Nutrition in the Developing Athlete: Growth, Energy Availability, Recovery, Performance, and Emerging Epigenetic Considerations — A Narrative Review by Ori Scott M.Sc. Nutrition, RD.

Abstract

Background

Adolescence represents a period of rapid somatic growth, skeletal mineralization, endocrine maturation, neurocognitive development, and behavioral change. In young athletes, these developmental processes occur concurrently with the metabolic and mechanical demands of structured training and competition. Consequently, nutritional requirements cannot be derived simply by scaling adult sports-nutrition recommendations according to body mass. Inadequate energy or nutrient intake during this period may compromise growth, bone health, recovery, endocrine function, immune competence, psychological well-being, and athletic performance.

Objective

This narrative review critically synthesizes current evidence concerning nutrition in adolescent athletes, with particular emphasis on energy availability, Relative Energy Deficiency in Sport (RED-S), carbohydrate and protein requirements, dietary fat, micronutrients, hydration, recovery nutrition, supplementation, nutrition education, and the emerging relationship between nutrition, exercise, and epigenetic regulation.

Methods

A structured narrative-review approach was used. The literature framework was constructed around controlled vocabulary and concepts corresponding to relevant Medical Subject Headings (MeSH), including Adolescent, Athletes, Sports Nutritional Sciences, Exercise, Diet, Energy Metabolism, Carbohydrates, Dietary Proteins, Micronutrients, Iron, Calcium, Vitamin D, Water-Electrolyte Balance, Dietary Supplements, and Epigenesis, Genetic. Priority was given to PubMed/MEDLINE-indexed peer-reviewed studies, systematic and scoping reviews, consensus statements, and evidence syntheses represented in PubMed and Scopus-indexed literature. Particular weight was assigned to International Olympic Committee consensus work and contemporary literature addressing adolescent athletes. Evidence was interpreted hierarchically, distinguishing established sports-nutrition principles from emerging mechanistic or epigenetic hypotheses.

Results

Adequate energy availability is the foundation of nutrition for the developing athlete. Persistent or severe low energy availability may impair multiple physiological systems and contribute to RED-S in both female and male athletes. Carbohydrate requirements should be periodized according to training load rather than prescribed as a fixed daily percentage of energy intake. Protein should be consumed in sufficient total quantities and distributed across the day to support growth, tissue remodeling, and exercise recovery. Dietary fat remains essential for energy provision, essential fatty acids, fat-soluble vitamin absorption, cellular function, and endocrine physiology. Iron, calcium, and vitamin D require particular attention during adolescence because of rapid growth, bone accrual, and—in menstruating athletes—additional iron losses. Hydration strategies should be individualized according to exercise duration, environmental conditions, sweat losses, and opportunities to drink. Evidence does not support routine performance-supplement use in young athletes, and a food-first strategy remains appropriate. Nutrition education can improve knowledge, but knowledge alone does not reliably translate into sustained dietary behavior. Epigenetic research demonstrates biological interactions among diet, exercise, gene regulation, and metabolic adaptation; however, evidence is presently insufficient to justify epigenetic- or genotype-directed sports diets for adolescents.

Conclusion

Nutrition for adolescent athletes should simultaneously support growth, maturation, health, training adaptation, recovery, and performance. Prevention of problematic low energy availability should take precedence over aggressive manipulation of body mass or composition. Nutrition should be individualized according to biological maturation, sex, sport, training phase, training load, dietary pattern, environmental conditions, and clinical status. Current epigenetic findings are scientifically important but remain predominantly mechanistic and exploratory; they should not replace established nutrition principles in clinical or sports practice.

Keywords: adolescent athlete; youth sport; sports nutrition; energy availability; RED-S; growth; carbohydrate; protein; hydration; micronutrients; recovery; epigenetics.

1. Introduction

Adolescence is characterized by substantial changes in body size, body composition, skeletal architecture, endocrine physiology, brain development, and psychosocial function. For the adolescent athlete, these processes occur while additional energy and nutrients are required to support training, competition, tissue repair, and adaptation. Nutrition therefore serves several simultaneous biological functions: maintaining normal development, supporting health, supplying substrate for exercise, facilitating recovery, and enabling adaptation to training.

This distinction is fundamental because the adolescent athlete cannot appropriately be considered a smaller version of an adult athlete. Nutritional requirements are influenced not only by chronological age and body mass but also by biological maturation, sex, training volume, training intensity, sport characteristics, body-composition pressures, environmental conditions, dietary restrictions, and competition schedules.

Recent literature consistently emphasizes the need for individualized nutritional assessment in this population. Reviews of adolescent sports nutrition identify energy availability, carbohydrate intake, protein distribution, hydration, iron, calcium, vitamin D, and avoidance of unnecessary supplements as major practical priorities.

An additional area of scientific interest concerns epigenetic regulation. Exercise and nutritional exposures can influence DNA methylation, histone modification, non-coding RNA activity, and related regulatory pathways. These observations have generated interest in precision sports nutrition. Nevertheless, substantial differences exist between demonstrating molecular associations and establishing clinically useful dietary prescriptions. This distinction is particularly important in children and adolescents.

The purpose of this narrative review is therefore to integrate established sports-nutrition evidence with emerging molecular research while maintaining clear boundaries between evidence suitable for current practice and hypotheses requiring further investigation.

2. Literature Identification and Narrative-Review Methodology

This review was constructed as a structured narrative synthesis rather than a systematic review or meta-analysis. Accordingly, the objective was to integrate clinically and practically important evidence across multiple domains rather than estimate a single pooled intervention effect.

Search concepts were developed around the following domains:

1. adolescent/youth athletes;

2. growth and maturation;

3. sports nutrition;

4. energy requirements and energy availability;

5. RED-S;

6. carbohydrate availability;

7. dietary protein and exercise recovery;

8. dietary fat;

9. iron, calcium, vitamin D, and other micronutrients;

10. hydration and electrolytes;

11. dietary supplements and ergogenic aids;

12. nutrition education and dietary behavior; and

13. exercise, nutrition, genetics, and epigenetic regulation.

MeSH terminology was incorporated where applicable. Priority was assigned to peer-reviewed PubMed/MEDLINE-indexed evidence, systematic reviews, consensus statements, and contemporary reviews identified within PubMed/Scopus-based literature. Particular emphasis was placed on evidence directly involving adolescents rather than extrapolating exclusively from adult athletes.

The evidence was interpreted according to source hierarchy and directness. Consensus statements, systematic reviews, controlled investigations, and adolescent-specific studies were weighted more strongly than expert opinion. Where adolescent-specific experimental evidence was limited, extrapolation from adult sports-nutrition research was identified conceptually rather than presented as established pediatric evidence.

This distinction is particularly relevant for macronutrient periodization, supplementation, and epigenetics, for which direct evidence in adolescent athletes remains less extensive than evidence in adults.

3. The Developing Athlete Is Not a Small Adult

Growth itself represents an energetic and nutritional demand. Adolescence includes increases in height, lean mass, blood volume, organ mass, and skeletal mineral content, accompanied by substantial endocrine and metabolic changes.

Training introduces an additional requirement for substrate availability and tissue remodeling. Consequently, energy intake must cover basal physiological requirements, growth and maturation, normal daily activity, exercise expenditure, and recovery.

The practical consequence is that apparently adequate food intake can still be inadequate for an athlete whose training volume has increased substantially. Under-fueling may therefore occur without deliberate food restriction.

This phenomenon is particularly relevant during growth spurts, periods of intensified training, tournament schedules, multiple daily sessions, or participation in sports emphasizing leanness, weight categories, or aesthetic appearance.

4. Energy Availability: The Foundation of the Nutrition Strategy

Energy availability describes the amount of dietary energy remaining for physiological processes after the energetic cost of exercise has been considered.

Conceptually:

Energy Availability = (Energy Intake − Exercise Energy Expenditure) / Fat-Free Mass

Energy availability differs from conventional energy balance. An athlete can maintain a relatively stable body mass while experiencing physiological adaptation to inadequate energy availability.

Low energy availability may arise intentionally through restrictive eating or weight-control practices, or unintentionally when training volume increases without a corresponding increase in dietary intake. Appetite suppression, demanding school schedules, limited food availability, gastrointestinal discomfort around training, travel, and poor nutrition knowledge can further contribute.

For adolescent athletes, chronic under-fueling is particularly concerning because energy must simultaneously support athletic activity and biological development.

5. Low Energy Availability and RED-S

The International Olympic Committee describes RED-S as a syndrome involving impaired physiological and/or psychological functioning associated with exposure to problematic low energy availability.

Contemporary RED-S models extend substantially beyond the historical Female Athlete Triad. The condition can occur in female and male athletes and may affect reproductive function, skeletal health, metabolic regulation, immune function, gastrointestinal function, cardiovascular physiology, hematological status, psychological health, training response, and athletic performance.

Adolescence may represent a particularly vulnerable developmental window because inadequate energy availability can coincide with peak bone-mass acquisition and pubertal maturation.

Potential warning signs include persistent fatigue, impaired recovery, recurrent illness, declining performance, bone-stress injury, mood disturbance, restrictive eating, significant or unexplained body-mass changes, menstrual disturbances, and concerns regarding normal growth or pubertal development.

No single symptom establishes RED-S. Clinical evaluation should therefore integrate medical history, dietary assessment, training history, growth trajectory, menstrual and endocrine history when appropriate, injury history, psychological factors, and relevant laboratory or imaging investigations.

Importantly, menstrual dysfunction should not be considered a normal consequence of athletic training. Similarly, male athletes should not be assumed to be protected from the consequences of low energy availability.

6. Carbohydrate: Primary Exercise Fuel and a Periodized Nutrient

Carbohydrate is a major substrate for moderate- and high-intensity exercise and is particularly important for sports involving repeated high-intensity actions, prolonged activity, tournament play, or multiple training sessions.

Contemporary sports nutrition increasingly favors carbohydrate periodization rather than a single fixed carbohydrate prescription. Intake should therefore increase when training volume, intensity, or competition demands increase and may decrease during lower-load or recovery periods.

For young athletes, carbohydrate has an additional practical role: adequate carbohydrate intake can help prevent dietary protein from being disproportionately oxidized for energy.

Carbohydrate-rich foods should therefore be incorporated around demanding training sessions. Whole grains, rice, pasta, potatoes, cereals, fruit, dairy foods, legumes, and other nutrient-dense carbohydrate sources can contribute both exercise substrate and micronutrients.

During prolonged or demanding activity, carbohydrate-containing fluids or foods may become useful depending on exercise duration, intensity, environmental conditions, and gastrointestinal tolerance. These strategies should be practiced during training rather than introduced for the first time during important competition.

7. Protein, Growth, and Exercise Recovery

Protein provides amino acids required for normal growth, structural tissue development, enzymatic processes, immune function, and exercise-induced tissue remodeling.

Athletic protein requirements should not be considered solely as a question of total daily intake. Distribution and timing are also relevant. Protein consumed across several meals and snacks provides repeated opportunities for amino-acid availability throughout the day.

A food-first approach incorporating dairy products, eggs, fish, lean meat, poultry, legumes, soy foods, nuts, seeds, and appropriate combinations of plant proteins can generally provide adequate protein.

The recovery meal should not be reduced to protein alone. Effective recovery depends on adequate total energy, restoration of carbohydrate availability when required, protein for tissue remodeling, fluid and electrolyte replacement, micronutrient adequacy, and sufficient sleep.

The widespread belief that large quantities of protein automatically produce greater muscle development is therefore physiologically incomplete. Resistance and sport-specific training provide the adaptive stimulus; adequate energy and protein support the response.

8. Dietary Fat

Dietary fat is sometimes unnecessarily restricted in athletes attempting to reduce body mass or improve body composition.

This approach may be particularly inappropriate during adolescence. Fat contributes concentrated dietary energy, essential fatty acids, fat-soluble vitamin absorption, cellular membrane structure, and normal endocrine function.

Dietary quality should emphasize unsaturated fat sources such as nuts, seeds, vegetable oils, avocado, and fish while maintaining an overall varied dietary pattern.

Very-low-fat diets have no routine role in adolescent sports nutrition.

9. Micronutrients: Iron

Iron deserves particular consideration because it participates in hemoglobin synthesis, oxygen transport, mitochondrial metabolism, and numerous enzymatic reactions.

Risk of inadequate iron status may increase during periods of rapid growth and in athletes with menstrual blood losses, low energy intake, restricted diets, vegetarian or vegan eating patterns, or other sources of iron loss.

Iron-rich foods include meat and seafood where consumed, legumes, tofu, fortified foods, seeds, and selected vegetables. Vitamin C-containing foods can enhance absorption of non-heme iron.

Iron supplementation should not be prescribed simply because an athlete reports fatigue. Iron status requires appropriate clinical evaluation because fatigue has multiple causes and unnecessary iron supplementation carries potential risk.

10. Calcium, Vitamin D, and Skeletal Development

Adolescence is a critical period for bone-mass acquisition. Adequate energy availability, calcium, vitamin D, protein, and mechanical loading collectively contribute to skeletal development.

Calcium-rich foods include dairy products and appropriately fortified alternatives, as well as selected other foods depending on the dietary pattern.

Vitamin D status is influenced by dietary intake, supplementation where clinically indicated, ultraviolet exposure, season, latitude, skin pigmentation, and lifestyle.

Because RED-S and low energy availability can negatively affect skeletal health, calcium or vitamin D supplementation alone should not be viewed as a solution to an underlying energy deficiency.

Bone health requires an integrated approach that includes adequate energy availability, nutrient adequacy, appropriate loading, and endocrine health.

11. Hydration and Electrolytes

Hydration requirements vary substantially among athletes. Sweat rate is affected by body size, exercise intensity, environmental temperature, humidity, clothing and protective equipment, acclimatization, and individual physiology.

Young athletes should generally begin exercise adequately hydrated and have appropriate access to fluids during activity.

Water is suitable for many routine training sessions. Longer-duration, high-intensity, repeated, or hot-environment sessions may justify beverages containing carbohydrate and electrolytes.

Sweat sodium concentration varies markedly between individuals; consequently, a universal sodium prescription is inappropriate.

Post-exercise rehydration should consider both fluid and electrolyte losses, particularly when rapid recovery is necessary before another session.

Sports drinks should also be clearly distinguished from energy drinks. Energy drinks commonly contain substantial caffeine or other stimulants and are not equivalent to carbohydrate-electrolyte sports beverages. Their routine use is inappropriate for children and adolescents.

12. Nutrient Timing and Recovery

Nutrient timing should be understood as an extension of adequate daily nutrition rather than a substitute for it.

Pre-exercise nutrition should provide sufficient energy and carbohydrate while minimizing gastrointestinal discomfort. The exact meal size and timing depend on the interval before exercise and individual tolerance.

During prolonged exercise, fluid and carbohydrate availability may become increasingly important.

Following demanding exercise, nutrition should support restoration of glycogen, muscle remodeling, rehydration, and overall energy availability. Combining carbohydrate-containing foods with a high-quality protein source is a practical strategy when the next normal meal will not occur promptly.

When another demanding exercise session occurs within a short recovery interval, recovery nutrition becomes more time-sensitive.

For most adolescent athletes, however, consistency across the entire day remains more important than pursuing a narrowly defined “anabolic window.”

13. Female Adolescent Athletes: Menstrual and Reproductive Health

Menstrual health provides clinically relevant information concerning adolescent development and energy availability.

Delayed menarche, loss of established menstruation, or substantial changes in menstrual regularity warrant appropriate clinical evaluation rather than being automatically attributed to intensive training.

Menstruating athletes may additionally have increased vulnerability to iron deficiency, particularly when dietary intake is inadequate or menstrual blood loss is substantial.

Nutrition assessment in female athletes should therefore integrate energy availability, dietary quality, menstrual history, skeletal health, injury history, and iron status where clinically indicated.

14. Male Adolescent Athletes and RED-S

RED-S is not restricted to females.

Male athletes may develop low energy availability intentionally through weight-control strategies or unintentionally when training expenditure exceeds dietary intake.

Sports emphasizing endurance, leanness, weight categories, or high training volumes may create particular challenges, although RED-S can occur across sporting disciplines.

Potential manifestations include impaired recovery, recurrent injury, reduced performance, mood changes, altered endocrine function, and concerns regarding growth and maturation.

Research in male and adolescent populations remains less extensive than research in adult female athletes, reinforcing the need for sex- and maturation-specific investigations.

15. Dietary Supplements and Ergogenic Aids

The threshold for recommending supplements should be considerably higher in adolescent than adult athletes.

The majority of young athletes should prioritize adequate energy intake, food quality, carbohydrate availability, protein distribution, hydration, sleep, and recovery before considering performance supplements.

Supplements may also present contamination and anti-doping risks. A product being commercially available does not establish efficacy, purity, or safety.

Supplementation may nevertheless be clinically appropriate when a documented deficiency or other defined nutritional problem exists. Such decisions should be based on individualized assessment and professional supervision.

The evidence base therefore supports a food-first, supplement-only-when-justified model for young athletes.

16. Nutrition Knowledge, Education, and Behavior

Nutrition knowledge among adolescent athletes is highly variable.

A 2024 systematic review involving 32 studies and more than 4,500 adolescent athletes demonstrated substantial heterogeneity in nutrition-knowledge scores and identified important methodological limitations, including inconsistent and insufficiently validated questionnaires.

The literature also suggests that adolescent athletes frequently possess better general nutrition knowledge than sports-specific nutrition knowledge, with particularly important knowledge gaps concerning supplements.

Education can improve immediate nutrition knowledge. However, increased knowledge does not necessarily produce sustained changes in dietary intake, energy availability, or clinical outcomes.

More recent evidence therefore favors multicomponent interventions incorporating behavioral strategies and the athlete's broader social environment.

Parents, caregivers, coaches, schools, clubs, and the food environment may substantially influence what an adolescent athlete actually eats. Effective nutrition interventions should therefore move beyond simply providing information.

17. Nutrition, Exercise, and Epigenetic Regulation

Epigenetics describes regulatory processes capable of influencing gene expression without altering the underlying DNA sequence. Major mechanisms include DNA methylation, histone modifications, chromatin remodeling, and non-coding RNA regulation.

Exercise is capable of producing molecular responses involving metabolic, inflammatory, mitochondrial, and skeletal-muscle pathways. Nutrition can also interact with epigenetic processes through substrate availability, methyl-donor metabolism, fatty acids, polyphenols, vitamins, and other dietary exposures.

These mechanisms provide a biologically plausible interface through which environment, nutrition, and exercise may influence phenotype.

The concept is particularly interesting during childhood and adolescence because these are periods of substantial developmental plasticity.

Nevertheless, biological plausibility must not be confused with established clinical efficacy.

18. What Pediatric Epigenetic Evidence Currently Supports

Recent systematic evidence indicates that diet and combined diet-exercise interventions can be associated with measurable epigenetic changes in children and adolescents.

However, this literature is heterogeneous and has primarily investigated metabolic disease, obesity, insulin resistance, neurodevelopmental or other clinical conditions rather than athletic performance.

Similarly, contemporary exercise-nutrition epigenetic reviews describe associations involving DNA methylation, histone regulation, and non-coding RNA pathways, but characterize the evidence base as exploratory.

At present, there is insufficient evidence to prescribe a particular food, nutrient, supplement, or dietary pattern to an adolescent athlete for the purpose of inducing a specific performance-enhancing epigenetic modification.

Claims that individual foods can “activate athletic genes,” permanently improve athletic potential, or produce predictable performance adaptations through epigenetic manipulation substantially exceed the current evidence.

Epigenetics should therefore be considered an important research field rather than a current basis for routine precision nutrition in young athletes.

19. Practical Model: Grow, Learn, Train, Recover

A scientifically defensible model of adolescent sports nutrition can be summarized around four simultaneous objectives:

Grow: provide adequate energy, protein, essential fatty acids, calcium, vitamin D, iron, and other nutrients required for development.

Learn: maintain sufficient energy and nutrient availability for school performance, concentration, cognition, and psychological health.

Train: periodize carbohydrate, fluid, and total energy intake according to the demands of the training program.

Recover: provide adequate energy, carbohydrate, protein, fluid, micronutrients, and sleep to support adaptation and readiness for subsequent exercise.

Nutrition strategies that improve one domain at the expense of another—for example, reducing body mass while compromising growth or endocrine function—cannot be considered optimal performance nutrition.

20. Research Gaps

Several important limitations remain in the scientific literature.

First, adolescent-specific controlled feeding and longitudinal studies are considerably less common than adult sports-nutrition investigations.

Second, biological maturation is not consistently incorporated into study design despite its potential influence on energy requirements, body composition, and endocrine physiology.

Third, female athletes and some sport categories remain underrepresented.

Fourth, dietary intake and exercise energy expenditure are difficult to measure accurately in free-living adolescents, complicating estimates of energy availability.

Fifth, validated adolescent-specific screening and nutrition-knowledge instruments remain limited.

Sixth, long-term trials determining whether nutrition education changes actual energy availability, health, injury, and performance outcomes are required.

Finally, exercise-nutrition epigenetics requires substantially more longitudinal, tissue-specific, and adolescent-athlete-specific research before molecular observations can be translated into individualized dietary prescriptions.

21. Conclusions

Adolescent sports nutrition should be understood as developmental nutrition occurring within an athletic environment.

The primary nutritional objective is not simply maximizing immediate performance. It is to provide sufficient energy and nutrients to support normal growth, skeletal development, endocrine maturation, cognitive function, health, training adaptation, recovery, and sustainable athletic performance.

Adequate energy availability is central to this framework. Persistent problematic low energy availability can contribute to RED-S and affect athletes of both sexes. Prevention, early recognition, and appropriate multidisciplinary management are therefore essential.

Carbohydrate intake should reflect training demands, while adequate protein should be distributed throughout the day. Dietary fat should not be unnecessarily restricted. Iron, calcium, and vitamin D require particular consideration during adolescence, and hydration strategies should reflect individual and environmental conditions.

A food-first approach should remain standard. Routine ergogenic supplementation in young athletes is generally unsupported, and any supplementation should have a clearly defined rationale, professional oversight, and consideration of safety and anti-doping risk.

Nutrition education is valuable but should be integrated with behavioral, family, coaching, and environmental strategies rather than assuming that knowledge alone changes dietary behavior.

Finally, epigenetics provides an increasingly important framework for understanding interactions between exercise, nutrition, development, and gene regulation. However, current evidence does not support epigenetic-based diets or supplementation strategies for adolescent athletes. Until sufficiently rigorous athlete-specific research becomes available, established principles of adequate energy availability, dietary quality, training-specific fueling, recovery, hydration, and developmental health should remain the foundation of practice.

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Evidence-interpretation statement

Recommendations concerning energy availability, RED-S, carbohydrate, protein, hydration, skeletal nutrition, and iron are supported by established sports-nutrition and adolescent-health literature. Evidence concerning exercise- and nutrition-related epigenetic regulation is substantially less mature and should be considered hypothesis-generating rather than sufficiently validated for clinical prescription or performance-focused precision nutrition in adolescents.

Clinical and ethical statement

This review is intended for scientific and educational use. Individual adolescent athletes require assessment according to age, biological maturation, sex, sport, training load, dietary history, growth trajectory, medical history, injury history, menstrual/endocrine status when relevant, laboratory findings, psychological factors, and competition schedule. Restrictive diets, intentional dehydration, rapid weight manipulation, and unsupervised supplementation should not be routinely applied to developing athletes.