Sports nutrition is measured less by the intrinsic quality of a food than by the ratio of energy consumed to energy expended during training. This gap, called energy availability, conditions muscle recovery, hormonal regulation, and medium-term progress. Comparing macronutrient intake according to the type of effort helps identify where the most common discrepancies lie between what athletes eat and what their bodies actually need.
Carbohydrates, proteins, fats: distribution of macronutrients according to the type of effort
The ideal proportion of each macronutrient varies significantly depending on whether the effort requires endurance, strength, or a mix of both. The differences between these profiles explain why the same meal does not yield the same results for a long-distance runner and a weightlifter.
| Macronutrient | Main Role | Priority in Endurance | Priority in Strength/Bodybuilding |
|---|---|---|---|
| Carbohydrates | Immediate fuel (muscle glycogen) | High | Moderate |
| Proteins | Muscle repair and synthesis | Moderate | High |
| Fats | Long-lasting energy, absorption of vitamins | Moderate to high | Moderate |
An endurance athlete derives the majority of their energy from carbohydrates stored as glycogen. When these reserves are depleted, performance drops sharply. Proteins remain necessary, but their relative share on the plate is lower than for a strength practitioner, whose priority is to stimulate muscle synthesis after each session.
Fats, often reduced to a minimum by reflex, ensure the intake of fatty acids and participate in the transport of certain fat-soluble vitamins. Eliminating them exposes one to deficiencies that manifest as diffuse fatigue and slowed recovery.
To delve deeper into these questions of dietary balance applied to sports, you can access the nutrition page of Le Monde du Sport, which gathers additional resources on the subject.
Energy availability: the unknown risk of under-supply in sports nutrition
Eating healthily does not guarantee eating enough. This is one of the least addressed points in traditional nutrition guides, while the IOC consensus on REDs (Relative Energy Deficiency in Sport), updated in 2023, places it at the center of concerns.
What REDs changes in nutritional approach
REDs does not only concern female athletes or those looking to lose weight. It affects any athlete whose caloric intake does not cover the expenditure related to training, even with a diet perceived as balanced.
The consequences go beyond simple performance decline. Insufficient energy availability can affect bone health, immune function, hormonal regulation, and cognitive abilities. The IOC consensus also mentions insufficient carbohydrate intake as an aggravating factor, along with psychological components related to dietary restriction.
Specifically, a runner who increases their training volume without adjusting their meals exposes themselves to this imbalance. Persistent fatigue, repeated injuries, and stagnation in performance are the most common warning signs.
Adapting diet to training load
The Runner’s Clinic talks about “periodizing one’s diet” according to the training plan. The principle is logical: phases of intensive training require a higher caloric and carbohydrate intake than periods of rest or maintenance.
- During load periods (high volume or intensity), increase the proportion of carbohydrates in meals before and after sessions to maintain glycogen stores
- During recovery or downtime, slightly reduce carbohydrate intake while maintaining proteins and fats to support tissue repair
- Before a competition, prioritize easily digestible foods rich in complex carbohydrates in the hours leading up to the effort
This approach avoids the trap of a rigid diet that does not take into account the variations in energy expenditure from week to week.
Dietary supplements for athletes: caution regarding composition
The market for dietary supplements aimed at athletes represents a rapidly growing sector, but the quality of products is highly variable. In an opinion published in July 2024, ANSES warned about the risks associated with certain supplements intended for bodybuilding or weight loss.
The main problem concerns the possible presence of banned or dangerous substances in products sold freely. For athletes subject to anti-doping controls, this issue is critical: a contaminated supplement can lead to a positive test without the athlete intending to dope.
What to check before buying
- Look for products with a certification recognized by anti-doping organizations, which guarantees the absence of banned substances
- Avoid supplements with vague ingredient lists or that promise spectacular results on muscle mass or fat loss
- Prioritize solid food as the main source of nutrients, with supplements only needed to fill a documented deficit (iron, vitamin D, for example)
A supplement does not replace a meal structured around whole foods. Proteins from chicken, fish, eggs, or legumes are more effectively assimilated by the body when they are part of a balanced meal.
Meal timing and muscle recovery: what the data shows
The timing of when you eat is as important as what you eat. Nutrition before effort conditions the level of energy available, while the post-training meal directly influences recovery speed.
Before a session, a meal consumed one to three hours before the effort allows time for digestion to occur without causing gastric discomfort. This meal should contain a base of complex carbohydrates (rice, oats, whole grain bread) and a moderate source of protein.
After effort, the recovery window of the first hours is when the body replenishes its glycogen stores and repairs the muscle fibers that were stressed. Combining carbohydrates and proteins in this meal accelerates this process. A quality fat intake (almonds, fatty fish) complements the replenishment without burdening digestion.
The performance gap between an athlete who structures their meals around their sessions and another who eats randomly widens over the weeks. Nutritional consistency produces cumulative effects on recovery and adaptation to training. The central data remains energy availability: as long as intake covers expenditure, the body has the resources to progress.
