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Nutrition: Eating More v. Eating Less

nata Yonkoski
Feb 16, 2025By nata Yonkoski


In lean sports like distance running, dance, and cycling, and gymnastics, maintaining a lower body weight is often emphasized. However, eating too little can backfire, leading to fatigue, muscle loss, hormonal imbalances, and increased injury risk. Many athletes think that eating less will make them lighter and faster, but in reality, it can decrease endurance, weaken muscles, and slow recovery.

Research shows that low energy availability (LEA) impacts key functions like oxygen transport, muscle repair, and bone health, ultimately hurting long-term performance. This section breaks down exactly how underfueling affects lean-sport athletes and why strategic fueling is the key to success.

Impact of Eating Less on Lean-Sport Athletes

  • Nutrient Deficiencies & Oxygen Transport: Restrictive diets in athleetes in lean-sports (distance running, dance, swimming, judo, diving, biking, etc.) can lead to nutrient deficiencies, particularly iron deficiency, which is one of the most common in endurance athletes.
    • Example: If a female distance runner follows a diet that cuts out red meat and iron-rich foods (e.g., spinach, lentils, fortified cereals), she risks low iron stores, making it harder for her blood to carry oxygen to working muscles. This can lead to early fatigue, breathlessness, and decreased endurance.
    • Real Study Insight: Research from the Journal of Sports Medicine (Sim et al., 2019) found that iron-deficient runners exhibited a 15% decrease in VO₂ max (a key measure of aerobic fitness), directly impairing their ability to sustain long distances.
  •  Catabolism & Muscle Breakdown: When athletes don’t eat enough, their bodies enter a catabolic state, meaning they break down muscle tissue for energyinstead of using carbohydrates or fats.
    • Example: A competitive swimmer who trains 6 days a week but eats too little will experience muscle loss rather than growth, leading to weaker strokes and slower race times over the season.
  • Metabolic & Hormonal Disruptions: Eating too little can suppress thyroid hormones (which regulate metabolism) and leptin (which controls hunger and energy balance).
    • Example: A high school gymnast who restricts calories to maintain a certain weight may feel constantly fatigued, cold, and sluggish, as her thyroid hormone production slows down to conserve energy.
    • Study Insight: A 2022 study in the European Journal of Applied Physiology (Hammond et al.) found that low energy availability in female athletes leads to irregular menstrual cycles, slower metabolism, and increased risk of stress fractures due to hormonal imbalances.
  • Bone Health & Stress Fractures: Athletes with low energy intake often experience lower bone mineral density, increasing their risk of stress fractures.
    • Example: A track athlete who significantly restricts her diet may develop shin splints that turn into a stress fracture, forcing her to take months off from training.
  •  Cognitive Function & Mental Performance: Eating too little can reduce brain function, affecting reaction time, focus, and decision-making.
    • Example: A soccer player who doesn’t eat enough carbohydrates before a game may struggle with quick decision-making on the field and experience slower reaction times when trying to intercept passes.
    • Study Insight: A Harvard Medical School review (2021) noted that low glucose availability impairs cognitive function, making it harder to concentrate, strategize, and react quickly—all critical in competitive sports.



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Athletes in power-based sports like football, basketball, weightlifting, wrestling, and sprinting rely on explosive strength, speed, and muscle power. These sports demand fast-twitch muscle activation, high-intensity effort, and rapid recovery between sessions. However, not eating enough can severely weaken performance by slowing muscle repair, reducing strength, and increasing injury risk.

Unlike endurance athletes, power and strength athletes require more energy to sustain muscle mass and perform explosive movements. Underfueling can lead to decreased force production, longer recovery times, and even muscle breakdown as the body turns to muscle tissue for energy.


Impact of Eating Less on Power & Strength Athletes  

  • Muscle Damage & Recovery Demands: Athletes in power-based sports (e.g., football, basketball, weightlifting, wrestling, sprinting) rely heavily on fast-twitch muscle fibers, which require high oxygen availability and rapid energy turnover for explosive movements.
    • Example: A football player or weightlifter who is iron-deficient may experience sluggishness, reduced strength, and slower reaction times, affecting their ability to sprint, tackle, or lift heavy loads effectively.
    • Research Insight: According to a 2022 study in the Journal of Strength and Conditioning Research (Smith et al.), power athletes with low iron levels experienced 10–15% decreased muscle power output and slower recovery post-training.
  • Impact Forces: Iron Loss in Contact and High-Impact Sports: Athletes in high-impact or contact sports like basketball, football, rugby, and martial arts are susceptible to iron loss through repetitive impact forces. This includes foot strike hemolysis (red blood cell breakdown from running and jumping) and internal bruising from collisions.
    • Example: A basketball player who jumps repeatedly or a wrestler engaging in high-contact takedowns may experience fatigue and decreased endurance over time due to iron depletion caused by impact stress.
    • Research Insight: A study in the Journal of Sports Medicine (Gonzalez et al., 2021) found that contact sport athletes had higher markers of hemolysis and iron loss, increasing their risk of performance decline if iron intake was not sufficient.


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Impact of Overeating on Athletes

  • Digestive Discomfort: Consuming large meals, especially those high in fiber or fat, shortly before exercise can lead to gastrointestinal (GI) distress. Symptoms such as bloating, cramping, and nausea are common.
    • Example: A swimmer who eats a high-fiber meal (brussel prouts, pears, almonds, lentils, etc.) 20 minutes before a race may experience stomach cramps and bloating in the pool, hindering their performance.
  • Decreased Efficiency: Excessive calorie intake, particularly from unhealthy sources, can lead to weight gain, increasing the energy cost of movement and reducing overall efficiency.
    • Example: A basketball player who frequently consumes high-calorie fast food (McDonalds, Arby's, Chick-Fil-A) may gain weight, leading to decreased speed and agility on the court.
  • Sluggishness and Energy Crashes: Overconsumption of simple sugars can cause rapid spikes in blood glucose levels, followed by sharp declines, leading to feelings of fatigue and decreased stamina.
    • Example: A tennis player who consumes sugary snacks during breaks may experience an initial energy boost, followed by a sudden drop in energy, affecting their performance in later sets.
  • Reduced Power-to-Weight Ratio: In sports requiring explosive movements, maintaining an optimal power-to-weight ratio is essential. Excess body weight from overeating can diminish this ratio, impairing performance.
    • Example: A weightlifter who gains unnecessary body fat may find it more challenging to lift weights relative to their body mass, reducing their competitive edge.
  • Decreased Agility: Additional body weight can impede an athlete's ability to make quick directional changes, essential in many sports.
    • Example: A soccer midfielder carrying extra weight may struggle with rapid pivots and sprints, affecting their effectiveness on the field.
  • Slower Recovery: Overeating, especially without proper nutrient balance, can impair recovery processes, leading to prolonged fatigue and increased injury risk.
    • Example: A swimmer indulging in high-fat, low-carbohydrate meals post-training may experience delayed muscle glycogen replenishment, resulting in slower recovery times.
    • Research Insight: A study in the Journal of Sports Science & Medicine found that inadequate energy intake is associated with increased systemic stress and impaired recovery in athletes.
  • Energy Mismanagement: Consuming excessive simple carbohydrates before exercise can lead to rapid energy fluctuations, adversely affecting performance during high-intensity activities.
    • Example: A sprinter who consumes a large amount of candy before a race may experience an initial surge in energy, followed by a precipitous drop, compromising their performance.

In summary, athletes should strive for a balanced diet tailored to their specific sport and individual needs. Proper nutrition ensures optimal performance, efficient recovery, and overall well-being. 


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Final Takeaway: Balanced Nutrition is Key
Both eating too little and eating too much can negatively impact an athlete’s performance, recovery, and long-term health. To make you feel the best whether it's during a game, you're practicing your sport, or walking around throughout the day, you need to balance your nutrition. That being said, what works for one person may not work for the other. It is up to you to balance your nutrition, ensuring enough fuel for energy while avoiding unnecessary weight gain, sluggishness, or nutrient deficiencies.

📌 Key Actionable Steps:
✅ Prioritize iron-rich foods like lean meats, spinach, and fortified grains
✅ Choose complex carbs for sustained energy
✅ Monitor energy intake vs. training demands to prevent underfueling or overeating
✅ Seek professional guidance if struggling with nutrition, weight, or energy levels



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