Food supplements: a nutritionist reveals what really works for weight loss

In 2026, slimming dietary supplements continue to seduce. Chromium, guarana, probiotics or Morosil®: these active ingredients promise to boost metabolism and promote weight loss. However, their effectiveness remains contested by health professionals.

A nutritionist puts slimming ingredients under the microscope

Dietician-nutritionist Pauline Pied (@__paulinediet) is clear on the subject. According to her, there’s simply no such thing as a diet supplement that makes you lose weight. Indeed, every active ingredient has its very real limitations.

The probiotics can have a certain effect. However, their effectiveness varies enormously from person to person. This is because each individual has his or her own intestinal microbiota.

Chromium plays a role in regulating blood sugar levels. As a result, people who are deficient in chromium may experience a reduction in sugar cravings. For others, however, the effect is almost non-existent.

“I’ll say it straight out: there’s no such thing as supplements that make you lose weight.”

Caffeine and metabolism: limited effects

Cola and guarana are sources of caffeine. This substance can slightly increase energy expenditure. Nevertheless, the body quickly becomes accustomed to its action, especially in regular coffee drinkers.

As for Morosil®, this blood orange extract remains little-known. Its action on fats has not yet been sufficiently demonstrated. As a result, marketing promises often exceed scientific reality.

• Probiotics have variable effects depending on the microbiota
• Chromium only acts on deficient individuals
• Caffeine loses its effect with habituation
• Morosil® lacks solid scientific evidence
• Metabolism depends on factors that capsules do not alter

Why some people lose weight with a cure

Pauline Pied observes that many patients claim to have lost weight thanks to a cure. What they don’t realize is that they’ve also changed their habits. At the same time, they’ve rebalanced their diet and moved around more.

The results promised by these dietary supplements are, moreover, conditional. They presuppose a balanced diet and regular physical activity. In fact, it’s these changes that produce effects, rather than the cure itself.

The nutritionist also warns against promises of weight loss in 15 days or 3 weeks. She calls this “pure marketing”. What we see in this timeframe is water loss or improved digestion, nothing more.

The role of basal metabolism

Basal metabolism represents calories burned at rest. It depends on genetics, age, muscle mass and hormonal status. Consequently, a simple dietary supplement cannot significantly modify it.

Doing more sport will have a real impact on metabolism. Taking capsules in isolation, on the other hand, does not. Expectations created by marketing are therefore often disappointed.

Risks associated with slimming capsules

Diet supplements can also be dangerous. The caffeine contained in cola and guarana poses a problem for certain profiles. People suffering from stress, anxiety or heart disease should be cautious.

In high doses, caffeine can promotehigh blood pressure. It also accelerates heart rate and causes insomnia. These undesirable effects are often underestimated by consumers.

Chromium, on the other hand, can irritate the stomach. In high doses, it can affect kidney and liver function. Caution should therefore be exercised before taking any supplements.

Another potential danger is the cocktail of active ingredients. This is particularly true for people already taking medication or other supplements. Pauline Pied recommends seeking medical advice as soon as any pathology exists.

The nutritionist reminds us that a balanced diet provides everything the body needs. In most cases, supplementation is not mandatory. Weight loss is not one of the exceptions justifying the use of food supplements.

• dietary supplements