scientific research that has attempted to better understand how our weight is finely regulated.

the overweight and theobesity are commonly linked to an imbalance between energy intake (the calories consumed) and energy expenditure (activity physical): energy intake exceeds expenditure over a long period. Weight loss strategies relayed in the media most often follow this logic, advising both an increase in physical activity and a restriction of food intake.

Is there a miracle formula?

A very large number of studies have already focused on theeffectiveness of diets diets based on calorie restriction that promise maximum results in a very short time. For scientists, however, their effectiveness remains limited in the long term. While weight loss in the first six months can sometimes be seen, between one and two thirds of the lost weight would be regained within five years. However, studies agree that a weight loss, even of 5%, would lead to significant metabolic benefits: lower glucosedecrease in the level of triglycerides in the blood, reduction of cardiovascular risks.

All equal ?

Along with the limited effectiveness of diets, scientists have found huge inter-individual variation in how our bodies regulate weight, including when food intake tracking is tightly controlled in research. Results that underline the importance of focusing on individual trajectories to understand the mechanisms of weight loss and develop personalized solutions, adapted to each individual.

This variability, which can be designated by the term “individual susceptibility” has been demonstrated through several epidemiological studies. For example, as part of a study conducted in the early 1990s in Quebec, researchers invited monozygotic twins to all consume 1,000 calories more per day, compared to their usual consumption, for about 100 days. At the end of the study, inequalities in weight gain and mass fat were observed, but the variability was lower within the same pair of twins (who therefore shared the same heritage genetic) than between different pairs. Similar results were obtained vis-à-vis weight loss, by studying twins subjected to a calorie-restricted diet.

Genetic factors could therefore be involved in the development of obesity. An individual is two to eight times more likely to be obese if members of his family are themselves. Multiple teams have identified many genes involved in weight gain, obesity severe and/or complications of obesity. Another study has also shown that thinness is partly explained by genes. It should be noted that if each gene taken individually has only a small role on body mass and composition, the contribution of these genes becomes significant when they interact with external factors such as energy imbalance.

In addition to genetics, age, stress, hormone or the sleep and biological rhythms, are all factors that can influence weight regulation and which intervene differently from one person to another. For example, scientific studies have shown that the duration from sleep had a impact on weight gain or loss. Recently, the results from a study conducted in the United States showed that sleeping longer facilitated weight loss. Lack of sleep being considered a recognized risk factor for obesity, these results once again underline the importance of also exploring the relationship between weight and sleep to promote weight loss on an individual basis.

The role of the brain in weight regulation

To better understand the mechanisms associated with weight gain and loss, scientists cannot overlook the key role of brain. Research teams are more specifically interested in studying the mechanisms involved in the brain and the key action of ” sensors energy” in the regulation of food intake and body weight. These molecules act like the fuel gauges in our carsthey signal to our brain our needs according to the level of our energy reserves.

Among these molecules studied for more than 20 years, we find leptin or “satiety hormone”: it is secreted by the adipose tissuein proportion to the fat reserves in the body, and regulates the appetite by controlling the feeling of satiety. Many studies revealed that leptin transport and signaling was altered in obese subjects and Overweightpartly explaining dysfunctions in the regulation of appetite, since it is more difficult for satiety information to reach the brain.

Regular physical activity and less rich diet, the winning cocktail

While research agrees that there is no “silver bullet” solution to effective weight loss that works for everyone, the health benefits of regular physical activity have also been demonstrated.

Scientists also recommend accompanying physical activity with a diet less rich in sugars, saturated fats, salt and calories and higher in fiber and fruits and vegetables. This is how the Nutri-Score logo was born, developed to help consumers choose products of better nutritional quality on the shelves, and encourage manufacturers to improve the nutritional quality of their products.