Disclaimer
We are not certified dietitians or nutritionists, so we can only provide a general guidance to your patients and clients. It's essential for us as health professionals to have a general understanding of nutrition and its application to training in order to help our patients and clients navigate through all of the false information, as well as teach them to use nutrition as a tool to optimize their performance. It is also important to be able to recognize any red flags related to a client's nutrition or exercise habits and refer them to a professional if necessary.
Carbohydrates
Nutritional Value: 4 calories/gram
Primary Role: energy source
Carbs are stored as glycogen via the glycogenesis process* (link to it) and serve as the body's initial + main source of energy during activity. This topic is discussed more in depth in the bioenergetics section.
Athletes can adapt to low-carb diets and force their bodies to become more dependent on fat for energy.
Recommendations
45 - 65% total caloric intake
Aerobic endurance athletes: 8 - 10 g/kg
Anaerobic strength, sprint, or skill athletes: 5 - 6 g/kg
Lipids
Recommendations
Sedentary: 20 - 30% total caloric intake, less than 10% of which should be saturated fats
Athletes: 20 - 50% total caloric intake, at least 15% of which should be saturated as to not stunt testosterone production
Nutritional Value: 9 calories/gram
Primary Roles
Energy source
Hormone regulation
Transport fat-soluble vitamins
Cell membrane formation
Insulation and protection
Protein
Nutritional Value: 4 calories/gram
Primary Role: tissue repair
Recommendations
Caloric intake is inversely proportional to protein consumption. If you have a low caloric intake, a high proportion of those calories need to be from protein. And the opposite is true for a high calorie diet; low proportions of protein should be consumed if total caloric intake is high.
10 - 15% total caloric intake; but 10 - 35% is acceptable
Sedentary: 0.8 g/kg
Aerobic: 1.0 - 1.6 g/kg
Anaerobic: 1.4 - 1.7 g/kg
Vegans might need 2.0+ g/kg to ensure they consume all of the essential amino acids
20 - 48 g/day has been proven to stimulate acute muscle protein synthesis; intakes greater than this has shown no benefits.
Amino Acids
Primary Role: muscle growth, tissue repair, enzyme and hormone synthesis, cell repair and synthesis
Essential: cannot be made in the body, needs to be consumed
Nonessential: can be made in the body, not necessary to consume
Conditionally essential: typically nonessential, except during times of illness or stress
A few good sources of essential amino acids are quinoa, flaxseed, chia seeds, and lentils. For our non-vegan friends, lean meat, poultry, dairy, and eggs also provide the AAs you need to take advantage of their benefits.
Nutrition for Aerobic Endurance Performance and Recovery
Carbohydrates: 8 - 10 g/kg
Protein: 1.0 - 1.6 g/kg (especially if training for 90+ minutes)
Eating before competition
4 hours before: 1 - 4 g/kg carbohydrates, 0.15 - 0.25 g/kg protein
2 hours before: 1g/kg carbohydrates, no protein
Post Exercise:
1.5 g/kg of carbohydrates should be consumed within 30 minutes after stopping exercise. 10 g/kg of protein within 3 hours after stopping exercise is generally accepted, but sooner may be better.
Some studies have shown that eating a combination of protein and carbohydrates after exercise attenuates muscles breakdown and soreness, while increasing muscle protein synthesis. The literature on this is not conclusive and doesn't provide an ideal amount or time period, but it might depend on the type and duration of exercise and the fasting state of the individual prior to exercise.
Nutrition for Anaerobic Strength Training and Hypertrophy
Carbohydrates: 5 - 6 g/kg
Protein: 1.4 - 1.7 g/kg
Post Exercise:
3:1 or 4:1 carbohydrates to protein ratio
20 - 48g of protein is beneficial to increase muscle synthesis. High protein intake shows to have no benefits or physiological concerns. Muscle sensitivity to amino acids and their muscle growth and tissue repair abilities is increased for up to 48 hours after exercise.
Nutrition for Weight Loss
Ultimately, weight loss comes down to a negative calorie balance. It's recommended to decrease their caloric intake by 500 - 1,000 calories; any more than this could be dangerous.
1 lb = 3,500 calories
1 - 2 lbs/week or ~1% of body weight/week is safe and sustainable weight loss
There is no one-size-fits-all diet. Both low-fat and low-carb diets have shown to help people lose weight, as long as they're adhering to it and are consuming less calories than they are burning through exercise and daily life. No significant difference in weight loss has been seen between low-fat and low-carb diets.
However, a lot of the weight lost during dieting comes from lost muscle because synthesizing and maintaining muscle requires so much energy. If an athlete is dieting but wants to maintain muscle, they should consume 1.8 - 2.7 g/kg of protein.