First and foremost, energy and macronutrient needs must be met, specifically for carbohydrates and protein. This ensures that glycogen stores are replenished, and there are amino acids available to repair tissue and build muscle. Fats also must not be forgotten, as they provide essential fatty acids and fat-soluble vitamins (vitamin A, D, E, K), as well as provide energy. Restricting fat in non-obese adolescents restricts growth and development.
Along with consuming enough macronutrients (carbs, protein, fats), it is imperative to consume enough micronutrients (vitamins and minerals). It is best to get these from food, not just from supplements. Micronutrients are important for energy production, hemoglobin synthesis, bone health, immune function, and protection from oxidative damage. It is also important to drink lots of fluids to replenish the body of those fluids lost from sweat.
Since meeting energy requirements is an athlete’s first priority, let’s go over that first. Calories only come from macronutrients (carbs, protein, and fats); if you eat more calories than you burn, you gain weight, and if you burn more than you eat, you lose weight. For an athlete, you need to make sure to at least eat what you burn to make sure you are fully replenishing your system and maintaining your weight. For easy calculations:
1g of carbs = 4 calories
1g of protein = 4 calories
1g of fats = 9 calories
For an athlete, you should aim for having 55-60% of your daily caloric intake come from carbs, 15-20% come from protein, and 20-25% come from fats (can be up to 30% in adolescents). With fats, try to have no more than 10% of your daily energy intake come from saturated fats. It depends how many calories you burn daily, but you should definitely be eating at least 2000 calories a day. Try to think of it as eating at least 40 calories/ kg of body weight per day. In terms of carb intake for an endurance athlete, you should aim to eat ~6-10 g/ kg of body weight per day. For protein, aim for ~1.2-1.5 g/ kg.
Eg.) For a 120 lb (54kg) person, you should eat a minimum of 2200 calories/ day. For an athlete, I would say minimum 2500 calories. If we go off 2500 calories, your macronutrient breakdown would be as follows:
Carbs: 60% daily intake = 1500 calories = 375 g = 7 g/ kg of body weight
Protein = 15% daily intake = 375 calories = 94 g = 1.6 g/ kg of body weight
Fats = 25% daily intake = 625 calories = 70 g = 1.3 g/kg of body weight
Where’s the best place to get these macronutrients? From whole foods! For carbs, go for breads, cereals, grain, veggies, and fruits. For protein, aim for animal based protein. If you’re going for plant-based protein, you may need to increase your daily protein intake by 10% because plant-based proteins are harder to digest compared to animal protein (can increase it to 1.8 g/ kg of body weight). Also, sports drinks contain carbs and electrolytes that provide fuel for muscles, maintain blood glucose, and decrease the risk of dehydration.
Here is a breakdown of what to eat pre-, during, and post-competition:
Pre-Comp Meal:
– Eating before improves performance
– Try to eat 200-300 g of carbs in meals consumed 3-4 hrs before competition
– Goal is to not be hungry, but to also have an empty GI tract
Pre-Comp Snack:
– High in carbs (for blood glucose maintenance), moderate in protein, low in fats and fibre (to facilitate gastric emptying and minimize GI distress)
During Competition:
– Provide carbs to maintain blood glucose levels, and fluids to replace losses
– 0.7 g of carbs/ kg per hour extends endurance performance
– Try to get carbs from glucose, not fructose (aka something more than fruits)
Post-Comp Meal:
– Carbs replace muscle glycogen levels and ensure rapid recovery
– Protein provides amino acids to build and repair muscle tissue
– Aim for 1.5 g/ kg of carbs during the first 30 min after exercise, and again every 2 hrs for 4-6 hrs post-comp
-> this gives higher glycogen levels
– Glucose and sucrose appear equally effective, fructose is less effective (that’s why white bread and chocolate milk are good recovery foods)
In terms of fluid intake, you should aim for 400-600 ml 2 hrs before exercise, and 150-250 ml every 15-20 min during exercise. Make sure to consume adequate fluids post-exercise to refill and replenish the body. You need more fluid intake at higher altitudes, so make sure to keep hydrated.
As mentioned at the beginning, micronutrients are important for energy production, hemoglobin synthesis, bone health, immune function, and protection from oxidative damage. These should all be covered in a well-rounded diet, so make sure to eat a variety of foods. Here is a breakdown of which micronutrients help with each function:
Energy production: thiamin, riboflavin, vitamin B-6, niacin, pantothetic acid, biotin
Red blood cell and tissue repair: folate, vitamin B-12
Antioxidant Nutrients: Vitamins A, E, C, Beta-carotene, selenium
Hemoglobin formation: iron
Females, specifically adolescent females, have a higher risk for being iron deficient, so it is important to make sure these athletes are getting enough iron in their diets.
References
Position of the American dietetic association, dietitians of Canada, and the American college of sports medicine: nutrition and athletic performance (2000). Journal of the American Dietetic Association, 100(12), 1543-1556.
Nutritional concerns for the child and adolescent competitor (2004). Nutrition, 20(7-8), 620-631.