At the dawn of 2022, eating healthier and losing weight is, as every year, part of the "good resolutions" most valued by the people. But this year, this concern should be further reinforced given the weight gain associated with confinement. The question of the best weight loss diet is therefore more relevant than ever.
Weight gain is linked to a caloric imbalance : calorie intake is higher than expenditure. Concretely, an excess of food intake (carbohydrates, lipids and proteins) compared to energy expenditure (at rest and during physical activity).
But behind this simple statement, the multiple origins of the imbalance are hidden: eating disorders, taking certain appetite-stimulating drugs, alteration of the microbiota, pollution, psychological disorders, rich diet that is not very satietogenic, reduction in physical activity... In short, it There are dozens of factors that can influence food intake or reduce energy expenditure.
The universal treatment for weight loss: reducing caloric intake
Faced with excess weight, there are therefore two simple solutions:
- Increase physical activity to increase calorie expenditure. If the solution seems attractive, it is unfortunately not very effective for losing weight. Certainly, a regular practice of physical activity of a few hours of sport per week has a beneficial impact on weight, body composition (the proportion of lean mass and fat mass) and on health in general. We know in particular that very sedentary people have a 33% increased risk of developing overweight or even obesity. But in reality, unless you practice an intensive sport as high-level athletes can do, the impact of physical exercise for weight loss is low, certainly due to a natural compensation in food intake.
- Eat less to reduce caloric intake . Much more effective than physical activity on weight loss, this method is the basis of all popular diets (low fat, high protein, dissociated, ketogenic…).
Effectiveness of diets: what does science say?
There is no shortage of scientific arguments to justify the superiority of this or that diet or even certain nutrients with regard to weight loss. Thus, a high -protein diet increases energy expenditure more than a conventional balanced diet does. Similarly, in equal quantity, monounsaturated fats , such as those contained in olive oil, would promote weight loss compared to saturated fats (typically contained in animal fats and in palm oil). We can still cite works suggesting the weight loss interest of the fats contained in coconut oil.. These observations, based on biochemical or clinical work over a period of a few hours to a few days, do not, however, demonstrate the superiority of a particular nutrient for obtaining medium or long-term weight loss in real-life conditions.
Clinical trials conducted with a follow-up of at least one year do not confirm the hypothesis that one or another nutrient is more effective than another for successful weight loss. For example, according to recent scientific work, the ketogenic diet, which excludes carbohydrates almost completely in favor of fat, is not superior to high-carb, low-fat diets for weight loss.
Why do diets (almost) always lead to weight gain?
All low calorie diets are effective for weight loss. But a weight gain is the rule a few weeks or even a few months after their implementation. The majority of clinical trials conducted in overweight or obese people and lasting more than 6 months thus show a two-phase weight change in volunteers following a low-calorie diet:
- weight loss over a few months,
- partial or total recovery, generally from the 6th month .
The few studies conducted over a period of more than a year indicate an average final weight loss of around 3 to 5% of the initial weight . Follow-up beyond the second year is rarely available.
Weight regain following weight loss caused by a restrictive diet is explained by a relaxation of the restrictions after a few weeks . Added to this is a loss of motivation and difficulties in pursuing the efforts undertaken. On a biochemical level, weight loss is accompanied by a reduction in the secretion of leptin (satiety hormone) and an increase in the production of ghrelin (hunger hormone). Thus, satiety decreases, appetite increases and everything happens as if the body was doing everything possible to promote weight regain.
Should we necessarily limit fat to lose weight?
As you have understood, the challenge is to identify the diet that optimizes weight loss beyond 12 or even 24 months. An arithmetic calculation has often led to advocating the reduction of fat: one gram of fat provides 9 kcalories, more than double the contribution of one gram of protein or carbohydrates (4 kcalories).
Except that in reality, studies do not confirm this hypothesis. The PREDIMED study thus shows that a Mediterranean diet (therefore high in fat) does not lead to weight gain compared to a low-fat diet!
Criterion number 1: the ability to adhere to a diet for life
From all of the clinical work, there emerges a principle that is now practically a consensus: the weight loss effectiveness of a diet is predicted by the ability we have to follow it . Thus, it is easy to understand why a varied diet, such as the Mediterranean diet, not excluding any food group, can be more effective than a low-lipid diet often perceived as incompatible with "good cooking", especially when a Moderate effort is made to limit the amounts of total food intake.
Remember that adherence to caloric restriction and not the content of a diet is the key to weight loss , regardless of the nutrients consumed.
The Mediterranean diet: its benefits beyond weight
The reputation enjoyed by the Mediterranean diet is based on multiple scientific studies showing its benefits for the prevention of cardiovascular disease. This Mediterranean diet and more particularly the Cretan diet has interested researchers since the 1950s. Professor Keys' study entitled "Seven Countries Study" then showed considerably lower death and heart attack rates among Cretans compared to to other populations studied.
The way of life in Crete indeed presented many peculiarities . Their diet was rich in fruits, vegetables and legumes; it featured little red meat, a moderate amount of fish and dairy products in the form of cheese, and quality red wine consumed in moderation only with meals. Fats were mainly provided by olive oil. Butter and creams were practically absent. In addition, the life of the inhabitants of the island of Crete was distinguished by its low level of stress, by its low exposure to environmental pollution, by a social life and developed mutual aid...
In order to more closely assess the potential benefit of the Cretan diet, other studies have since been conducted. According to the recent PREDIMED clinical trial (New England Journal of Medicine, 2018), a Mediterranean diet reduces the risk of cardiovascular events by 30% in patients at high cardiovascular risk, compared to a low-fat diet. This diet also has a benefit on the risk of breast cancer (JAMA 2015).
In addition to these beneficial effects on health, the PREDIMED study, which therefore had no specific objective of restricting calorie intake, showed that the Mediterranean diet did not cause weight gain compared to a diet low in fat after nearly 5 years of follow-up . In addition, adherence to the Mediterranean diet has been associated with a reduction in fat located in the abdomen as well as a reduction in pathology related to this abdominal fat.
Conclusion: the food variety that characterizes it as well as the quality of the fats, the richness in fibers and micronutrients favor on the one hand the long-term adhesion to this diet and on the other hand the reduction of the risks of many chronic diseases. . The Mediterranean diet, with its fat intake, can now be considered an effective diet for lasting weight loss, on the only condition of paying a little attention to its dietary behavior: do not snack, do not refill, in short, limit the quantities. if we are able. In the event of eating behavior disorders (emotional eating, compulsions, etc.), restriction, whatever the diet, is never the solution. The use of an eating behavior specialist.
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