Few topics in sports nutrition are as polarizing as macronutrients. One camp swears by high carbs, another by high protein, another by low carb and high fat. The evidence points to something less dramatic: carbohydrates, protein and fat each do a job the others cannot do. Remove or neglect one, and training suffers.
The Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine take the same view. Their joint position is that performance and recovery are enhanced by well-chosen nutrition strategies. Their guidance covers the type, amount and timing of intake rather than crowning a single “best” macronutrient.
Carbohydrates: the fuel for hard training
Carbohydrate is stored in muscle and liver as glycogen. Storage is limited, and running low on muscle glycogen is one factor behind fatigue and exhaustion in prolonged exercise. Researchers also consider liver glycogen depletion a major contributor to fatigue in endurance exercise.
That is why elite endurance athletes are typically advised to have high carbohydrate availability before, during and after high-intensity sessions. A diet too low in carbohydrate can leave little glycogen rebuilt between sessions, leading to chronic fatigue.
The sports nutrition position stand puts typical intakes at 3–10 g per kg of body weight per day, rising to as much as 12 g/kg for extreme, prolonged activity. The same summary notes that for fast recovery, intake of about 1.0–1.2 g/kg per hour for the first 4–6 hours after exercise is suggested.
Protein: repair, adaptation and muscle building
Training provides the stimulus, and protein provides the building material. The International Society of Sports Nutrition (ISSN) reports that exercise, especially resistance training, and protein intake both stimulate muscle protein synthesis, and the effects are synergistic.
For most exercising people, 1.4–2.0 g of protein per kg of body weight per day is sufficient for building and maintaining muscle. That is well above the general-population allowance, as the RDA for healthy adults is 0.8 g/kg per day. Spreading protein across the day works well, and a general guideline is about 0.25 g/kg of high-quality protein per meal, or 20–40 g in absolute terms.
Fat: hormones, vitamins and long-lasting energy
Fat is often treated as the enemy, but it does several essential jobs. For athletes it provides energy at lower exercise intensities, aids absorption of vitamins A, D, E and K, protects vital organs and supports hormone production.
The usual guideline is that 20–35% of total energy should come from fat, with individual needs varying. Eating fat does not cause weight gain by itself: weight gain comes from an energy surplus, not from fat as such. One practical tip is to eat fat-rich foods in meals away from training sessions.
Why “balance” beats extremes
Each macronutrient covers a different need: carbs for fuel and glycogen, protein for repair and adaptation, fat for hormones, vitamin absorption and baseline energy. Cutting one forces the others to compensate for jobs they are not designed to do. Notably, the joint position stand reviewers did not find enough evidence to support ketogenic or carbohydrate-restricted diets for improving athletic performance.
Needs also change with the training phase. Heavy endurance blocks call for more carbohydrate, strength phases lean on protein, and fat keeps hormones and vitamin status in order throughout.
A practical way to build your plate
- Carbs: whole grains, potatoes, rice, oats, fruit, legumes, with more on heavy training days.
- Protein: eggs, dairy, fish, poultry, lean meat, tofu, legumes, spread across 3–5 meals.
- Fats: olive oil, nuts, seeds, avocado, oily fish.
- Individualize: a registered sports dietitian can tailor the ranges above to your sport, body weight and goals.
This article is for general information and does not replace advice from a physician or registered dietitian.
Sources
- Academy of Nutrition and Dietetics, Dietitians of Canada & ACSM: Nutrition and Athletic Performance (joint position statement, 2016)
- Summary of the position statement’s recommended intakes: My Health Career
- International Society of Sports Nutrition: Position Stand: Protein and Exercise (2017)
- ISSN full text: Protein and Exercise, J Int Soc Sports Nutr
- Hearris et al., Nutrients 2018: Regulation of Muscle Glycogen Metabolism during Exercise
- Carbohydrate for athletic training and performance (review): PubMed
- NSW Institute of Sport: An athlete’s guide to understanding dietary fat
- Overview of the position statement’s carbohydrate, protein and fat guidance: Cronometer