French health experts including Dr Laurent Chevallier have warned that overconsuming protein and protein powders provides minimal muscle growth benefits while carrying health risks.
High-protein foods such as skyr, whey, and protein pasta have expanded across supermarket shelves following fitness trends, despite French citizens already consuming more protein than official guidelines recommend.
According to the French National Agency for Food, Environmental and Occupational Health Safety, known as Anses, the recommended daily intake for adults is 0.83 grams per kilogram of body weight. However, average daily consumption in France has reached 1.4 grams per kilogram of body weight. Anses is the public body responsible for evaluating health and environmental risks in France to inform consumer guidelines.
Dr Laurent Chevallier, a nutrition doctor and author of The Fascinating Power of Your Mitochondria published by Editions Robert Laffont, stated that protein has become a new dietary trend, but protein requirements across the general population are already fully met.
Protein Needs for Strength and Endurance Athletes
Athletes require higher protein levels than sedentary individuals to support muscle repair. Nicolas Aubineau, a sports and clinical dietitian-nutritionist, stated that individuals doing intensive cardio can increase intake to 1.5 grams per kilogram per day. Those performing intensive strength training or bodybuilding can consume between 1.8 grams and 2 grams per kilogram of body weight daily.
Anses classifies any daily protein intake exceeding 2.2 grams per kilogram of body weight as high. Chevallier emphasized that consuming excess protein beyond these levels is useless for building muscle mass, as muscle growth also depends on other factors such as adequate hydration and oxygenation.
Catherine Coirault, a research director at the French National Institute of Health and Medical Research, known as Inserm, explained that muscles require amino acids to build their own proteins. Inserm is France's premier public research organisation dedicated to biological and medical science. Coirault warned that without mechanical stress from physical exercise, increasing protein intake will have no effect on muscle growth.
Kidney Health and Digestive Side Effects
When the body receives more amino acids than it requires, the excess is metabolized, and nitrogen is excreted as urea through urine. Medical professionals previously suspected high protein diets of causing kidney damage, but Coirault noted that studies consistently show excess protein is not toxic to healthy kidneys, posing a risk only to individuals with pre-existing chronic kidney disease.
Other physical complications remain a concern. Aubineau highlighted that an excessive intake of protein can overload the digestive tract, leading to symptoms such as bloating and diarrhea.
Contamination Risks in Ultra-Processed Protein Powders
While Chevallier noted that excessive protein intake rarely occurs through normal food alone, many athletes resort to commercial protein powders. Chevallier stated that such supplementation is unjustified for athletes and can be dangerous due to the ultra-processed nature of these products.
Protein powders often contain numerous artificial additives, including sweeteners, flavorings, and thickeners, which are currently being studied for potential long-term health consequences.
A major study published on April 24 by Inserm, titled Doping and Doping Practices in Sports Environments, highlighted significant contamination risks in dietary supplements. Researchers discovered that up to 58 percent of tested supplement samples contained concentrations of prohibited substances high enough to trigger positive anti-doping controls.
The banned substances identified in the study included anabolic steroids. Coirault emphasized that while anabolic steroids promote muscle growth, they carry toxic health effects, making careful verification of product composition and origin essential for consumers.
