Nutrition and Athletic Performance – What is the effect of carbohydrate, protein and fat in the athletes diet?

From: Joint Position Statement of the American Dietetic Association and Dieticians of Canada.

Journal rating:
rating: 95%
Study Quality:
rating: 70%

Overall Reliability

Article Quality:
rating: 70%
rating: 0%


  • A review of all identifiable studies with specific exclusions.


  • The paper is a systematic review / meta analysis of all relevant trials.
  • This means that the data from all similar trials has been grouped to form an overall outcome.



  • Athletes do not need a diet substantially different from that recommended in the Dietary Guidelines for Americans and Eating Well with Canada’s Food Guide.

  • Although high-carbohydrate diets (more than 60% of energy intake) have been advocated in the past, even a diet containing 50% of the energy from carbohydrate will provide an amount sufficient to maintain muscle glycogen stores from day to day.



  • The current recommended dietary allowance is 0.8 gIkgj1 body weight and the acceptable macronutrient distribution range for protein intake for adults older than 18 yr is 10%–35% of total calories.

  • Because there is not a strong body of evidence documenting that additional dietary protein is needed by healthy adults who undertake endurance or resistance exercise, the current daily recommended intake for protein and amino acids does not specifically recognize the unique needs of routinely active individuals and competitive athletes. However, recommending protein intakes in excess of the RDA to maintain optimum physical performance is commonly done in practice.

  • However, studies have also indicated that for the endurance athlete, the protein intake necessary to support turnover ranges from 1.2 to 1.4 g per kg of body weight per day.

  • Resistance (strength) exercise may necessitate protein intake in excess of the recommended daily allowance because additional protein, essential amino acids in particular, is needed along with sufficient energy to support muscle growth. This is particularly true in the early phase of strength training when the most significant gains in muscle size occurs. The amount of protein needed to maintain muscle mass may be lower for individuals who routinely resistance train because of more efficient protein use. Recommended protein intakes for strength-trained athletes range from approximately 1.2 to 1.7 per kg of body weight per day.


Protein and Amino Acids

  • Although earlier investigations in this area involved supplementation with individual amino acids, more recent work has shown that intact high-quality proteins such as whey, casein, or soy are effectively used for the maintenance, repair, and synthesis of skeletal muscle proteins in response to training

  • Protein or amino acids consumed near strength and endurance exercise can enhance maintenance of, and net gains in, skeletal muscle. Because protein or amino acid supplementation has not been shown to positively impact athletic performance, recommendations regarding protein supplementation are conservative and directed primarily at optimizing the training response to and the recovery period after exercise.



  • The Dietary Guidelines for Americans and Eating Well with Canada’s Food Guide make recommendations that the proportion of energy from fatty acids be 10% saturated, 10% polyunsaturated, 10% monounsaturated. These levels meet the acceptable macronutrient distribution range for fat which is 20%–35% of energy intake.


  • As per the results given above