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A scoping review by Irwin et al. systematically mapped evidence on dietary intake, nutrition knowledge, behaviour, and intervention strategies in youth team sport athletes aged 12–19 years. While the findings are often interpreted through the lens of nutrition education and measurement limitations, they take on a broader meaning when viewed through Relative Energy Deficiency in Sport (RED-S).
Rather than simply describing “poor nutrition knowledge” or “suboptimal dietary intake,” the evidence begins to reflect a more complex reality: youth athletes operating in environments where energy availability is often inconsistent during a critical period of growth and development.
What the evidence base looks like
The review included 57 studies and 4,369 youth team sport athletes.
Key features of the literature:
- 59.6% cross-sectional designs
- Highly variable dietary assessment methods
- Limited adjustment for underreporting
- Low female representation (26.9%)
This creates a large but methodologically uneven evidence base.
What youth athletes are actually eating
Across studies, a consistent pattern appears:
Energy and carbohydrate intake
- Frequently reported below recommended levels
- Especially during heavy training and competition phases
However, objective methods (e.g. doubly labelled water) suggest that some of these deficits may be overestimated due to underreporting, meaning true intake is sometimes higher than reported.
Still, the direction of the trend remains consistent: energy intake often struggles to keep up with demand.
Protein, fat, and micronutrients
- Protein and fat intake: generally adequate
- Micronutrients: more consistently low
Common shortfalls:
- Vitamin D
- Calcium
- Iron
- Vitamins A and E
These nutrients are central to bone development, oxygen transport, immune function, and recovery in adolescence.
Nutrition knowledge: limited and not well measured
Nutrition knowledge is consistently reported as low, especially in sport-specific contexts.
However:
No validated nutrition knowledge tools exist for adolescent athletes in this literature.
So even this conclusion must be interpreted cautiously.
Education alone is not enough
Twelve intervention studies show a consistent pattern:
- Education-only approaches → minimal behaviour change
- Education + behaviour strategies → more reliable improvements
This reinforces that knowledge alone does not reliably translate into behaviour in youth sport environments.
What actually shapes eating behaviour
Only a small number of studies examined determinants, but findings were consistent.
Dietary intake is strongly shaped by:
- Parents
- Coaches
- Peers
- Environmental and logistical constraints (travel, timing, access to food, school–sport balance)
This means fuelling is not just an individual decision — it is heavily system-dependent.
What we also see in practice: the real-world challenge
Beyond the research, the applied reality in youth sport often highlights a different layer of complexity.
One of the most consistent challenges is not lack of interest or effort from parents — but uncertainty.
Many parents genuinely struggle with questions like:
- How much should my child actually be eating for their training load?
- What foods should I be buying that are practical, affordable, and appropriate?
- When should I be giving food around training so it doesn’t upset their stomach?
- What do I do when my child feels sick, nauseous, or unable to eat after intense training?
This uncertainty becomes even more pronounced in multisport athletes with back-to-back training sessions, early mornings, school commitments, and evening sessions.
In practice, we often see situations where:
- Athletes go into training under-fuelled because the day has been busy
- Post-training appetite is suppressed, leading to missed recovery nutrition
- Parents are unsure whether to push food immediately or wait until symptoms settle
- Convenience becomes the deciding factor rather than structured fuelling
As a result, quick, accessible options often become part of the solution — including practical fuel sources like RED-SCUE energy bars, which parents may use as a simple way to bridge gaps between meals, training, and travel.
This isn’t about “optimal sports nutrition strategy” in an elite sense. It reflects something more fundamental: trying to consistently meet energy demands in real life conditions where time, appetite, and logistics don’t always align.
Reframing through RED-S: what the evidence suggests
Although Irwin et al. do not explicitly discuss RED-S, their findings can be interpreted through a low energy availability lens.
Energy intake and LEA risk
Repeated reports of low energy and carbohydrate intake during high training periods align with conditions associated with low energy availability (LEA).
In adolescents, this matters because energy is required for:
- Training adaptation
- Daily functioning
- Growth and maturation
- Bone development
Even short-term mismatches may be more impactful in this population than in adults.
Multisport athletes and fluctuating demand
Many youth athletes participate in multiple sports or overlapping seasons, leading to:
- Variable weekly training loads
- Inconsistent fueling opportunities
- Travel-related disruption
- Uneven recovery nutrition
This creates cycles of energy imbalance across the week, rather than a steady pattern of intake.
Micronutrients and long-term development
Micronutrient shortfalls carry added importance in adolescence:
- Calcium + vitamin D → bone health and skeletal development
- Iron → oxygen transport and fatigue resistance
- Vitamins A and E → immune and cellular function
These are not just performance nutrients — they influence long-term health trajectories.
Knowledge is not the primary driver
Despite limited nutrition knowledge, behaviour change is not strongly driven by education alone.
Instead, intake is shaped by:
- Environmental constraints
- Social influences
- Practical food access and timing
This aligns with RED-S principles: energy availability is structural and behavioural, not purely cognitive.
Behavioural approaches are more effective
Interventions combining education with behaviour change strategies are more effective because they:
- Make fuelling more accessible
- Build habits into training environments
- Reduce reliance on individual decision-making alone
Integrated interpretation
Across 57 studies and 4,369 athletes, the evidence consistently shows:
- Frequent low energy and carbohydrate intake
- Recurrent micronutrient inadequacies
- Poorly measured nutrition knowledge
- Strong environmental and social influence on eating
- Methodological limitations and variability
- Underrepresentation of female athletes (26.9%)
Taken together, and viewed through a RED-S lens, this describes a system where youth athletes may be exposed to unintentional underfuelling shaped by environmental, logistical, and social constraints during a critical developmental period.
This does not confirm RED-S or allow prevalence estimates. Instead, it highlights a consistent risk architecture:
- High and fluctuating energy demands
- Inconsistent intake patterns
- Environmental and logistical barriers
- Socially mediated eating behaviours
- Measurement uncertainty
Final takeaway
Youth team sport athletes are not simply “under-informed eaters.” They are operating in real-world systems where training demands, growth, appetite, time pressure, and parental uncertainty all interact to influence fuelling.
Rather than a knowledge deficit alone, the evidence points toward a broader structural issue — where adolescents may be at risk of low energy availability due to the realities of sport, school, and everyday life.
