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The Consequences of Undereating for Young Athletes

The Consequences of Undereating for Young Athletes

Athlete health is extremely important. The female athlete triad is a concept related to reduced health and performance in female athletes of virtually any age. The relative energy deficiency in sport (RED-S) considers the fact that males can be affected, too. Here, we explain the consequences of undereating for young athletes.

The Female Athlete Triad

This is made up of three different areas - low energy availability (not eating enough), menstrual dysfunction, and a low bone mineral density (Desbrow et al., 2014). Eating enough is therefore vital for adolescent female athletes (those going through puberty, particularly teenagers). This is often seen in sports with a weight category and/or where aesthetics (looking lean) is potentially important. Undereating can happen with or without an eating disorder, with or without intending to. There are significant long-term consequences to suffering from these three parts of the triad, as explained by Thein-Nissenbaum in 2013. Disordered eating has been associated with low energy availability, shutting down the reproductive and skeletal systems in your body. Menstrual disturbances are associated with low oestrogen (a female reproductive hormone), which affects bone development. Reduced bone development during adolescence is not usually reversed, showing how these effects can last into adulthood and beyond. Signs and symptoms include rapid weight loss, restrictive eating or fasting, and use of diet pills; cessation of menstruation in a eumenorrheic female (losing your period); and slow-healing stress fractures and overuse injuries (Thein-Nissenbaum & Hammer, 2017). Detailed examinations should be undertaken for any female with a history of altered eating behaviours, menstrual irregularity, stress fracture(s) or prolonged musculoskeletal injury should. Treatment strategies include nutrition counselling, diet modification, addressing menstrual dysfunction and weightbearing exercise e.g. running and strength training.

Consequences of the Female Athlete Triad flow chart. Thein-Nissenbaum, J. (2013)

Consequences of the Female Athlete Triad flow chart. Thein-Nissenbaum, J. (2013)

Relative Energy Deficiency in Sport (RED-S)

RED-S is seen as a ‘syndrome’. This refers to impaired physiological function including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis, and cardiovascular health caused by relative energy deficiency (Mountjoy et al., 2014). This ‘energy deficiency’ is relative to the balance between dietary energy intake and expenditure (i.e., how much energy you use) required for health and activities of daily living, growth and sporting activities. Essentially, eating LESS than you need can have serious consequences whether you’re male or female! Recent research suggests male athletes, especially those in sports emphasising leanness (again), may experience similar negative health consequences to the female athlete triad from being active and playing sport (Tenforde et al., 2016). The International Olympic Committee (Muntjoy et al., 2014)explains how RED-S is bad for performance. Long-term low energy availability may develop nutrient deficiencies (including anaemia – low iron levels), chronic fatigue and increased risk of infections and illnesses, all of harm health and performance. Recommendations have therefore been made, for example:

  • Educational programmes on RED-S, healthy eating, nutrition, energy availability, the risks of dieting and how these affect health and performance.
  • Reduction of emphasis on weight, emphasising nutrition and health to enhance performance.
  • Development of realistic and health-promoting goals related to weight and body composition. 

Mountjoy et al. (2014) explain the potential performance effects of RED-S. 

Mountjoy et al. (2014) explain the potential performance effects of RED-S.

Listen to your body. Look after yourself and other athletes. Always consult a fully qualified doctor and dietitian in such situations. Here’s to best health and performance!

Need more support?

At Youth Sport Nutrition we've developed a free app to help youth athletes find quick, easy, cheap, and tasty meal ideas. You can download it from your app store today, just search YSN Kitchen App (or click here). If you want any help with designing a food-first meal plan to help build your youth athlete up, speak to our nutrition team today.

YSN have developed a range of products that comprise of whole food ingredients, carefully selected to aid young athlete’s needs, taste great and add convenience to a busy schedule with calorie intakes at the forefront of formulation. The powdered formulas enable quick solubility in water or milk, to form a delicious nutrient packed food powdered shake that you can enjoyed pre or post exercise- helping aid recovery and increase energy.

Youth Sport Nutrition always recommended to opt for whole foods first, with food powders such as NUTRI-TEEN shake and energy bars such as NUTRI-TEEN bars a nutrient packed way to top-up on high-quality nutrients, designed to support those youth athletes faced with a tight schedule.

Author: Liam Oliver (edited further by YSN)

Disclaimer: This article is intended to provide general information about nutrition for youth athletes and is not meant to replace professional dietary advice or individual nutritional counselling. Every child's nutritional needs can vary due to factors such as age, size, physical activity level, and medical conditions. We strongly recommend consulting with a registered dietitian or a healthcare provider before making changes to your child's diet, such as adding food powders. YSN and the author of this article do not take responsibility for any possible consequences from any treatment, procedure, dietary modification, action, or application of medication which results from reading or following the information contained in this article.


Desbrow, B., Mccormack, J., Burke, L., Cox, G., Fallon, K., Hislop, M., ... Leveritt, M. (2014). Sports Dietitians Australia position statement: Sports nutrition for the adolescent athlete. International Journal of Sport Nutrition and Exercise Metabolism, 24(5), 570-84.

Mountjoy, M., Sundgot-Borgen, J., Burke, L., Carter, S., Constantini, N., Lebrun, C., ... & Ljungqvist, A. (2014). The IOC consensus statement: beyond the female athlete triad—Relative Energy Deficiency in Sport (RED-S). Br J Sports Med, 48(7), 491-497.

Statuta, S., Asif, I., & Drezner, J. (2017). Relative energy deficiency in sport (RED-S). British Journal of Sports Medicine, 51(21), 1570.

Tenforde, A. S., Barrack, M. T., Nattiv, A., & Fredericson, M. (2016). Parallels with the female athlete triad in male athletes. Sports Medicine, 46(2), 171-182.

Thein-Nissenbaum, J. (2013). Long term consequences of the female athlete triad. Maturitas, 75(2), 107-112.

Thein-Nissenbaum, J., & Hammer, E. (2017). Treatment strategies for the female athlete triad in the adolescent athlete: Current perspectives. Open Access Journal of Sports Medicine, 8, 85-95.

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