Building a sound and sustainable nutrition plan that powers growth and performance.

Participation in athletics can be an important contributor to an adolescent’s physical, cognitive and emotional development. However, sports also impose increased physical demands that can compete with the nutrients needed for their developing bodies. Inadequate nutrition for young athletes can have effects that extend beyond the sporting world, if not accounted for.

If you work with young athletes, you can help by emphasizing, among other things, their nutritional needs for recovery, growth and development, as well as the specific risks they may face. (See “Sustainable Habits Start Here,” below.)

While youth coaches, trainers and parents often emphasize the need to “get in enough calories” for training and recovery, there is little discussion on how many calories that is or what the ideal macronutrient distribution of those calories would be. This article examines these considerations for youth athletes—and how fitness professionals can (within scope of practice) help them leverage the power of good nutrition to enhance performance while powering health and growth.

Energy Requirements

Young athletes require energy—derived from adenosine triphosphate (ATP) production and in the form of calories—to perform, recover and grow. Too little energy, and the athlete’s body must start to make some physiological sacrifices, which could range from diminished sports performance to impaired physical development. Too much energy will be stored in the form of body fat, which can lead to both decreased performance (due to alterations in power-to-weight ratios) and potential exposure to negative health effects, either now or later in life (Desbrow 2021).

There are a variety of methods for calculating energy requirements, each with benefits and drawbacks. One approach to consider for coaches and trainers without access to advanced methods would be to calculate an athlete’s resting metabolic rate (RMR) using the Harris-Benedict equation, then determining the total caloric requirements (TCR) using an activity multiplier.

The activity multiplier is a factor by which the RMR is multiplied to determine the TCR for the athlete. The activity multiplier can range from 1.2 for sedentary individuals to 2.0 for athletes engaging in very rigorous activities, such as twice-a-day training (Fink & Mikesky 2018).

Equations to Consider

Fink & Mikesky share these two versions of the Harris-Benedict Equation, which were created for adult men and women based on weight in kilograms, height in centimeters and age in years.

Men

RMR = 66.5 + (13.7 × weight in kilograms) + (5 × height in centimeters) – (6.8 × age)​

Women

RMR = 655 + (9.6 × weight in kg) + (1.8 × height in cm) – (4.7 × age)​

However, Desbrow advises against using adult-based equations (such as the Harris-Benedict equation) to predict RMR in young athletes because research has shown these calculations can be off by as much as 300 kilocalories per day. More recently, a new equation has been developed to calculate the needs of adolescent athletes (ages 13.1–19.7):

Adolescent Males

RMR (kcal/day) = 11.1 × body mass (kg) + 8.4 × height (cm) – 340

Adolescent Females

RMR (kcal/day) = 11.1 × body mass (kg) + 8.4 × height (cm) – 537

Of course, this is resting metabolic rate. Young athletes’ actual daily caloric needs will vary based on their body composition, the intensity of activity they perform and the consistency of that activity. There are also some studies that spell out estimated energy requirements of children and adolescents ages 1–17 that include breakdowns for light, moderate or heavy physical activity (Torun 2007).

Bear in mind that no equation is foolproof or absolute. There will be variability in these numbers based on the body composition, intensity of activity and consistency of activity. Coaches and trainers should therefore understand that this is simply a starting point and move forward collaborating with qualified nutrition professionals before any major dietary changes are made. Also, keep in mind the potential concerns for the development of eating disorders in this population (see Sustainable Habits Start Here,” below).

Essential Nutrients and Nutrition for Young Athletes

Now that we have discussed the basics of determining the energy need, we need to determine the most effective way for the young athlete to get these calories through quality nutrition. This speaks to the macronutrient distribution that is ideal for the athlete.

Carbohydrates

Carbohydrates are the primary energy source for youth athletes. Their inclusion is essential for recovery and performance, as well as for normal development and growth. While diet plans do exist that exclude carbohydrates, they are not recommended for youth athletes. Ideally, the athlete should be encouraged to make sustainable food choices that will enhance their performance without excluding food groups.

The amount of carbohydrates needed will depend on a variety of factors, such as intensity and duration of sport. The International Society of Sports Nutrition recommends athletes get 5–8 grams of carbohydrates per kg of body weight per day for athletes training a moderate amount of intense exercise (Kreider et al. 2004). Desbrow suggests that young athletes differ from adults in the number of different sports in which they participate concurrently, which can affect energy demands per day.

Intake of a small amount of carbohydrates before a session may benefit a young athlete’s performance, especially if they haven’t had a recent snack or meal. Coaches may want to highlight how to select high-quality carbohydrates over highly processed foods, utilizing label reading and other strategies and resources.

Protein

Protein is an essential nutrient that has both structural responsibilities, such as muscle repair and growth, and functional responsibilities, such as the synthesis of enzymes. The protein requirements for an athlete can range quite substantially based on the sport involved, but most youth athletes will need approximately 1.5 g of protein per kg of body weight per day. Desbrow 2021 suggests dividing this intake into 0.3 g/kg servings divided among five meals and snacks, with one of them being part of post-exercise recovery.

Fats

Dietary fat is needed for many vital functions, such as the production of hormones, absorption and utilization of fat-soluble vitamins, and the function of the nervous system. Although there is no specific calculation to determine the dietary fat need for young athletes, we can extrapolate this requirement by subtracting the calories allotted to protein and carbohydrates from the TCR.

Summary of Macronutrient Needs

In sum, the calorie intake of a youth athlete should have a distribution breakdown of about 15% from protein, 50%–60% from carbohydrates and 25%–35% from dietary fats, with an emphasis on quality as well as on the variety of micronutrients included in the food sources selected.

Micronutrients

While an exhaustive analysis of micronutrients is beyond the scope of this article, discussion of the following micronutrients can be of particular benefit to young athletes.

Iron

Iron is needed for the binding of oxygen in red blood cells. Deficiency, often due to lack of intake, is a concern for both males and females, but menstruating athletes are at a particular risk for iron deficiencies that can negatively impact athletic performance.

Encourage parents to ensure adequate consumption and nutrition for young athletes. Per Purcell et al. (2013), that is

• males and females ages 9–13: 8 mg/day
• males ages 14–18: 11 mg/day
• females ages 14–18: 15 mg/day

Calcium

The body requires calcium for bone growth, bone repair (including postexercise) and muscle contraction, among other functions. Due to rapid growth and development during the adolescent years, dietary calcium consumption is necessary to make up for the 300 g/day rate of calcium accretion.

At a 25%–35% absorption rate from food, this would mean young athletes should consume 900–1,200 g minimum per day (Desbrow 2021).

Vitamin D

This vital nutrient supports bone growth and development, but it also has other roles important for health and recovery. Therefore, the youth athlete should be encouraged to consume 600 International Units per day (Purcell et al. 2013).

Electrolytes

The loss of electrolytes (sodium, potassium, chloride, calcium and magnesium) through perspiration can have impact an athlete, particularly if they are exercising for a longer duration (more than 60 minutes) or in a hot climate or location. Consider connecting parents with information on use of electrolyte-replacement drinks in these situations and noting that these drinks should not be needed otherwise (Purcell et al. 2013).Consuming such drinks unnecessarily will merely offset the intake of more valuable calories and can increase added sugar intake.

Choosing the Best Sources

Nutrition is not just a numbers game. Youth trainers and coaches can also help parents and athletes understand how to develop a healthy, sustainable relationship with food. This will benefit the athlete’s performance, growth and development. As such, whenever possible, the primary nutrients should be sourced from whole foods rather than processed foods or supplements.

Processed foods hold many artificial ingredients and often contain added sugar and sodium, both of which can ultimately lead to long-term healthdetriments. Even foods that are supplemented or enriched are unlikely to provide the myriad benefits of whole foods or the wide array of micronutrients that are needed for every athlete, but in particular for those who are developing and growing.

Supplements are neither recommended for this age group nor a sustainable nutrition strategy. Additionally, supplements can contain ingredients not listed on the label, due to poor regulation and quality control in these products. Supplementation, save for a targeted electrolyte replacement for extended workouts or hot days, is simply not necessary or ideal.

Benefits That Can Last a Lifetime

Youth athletes are a special population. While they carry many of the same basic nutritional needs as older athletes, their specific needs must balance optimized performance with developmental benchmarks. Societal and other pressures can also prime this group for eating disorders, but as a trusted fitness professional, you can help by providing guidance and/or referrals to qualified nutrition professionals to build sustainable and thoughtful nutrition plans for young athletes that are adaptable enough to meet immediate and long-term needs. The groundwork and guidance you provide, while remaining within scope and referring out when appropriate, can have lifelong effects on their well-being.