Recognising that nutritional needs can differ by sex, in this article, we shed light on some important nutritional factors that all female athletes should be aware of.
Introduction
Unfortunately, much of the research into nutrition and athletic performance has focused on male participants, meaning that general sports nutrition recommendations may not be as applicable to women, as they are to men. From 2011–2013, only 39% of research participants in three of the top sports medicine journals were women (1), and only 4% of studies were female-only (2). In this article, we will address some of the nutritional considerations that are especially important for the female athlete.
Nutritional Needs for Females vs. Males
When it comes to nutritional requirements, there are some differences to consider between females and males. For example, females require approximately double the recommended daily allowance (RDA) of iron than males, largely due to the iron losses from menstruation. The following paragraphs lay out some of the most important nutritional considerations for female athletes to bear in mind.
Daily energy needs
Despite the fact that energy, or calorie (kcal), needs are generally lower for females compared to males, females are at particular risk for experiencing low energy availability (LEA)—a recent survey estimated prevalence in young female athletes of up to 47% (3). Energy availability (EA) represents the daily amount of energy available to sustain all bodily functions outside of exercise, e.g., digestion, thinking, etc. (4), and naturally, LEA is a low amount, or low availability, of this energy.
LEA is linked to a host of health issues. Specifically, LEA has been associated with low bone mineral density, dysregulated hormones, and amenorrhoea (the absence of menstruation) (4,5). LEA is suspected to be the underlying cause of the Female Athlete Triad (Figure 1) and Relative Energy Deficiency in Sport (RED-S; Figure 2), two conditions associated with poor health and performance (5). It is no surprise that there are data to suggest that female athletes with LEA suffer poor performance (6).
Figure 1. The Female Athlete Triad (Just Health).
Figure 2. Health and Performance effects of RED-S (5).
As a female athlete, eating enough should be your first priority when it comes to staying healthy and performing well. This means fuelling properly before and after training, as well as throughout the day. An optimal EA of about 45 kcal per kilogram of fat-free (lean) mass per day (kcal/kg/FFM/d) is suggested as ideal for the maintenance of body mass (5). If you are a fit and active 60 kg woman, this means a daily kcal intake of approximately *2,150–2,750 kcal per day depending on whether you’re exercising lightly or vigorously on a given day. As is always the case with calculations like this, they may not exactly reflect your individual energy needs, so bear in mind that if you’re a fit and active 60 kg woman, you may need a higher or lower daily kcal intake than this general recommendation.
*EA: (energy intake [EI] - exercise energy expenditure [EEE]) divided by fat-free (lean) mass (FFM). To calculate energy intake for a fit and active 60 kg woman, we assume an approximate body fat percentage of 20%. This makes her FFM at 48 kg (20% of 60 = 12; 60 - 12 = 48). If we assume that no exercise has taken place for the day, we get 2,150 kcal as the amount that gives us an EA figure of ~45 kcal/kg/FFM/d (2,150 - 0 / 48 = ~45); If we assume moderate exercise has occurred (EEE: 300 kcal), then we get a figure of 2,450 kcal (2,450 - 300 / 48 = ~45); if we assume a heavy day of training has occurred (EEE: 600 kcal), then we get a figure of 2,750 kcal (2,750 - 600 / 48 = ~45).
Daily Carbohydrate Needs
In the follicular (pre-ovulation) phase of menstruation, the body can make glucose at a faster rate than when in the luteal (post-ovulation) phase of ovulation (5). In addition, the body’s ability to use glucose as a fuel for exercise is slightly worse in the luteal phase. This can potentially be corrected by ensuring you eat a high-carbohydrate meal about 3–4 hours before exercise (5), and by eating some carbohydrates during exercise (7). For a more detailed discussion of pre-, intra-, and post-exercise fuelling recommendations, check out last week’s post.
Daily Micronutrient Needs
Iron
As mentioned earlier, the RDA for iron is approximately double for adult menstruating females compared to males. Menstruating females are more likely to fall short of daily iron needs because they eat less food than males—and therefore less iron—and are more likely to have LEA (5). Recommended intakes for females:
Aged 14–18: 15 milligrams per day (mg/d)
Aged 19–50: 18 mg/d
Menstruating athletes: ~22 mg/d
Tips to improve iron status: don’t eat tea/coffee around meals (~1 hour before/after as tannins in tea/coffee decreases iron absorption); eat vitamin C with iron-rich foods (as vitamin C increases iron absorption), e.g., red bell pepper with lentils; take an iron supplement.
Calcium
Again, because female athletes are at higher risk for LEA, and therefore low food (and calcium) intake, ensuring proper calcium intake is important. Calcium is particularly important for bone health, and females should shoot for 1,000 mg/d or more. Good sources of calcium include milk/yoghurt or fortified plant-based milks/yoghurts (e.g., soy), white beans, and leafy greens like kale. If you are struggling to meet recommendations, consider taking a calcium supplement.
Vitamin D
Most people don’t get enough vitamin D through their diet, so a supplement of ~25–50 micrograms per day (mcg/d) (1,000–2,000 International Units [IUs]) is a good way to ensure sufficient intake and status (5). This is particularly important during the darker months of the year (October–March in the Northern Hemisphere). Ensure your supplement is vitamin D3 (not D2), as it is the more bioavailable form.
Summary
If you’re a female athlete looking to improve your health and performance, you need to take on board the recommendations here. I can’t emphasise this enough: fuelling incorrectly can have lifelong negative health consequences, so ensuring you’re fuelling well and getting a source of these key nutrients is vital. What’s more, you’ll likely feel and perform better, too.
With this nutrition knowledge under your belt, why not improve your football knowledge, too, and book in for a session by contacting us here: [email protected].
Have a lovely weekend!
Patrick Elliott, BSc, MPH
Health and Nutrition Science Communication Officer at Training121
Instagram: @just.health.info
Twitter: @PatrickElliott0
Health Disclaimer: this article is for informational and educational purposes only, and is not a substitute for professional advice. For health advice, speak to a physician or other qualified health-care professional, and for nutrition advice, speak to a qualified nutrition professional (e.g., registered dietitian). The use of information on this site is solely at your own risk.
References
(1) Costello JT, Bieuzen F, Bleakley CM. Where are all the female participants in Sports and Exercise Medicine research?. Eur J Sport Sci. 2014;14(8):847-51. Available at: https://pubmed.ncbi.nlm.nih.gov/24766579/
(2) Brookshire B. Women in sports are often underrepresented in science. 2016. Science News. Available at: https://www.sciencenews.org/blog/scicurious/women-sports-are-often-underrepresented-science
(3) Ackerman KE, Holtzman B, Cooper KM, et al. Low energy availability surrogates correlate with health and performance consequences of Relative Energy Deficiency in Sport. Br J Sports Med. 2019;53(10):628-33. Available at: https://pubmed.ncbi.nlm.nih.gov/29860237/
(4) Areta JL, Taylor HL, Koehler K. Low energy availability: history, definition and evidence of its endocrine, metabolic and physiological effects in prospective studies in females and males. Eur J Appl Physiol. 2021;121(1):1-21. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815551/
(5) Holtzman B, Ackerman KE. Recommendations and Nutritional Considerations for Female Athletes: Health and Performance. Sports Med. 2021;51(Suppl 1):43-57. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8566643/
(6) Vanheest JL, Rodgers CD, Mahoney CE, De Souza MJ. Ovarian suppression impairs sport performance in junior elite female swimmers. Med Sci Sports Exerc. 2014;46(1):156-166. Available at: https://pubmed.ncbi.nlm.nih.gov/23846160/
(7) Campbell SE, Angus DJ, Febbraio MA. Glucose kinetics and exercise performance during phases of the menstrual cycle: effect of glucose ingestion. Am J Physiol Endocrinol Metab. 2001;281(4):E817-25. Available at: https://pubmed.ncbi.nlm.nih.gov/11551860/
Technical Terms
Recommended Daily Allowance (RDA): The levels of intake of essential nutrients that, on the basis of scientific knowledge, are judged to be adequate to meet the known nutrient needs of practically all healthy people (approximately 97.5% of the needs of the population).
Energy availability (EA): The daily amount of energy available to sustain all bodily functions outside of exercise, e.g., digestion, thinking, etc.
Low energy availability (LEA): A state where an individual does not have enough energy available to sustain all bodily functions. LEA is associated with a number of health and performance decrements.
Bone mineral density: A measurement of the amount of bone mineral in bone tissue; the higher the measurement, the stronger, or 'denser', the bone. Low bone mineral density is a risk factor for osteoporosis.
Amenorrhoea: The absence of menstruation that can occur during reproductive years. LEA is a risk factor for amenorrhoea.
Female Athlete Triad: A potentially serious condition which is the interplay of LEA, menstrual disturbance, and low bone mineral density.
Relative Energy Deficiency in Sport (RED-S): A condition of LEA that can affect females and males. It is associated with a host of health and performance decrements.
Follicular phase: The first phase of the menstrual cycle that occurs before ovulation.
Luteal phase: The last phase of the menstrual cycle that occurs after ovulation.
Glucose: All carbohydrates are broken down into this simple sugar molecule. It is the only sugar molecule that can be used to create energy (ATP) in the human body.