Sustainable weight loss starts with a simple idea, but one that is often misunderstood: the body does not function like a switch. Abruptly reducing calories for three weeks and then returning to old habits produces exactly the opposite result of what is sought. The High Authority of Health (HAS) actually treats overweight as a chronic situation, with follow-up to be reassessed after six to twelve months, not as a one-time challenge.
Modest weight loss: why aiming lower changes everything
Have you ever noticed that the most ambitious goals are often the ones we abandon the fastest? Losing fifteen kilos in three months sounds motivating on paper. In practice, the necessary restriction is exhausting, frustrating, and leads to regaining weight.
HAS indicates that a sustained loss of 3 to 5% of body weight can already improve blood sugar and triglycerides. Between 5 and 10%, it’s blood pressure and cholesterol that improve. Specifically, for a person weighing 90 kg, this represents a goal of three to nine kilos, no more.
This framework changes the perspective. The goal is no longer an arbitrary number on the scale, but a measurable medical benefit in the short term. And above all, an achievable goal is easier to maintain over time.
Several resources detail the dietary and behavioral levers associated with this approach, including content dedicated to weight loss on Santé Quotidienne that addresses these mechanisms on a daily basis.
Caloric deficit without deprivation: the adjustment that matters
The caloric deficit is the only mechanism that causes fat loss. The body expends more energy than it receives and draws from its reserves. Up to this point, most articles stop.
The point that these contents skim over is the extent of the deficit. An overly aggressive deficit (skipping meals, eliminating an entire food group) triggers a stress hormone response. Cortisol increases, hunger becomes obsessive, and metabolism slows down to compensate.
A moderate deficit is around a few hundred calories per day, no more. Here’s how to achieve it without complex calculations:
- Reduce portions of starchy foods by about a quarter, without eliminating them. The brain needs glucose to function properly.
- Increase the proportion of vegetables at each main meal, which increases the volume on the plate while reducing caloric density.
- Maintain sufficient protein intake (meat, fish, eggs, legumes) to preserve muscle mass, which consumes energy even at rest.
- Limit liquid calories (sodas, industrial fruit juices, alcohol), which are often underestimated in the daily balance.
This dietary adjustment is nothing spectacular. That’s precisely why it works in the long term. Drastic diets, on the other hand, weaken health and lead to yo-yo effects.
Physical activity and weight loss: what exercise really changes
Moving is not just about burning calories during exertion. Regular physical activity increases the basal metabolism, which is the energy the body expends at rest. The greater the muscle mass, the higher this baseline expenditure.
Why does this detail matter? Because during a caloric deficit, the body tends to lose muscle as much as fat. Exercise protects muscle mass during weight loss. Without physical activity, a significant portion of the weight lost comes from muscle, which slows metabolism and facilitates regaining weight.
The type of exercise does not need to be intense to produce this effect. Regular brisk walking (thirty minutes several times a week) combined with simple muscle strengthening (squats, push-ups, bodyweight exercises) already yields concrete results.
A common pitfall: compensating for effort with food rewards. An hour of brisk walking does not compensate for a sweet dessert. Physical activity is a complementary lever to diet, not a license to eat more.
Eating habits and sleep: the underestimated levers
The regularity of meals plays a role that many underestimate. Skipping breakfast or snacking in the evening alters the body’s hormonal response, particularly insulin. When insulin remains elevated constantly, fat storage is favored.
Eating at fixed times stabilizes blood sugar and reduces cravings. Three structured meals are better than five disorganized eating occasions. If a snack is necessary, a fruit or a handful of nuts is sufficient.
Sleep also factors into the equation. Chronic lack of sleep increases ghrelin (the hunger hormone) and decreases leptin (the satiety hormone). The result: we eat more the next day without even realizing it. Getting enough sleep directly contributes to weight control.
Weight loss medications: the risks of a dangerous shortcut
GLP-1 analogs (which include some high-profile treatments for obesity) are subject to enhanced monitoring by the ANSM. These medications must be prescribed by a doctor, dispensed at a pharmacy, and accompanied by regular medical follow-up.
Purchasing them online, outside of a prescription, exposes one to potentially serious complications. The ANSM reports a persistence of misuse, with digestive side effects and more serious risks documented in pharmacovigilance reports.
These treatments do not replace lifestyle changes. They are reserved for specific medical situations (obesity with complications), not for a simple desire to lose a few kilos before summer.
The HAS guide for 2024 recommends evaluating each situation according to its overall complexity, not just based on BMI. History of failure, eating disorders, social context: all these factors guide the management. A doctor or dietitian remains the first point of contact to build an appropriate strategy, far from standardized solutions that ignore these individual realities.
