Optimising nutrition – girls and women in sports

This blog by performance nutritionist Faye Townsend explores essential topics in female athlete nutrition, focusing on hormonal factors, energy availability, and personalised strategies for performance and recovery. It also offers practical tips for optimising health and athletic success.

Introduction

Women’s participation in sports has surged, with their representation in the Olympics increasing from 26% in 1988 to 50% in 2024¹. As women continue to break new ground, are we fully addressing their unique nutritional needs?

Despite our growing understanding, female athletes are often treated as “smaller men.” This blog explores how hormonal fluctuations, energy availability, and nutrient intake specifically affect their performance and health, raising awareness and offering strategies to support female athletes effectively.

What are the challenges women face?

Most sports nutrition advice is tailored to male athletes, leaving women with guidelines that may not suit their needs. Only 6% of sports science research from 2014 to 2020 focused exclusively on women¹. This gap results in generalised advice that can overlook critical issues like menstrual irregularities and low bone density. For many grassroots female athletes, the lack of access to coaching and nutritional guidance exacerbates these challenges.

Why are women different from men?

Ovarian hormonal fluctuations are a primary factor influencing women’s nutrition and performance. Unlike men, who have relatively stable hormone levels, women experience variable shifts in hormones throughout their menstrual cycles, with hormonal contraceptives, and during pregnancy and menopause. These dynamic changes are crucial for understanding how these different profiles affect nutrition, training, and performance. As we increasingly recognise their impact, it’s clear this is a vital area for further research in women’s sports.

What role do estrogen and progesterone play on performance?

Estrogen and progesterone, while primarily reproductive hormones, influence multiple physiological systems including cardiovascular, metabolic, respiratory, and nervous systems². Estrogen may enhance muscle strength, bone density, and glycogen metabolism, while progesterone often acts antagonistically. However, conflicting evidence exists, and much of the research is animal-based, indicating a need for more studies in women.

When in the menstrual cycle are its effects most noticeable?

A survey of Australian Olympic and Paralympic athletes revealed that 65.6% believed their menstrual cycle impacted performance, with common symptoms including pain (83%), bloating (78%), and low energy (70%)³. Many athletes preferred to compete just after their period. The meta-analysis by McNulty et al.⁴, found that the early follicular phase might influence performance, but results vary widely and are often based on low-quality studies.

What are the key nutritional priorities for female athletes?

Figure 1: Potential hierarchy of nutritional considerations and needs for female athletes. Taken from Holtzman, 2021.⁵

Practical Tip: Follow a hierarchical approach to nutrition⁵. Begin by ensuring adequate energy availability and hydration. Address macronutrient and micronutrient needs before focusing on menstrual cycle-specific adjustments. Prioritise energy and sport-specific nutrition before delving into more detailed cycle-based changes. There’s no point tailoring based on menstrual phase unless you’ve built the foundations first.

What happens when nutrition goes wrong?

Challenges such as unintentional undereating, limited nutritional knowledge, food insecurity, and eating disorders are common among female athletes, particularly in endurance, aesthetic, and weight-class sports. The 2023 International Olympic Committee report estimates that Low Energy Availability (LEA) and Relative Energy Deficiency in Sport (RED-S) affect 23% to 79.5% of female athletes⁶.

Low Energy Availability occurs when there is a discrepancy between the energy an athlete consumes and the energy expended through exercise, leaving insufficient energy to support essential bodily functions. This leads to a range of health and performance issues collectively known as Relative Energy Deficiency in Sport (RED-S).⁶

The effects of RED-S are profound and widespread. It can diminish performance, disrupt menstrual cycles, weaken bones, increase the risk of injuries, and lead to mental health issues like depression and anxiety as shown in the figures below. Many of these disruptions occur when energy availability drops below 30 kilocalories per kilogram of fat-free mass per day, this is why this threshold has historically been used to identify low energy availability.

Figure 2 and 3. REDS. Taken from Mountjoy et al. 2023⁶

Practical Tip: It’s essential for coaches, Sports Nutritionist, support staff and athletes to focus on health and performance rather than appearance, ensuring that energy intake is sufficient to support both daily activities and performance. Promoting a positive relationship with food and emphasising the importance of fuelling the body properly is key to avoiding these risks.  If you spot red flags, refer to a sports medical professional specialising in Relative Energy Deficiency in Sport.

How does nutrition impact performance and training?

Nutrition is essential for supplying the energy we need not just for daily activities, but also for effective performance, training, and recovery. It also influences body composition, bone health, mood, motivation, and the risk of illness and injury.

Are females hitting the target when it comes to carbohydrates?

Carbohydrates are widely recognised as the key fuel during moderate to high intensity exercise, yet many female athletes in various sports do not meet recommended carbohydrate levels⁷. Recommendations for carbohydrate intake can be found in Burke and colleagues⁸ . But why are females failing to meet these recommendations?  Several factors may contribute to this issue:

• Favouring low-calorie, nutrient-dense foods like fruits and vegetables
• Concerns about body weight and composition
• Choosing low-calorie sweeteners over sports drinks during high-intensity exercise
• Limited understanding of the importance of carbohydrates
• Negative attitudes towards carbohydrates fuelled by social media

Inadequate carbohydrate consumption over time can lead to:

• Early fatigue during physical activity
• Decreased performance in high-intensity efforts
• Cognitive issues, such as poor concentration and diminished alertness
• Ineffective recovery between exercise sessions
• Relative Energy Deficiency in Sport

Should carbohydrate intake vary by menstrual cycle phase?

There’s ongoing debate about whether female athletes should adjust their carbohydrate intake based on menstrual cycle phases. Although some research points to reduced glycogen storage during the follicular phase compared to the mid-luteal phase, there is not enough strong evidence to warrant major changes in carbohydrate intake⁹. Ensuring overall daily carbohydrate needs are met is likely sufficient to support optimal performance, regardless of menstrual cycle fluctuations.

What are the recommendations for protein?

Minimal research has explored the endogenous and exogenous hormonal effects on the protein needs of female athletes. However, the 2023 International Society of Sports Nutrition Position Stand¹⁰shared some key protein considerations for female athletes:

• Pre-menopausal and oral contraceptive athletes should consume 0.32–0.38g of high-quality protein per kg body weight post-exercise for muscle repair.
• Peri- and post-menopausal athletes should aim for 6–10g of essential amino acids (EAA) as close to end of exercise as possible to counteract anabolic resistance.
• For all women, of all phases, daily protein intake should fall within 1.8–2.2g per kg, with a consideration of a 12% increase recommended for athletes in the luteal phase.
• Consume 0.3g of protein per kg body weight every 3 hours for optimal recovery during extended periods.
• Pre-sleep protein may help reduce soreness and improve recovery in athletes with low energy availability.

Which micronutrient should females keep in mind?

Micronutrients are crucial for health and performance, though needed in smaller amounts. Females, in particular, may face high risk of deficiencies in iron, calcium, and vitamin D due to factors like menstrual losses, inadequate energy availability, and exercise-induced changes. Unlike other areas of sports nutrition research, iron, calcium, and vitamin D supplementation, females are well represented in the literature (71%)¹¹. You can find an overview of key consideration from Gatorade Sports Science Institute (2023) here.

Iron:

Importance: Vital for oxygen transport and energy.

Risk: Higher risk of deficiency in females due to menstrual losses (5-40 mg per cycle) and reduced absorption linked to exercise-induced fluctuations in hepcidin^12,13.

Recommended Intake: 18 mg/day for females vs. 8 mg/day for males; athletes may need more.

Screening: Regular iron deficiency screening every 6 months, with more frequent checks for those with known iron issues, low energy availability, special diets, or menstrual disturbances.

Absorption: Enhance absorption by monitoring heme iron intake and combining iron-rich foods with Vitamin C.

Calcium:

Importance: A major bone forming mineral. : Especially important for amenorrheic athletes who are at higher risk for stress fractures¹⁴.

Recommendations: Females aged 19-50 are advised to consume 1000 mg of calcium daily. For those aged 51 and older, the recommendation increases to 1300 mg. Amenorrheic athletes and other high-risk groups should aim for 1500 mg daily, according to the International Olympic Committee¹⁵.

Impact of Exercise: Intense exercise can cause calcium loss through sweat, potentially leading to bone breakdown if intake is inadequate¹⁶.

Vitamin D:

Importance: Key for muscle function, immunity, and bone health by enhancing calcium absorption and bone mineralisation. Additionally, vitamin D impacts estrogen production, which affects bone health and menstrual status¹⁷.

Risk: Athletes with low vitamin D levels face a higher risk of stress fractures¹⁸.

Sources: Adequate sun exposure and dietary intake are important.

Supplementation: 2000-4000 IU/day may be necessary for those with deficiencies¹⁹.

Why is bone health important in female athletes?

Bone stress injuries are 2-4 times more common in females than males, affecting up to 20% of female athletes²⁰. These injuries are often linked to reduced bone mineral density²¹. Low bone density can lead to serious issues, such as a higher risk of developing osteoporosis early in life²². Additionally, cutting back on carbohydrates around training can immediately affect bone health by increasing bone breakdown²³. Just 4-5 days of low energy availability can disrupt important hormonal pathways and bone remodeling markers²⁴. Therefore, taking proactive steps to support bone health is essential for a female athlete’s overall well-being and performance

Call to Action:

Let’s start conversations, educate, and support female athletes in overcoming the unique challenges they face. When appropriate, collaborate with them to adjust nutrition and training based on their body’s feedback and the latest research. This approach will help cultivate a healthier, stronger, and more empowered generation of female athletes.

Additional Resources

• Mountjoy M, Sundgot-Borgen J, Burke L, et al. The IOC consensus statement: Beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S). Br J Sports Med. 2018;52(11):687-697. doi:10.1136/bjsports-2018-099193.
• Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee’s (IOC) consensus statement on relative energy deficiency in sport (RED-S). Br J Sports Med. 2023;57(17):1073-1097. doi:10.1136/bjsports-2023-105679.
• No Period Now What. Available at: https://www.noperiodnowwhat.com/. Accessed August 29, 2024.
• International Olympic Committee. Relative Energy Deficiency in Sport (RED-S): Consensus Statement. Available at: https://stillmed.olympics.com/media/Documents/Athletes/Medical-Scientific/Consensus-Statements/REDs/IOC-REDs-CAT-V2.pdf. Accessed August 29, 2024.
• Warren M, Goodman A, Williams D, et al. Relative energy deficiency in sport (RED-S): A review and update. J Sports Sci. 2022;40(1):1-17. doi:10.1177/17479541211054458.
• Project REDs Toolkit. Available at: https://www.canva.com/design/DAF1doaytrw/uNZmebC3IO1uHLVb9wDRzQ/view?utm_content=DAF1doaytrw&utm_campaign=designshare&utm_medium=link&utm_source=editor. Accessed August 29, 2024.
• Keay N, Francis G. Infographic. Energy availability: concept, control and consequences in relative energy deficiency in sport (RED-S). Br J Sports Med. 2019;53(20):1310-1311. doi:10.1136/bjsports-2019-100683

Experts to follow:

• Dr Nicky Keay @drnickykeay
• Dr Amal @sportsexercise_dr_amal
• Renee Mcgenor @r_mcgregor
• Kelly McNulty @periodoftheperiod
• Dr Hazel Walace @thefoodmedic
• Alyssa Olenick @doclyssfitness
• Sam Moore @sammoorestrong

Books:

• McKay S. Invisible women: Exposing data bias in a world designed for men. London, UK: Vintage Publishing; 2021.
• McKay S. Demystifying the female brain: A neuroscientist explores health, hormones and happiness. London, UK: Hachette; 2022.
• Wallace H. The Female Factor: Making women’s health count. London, UK: Vermilion; 2022.
• Kaye P. The M Word: Everything you need to know about menopause. London, UK: Vermilion; 2021.
• McGregor R. The Female Athlete Training Diary. Available at: https://reneemcgregor.com/product/the-female-athlete-training-diary/. Accessed August 30, 2024.

Disclaimer: This blog has been developed in association with the healthcare professional support team at GetPro Professional. Approval of each sponsor and activity is carefully assessed for suitability on a case by case basis. Sponsorship does not imply any endorsement of the brand by MyNutriWeb, its organisers, its moderators or any participating healthcare professional, or their association. Sponsorship funds are reinvested into the creation and promotion of professional development opportunities on MyNutriWeb.

List of References

^[1]Cowley ES, Olenick AA, McNulty KL, Ross EZ. “Invisible sportswomen”: The sex data gap in sport and exercise science research. Women Sport Phys Activ J. 2021;29(2):146-151.

^[2] Bernstein C, Behringer M. Mechanisms underlying menstrual cycle effects on exercise performance: A scoping review. Women Sport Phys Act J. 2023;31(2):129-146.

^[3] McNamara A, Harris R, Minahan C. ‘That time of the month’… for the biggest event of your career! Perception of menstrual cycle on performance of Australian athletes training for the 2020 Olympic and Paralympic Games. BMJ Open Sport Exerc Med. 2022;8(2)
. doi:10.1136/bmjsem-2021-001300.

^[4] McNulty KL, Elliott-Sale KJ, Dolan E, et al. The effects of menstrual cycle phase on exercise performance in eumenorrheic women: A systematic review and meta-analysis. Sports Med. 2020;50:1813-1827. doi:10.1007/s40279-020-01354-4.

[5] Holtzman, B., & Ackerman, K. E. (2021). Recommendations and nutritional considerations for female athletes: Health and performance. Sports Medicine, 51(Suppl 1), 43–57.

^[6] Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee’s (IOC) consensus statement on relative energy deficiency in sport (RED-S). Br J Sports Med. 2023;57(17):1073-1097. doi:10.1136/bjsports-2023-105679.

[7] Dasa MS, Friborg O, Kristoffersen M, et al. Energy expenditure, dietary intake and energy availability in female professional football players. BMJ Open Sport Exerc Med. 2023;9

[8]Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for training and competition. In: Burke LM, Deakin V, eds. Food, Nutrition and Sports Performance III. Routledge; 2013:17-27.

[9] Oosthuyse T, Bosch AN. The effect of the menstrual cycle on exercise metabolism: implications for exercise performance in eumenorrhoeic women. Sports Med. 2010;40(3):207-227.

^[10] Sims ST, Kerksick CM, Smith-Ryan AE, Janse de Jonge X, Hirsch KR, Arent SM, Antonio J. International Society of Sports Nutrition position stand: Nutritional concerns of the female athlete. J Int Soc Sports Nutr. 2023;20(1):2204066.

[11] Smith SE, et al. Managing female athlete health: auditing the representation of female versus male participants among research in supplements to manage diagnosed micronutrient issues. Nutrients. 2022.

^[12] Harvey LJ, Armah CN, Dainty JR, et al. Impact of menstrual blood loss and diet on iron deficiency among women in the UK. Br J Nutr. 2005;94(4):557-564.

^[13] Peeling P, Dawson B, Goodman C, Landers G, Trinder D. Athletic induced iron deficiency: new insights into the role of inflammation, cytokines and hormones. Eur J Appl Physiol. 2008;103(4):381-391.

^[14] Heikura IA, Uusitalo AL, Stellingwerff T, et al. Low energy availability is difficult to assess but outcomes have large impact on bone injury rates in elite distance athletes. Int J Sport Nutr Exerc Metab. 2018;28(4):403-411.

^[15]Mountjoy M, Sundgot-Borgen J, Burke L, et al. The IOC consensus statement: beyond the female athlete triad—Relative Energy Deficiency in Sport (RED-S). Br J Sports Med. 2014;48(7):491-497

^[16] Rowe P, Koller A, Sharma S. Physiology, bone remodeling. In: StatPearls [Internet]. Treasure Island (FL): StatPearls; 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499863/

^[17] Shahrokhi SZ, Ghaffari F, Kazerouni F. Role of vitamin D in female reproduction. Clin Chim Acta. 2016;455:33-38.

^[18] Millward D, Root AD, Dubois J, et al. Association of serum vitamin D levels and stress fractures in collegiate athletes. Orthop J Sports Med. 2020;8(12):2325967120966967.

^[19] Owens DJ, Allison R, Close GL. Vitamin D and the athlete: current perspectives and new challenges. Sports Med. 2018;48(1):3-16.

^[20]Popp KL, Cooke LM, Bouxsein ML, Hughes JM. Impact of low energy availability on skeletal health in physically active adults. Calcif Tissue Int. 2022;110(6):605-614.

^[21] Holtzman B, Popp KL, Tenforde AS, Parziale AL, Taylor K, Ackerman KE. Low energy availability surrogates associated with lower bone mineral density and bone stress injury site. PM R. 2022;14(6):587-596.

^[22] Hosmer WD, Genant HK, Browner WS. Fractures before menopause: A red flag for physicians. Osteoporos Int. 2002;13(4):337-341.

^[23] Sale C, Elliott-Sale KJ. Nutrition and athlete bone health. Sports Med. 2019;49(Suppl 2):139-151.

^[24] Papageorgiou M, Martin D, Colgan H, et al. Bone metabolic responses to low energy availability achieved by diet or exercise in active eumenorrheic women. Bone. 2018;114:181-188.

 

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