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Amenorrhoea: The Red Flag

Updated: Jul 23, 2023

As a female athlete, it is not uncommon to miss your period. Here, we discuss why this is a red flag, why it should be taken very seriously, and give strategies to help prevent it.

A loss of menstruation during reproductive years, or amenorrhoea, has traditionally been treated as an acceptable symptom of heavy exercise training—an inevitable consequence that comes with the territory. This is nonsense. Just because something may be common doesn’t mean it's normal. As such, amenorrhoea should be treated as abnormal even in the heaviest of exercisers.


Low Energy Availability

Amenorrhoea forms one part of the Female Athlete Triad (Figure 1), which refers to three interrelated conditions: low bone mineral density, menstrual dysfunction, and low energy availability (LEA) (1). Owing to their interrelated nature, amenorrhoea is oftentimes a symptom of LEA, and thus should be thought of as a red flag, warning of an underlying issue.

Figure 1. Female Athlete Triad (Just Health)

The problem with LEA is that it impairs both health and performance. In a study of menstruating young females eating low-calorie diets while maintaining an exercise routine, a number of negative effects were reported for hormonal markers of bone health, indicating a shift towards lower bone mineral density (2). It’s worth noting that these shifts took place over 5 days, and during normal menstrual function—it’s not a stretch to imagine that these processes are worsened in those without their usual menstrual function, and over a longer time period.

In another study, female adolescent swimmers aged 15–17 who experienced LEA because of a low-calorie intake, and therefore had suppressed ovarian hormones, had significantly worse 400-metre swimming performance compared to those without suppressed ovarian hormones or LEA (3).

Inadequate Carbohydrate Intake

Carbohydrates are particularly important for normal menstrual function because their consumption may keep leptin levels high (4). Leptin is known as a satiety hormone, meaning higher levels help to keep us feeling full. It is also related to menstruation, and evidence suggests that the body needs sufficient leptin levels to maintain normal menstrual function (5). Those eating a low-carbohydrate diet may experience menstrual dysfunction at a higher rate, with 45% of female adolescents in one study reporting menstrual dysfunction on a very-low-carbohydrate, or ketogenic, diet (6).

Healthy sources of carbohydrates: fruits, starchy vegetables, whole grains,

legumes, and potatoes

Within-Day Energy Deficits

Going stretches throughout the day where you’re not eating, or where energy expenditure exceeds energy (kcal) intake, is also a risk factor for amenorrhoea. In a recent study, elite athletes who experienced menstrual dysfunction had more within-day energy deficits, or more time spent in a catabolic state, than those without menstrual dysfunction (7). This was despite the fact that overall energy (kcal) intake and energy balance were quite similar between groups. One caveat is that while overall energy (kcal) intake and energy balance were indeed not statistically different between groups, the menstrual dysfunction group did have objectively lower energy intake and balance, which may have impacted results.


Perhaps unsurprisingly, strategies to alleviate the risk of menstrual dysfunction and amenorrhoea can be largely boiled down to the inverse of the three prior causes, that is:

  • Ensuring you’re eating enough energy (kcal) to fuel your daily activity

  • Ensuring you’re eating an adequate amount of carbohydrates

  • Ensuring you eat regularly throughout the day, which will help you to meet the prior two goals as well as avoiding within-day energy deficits

To calculate how much overall calories you should be eating, check out our previous post on nutrition for the female athlete. To learn more about why carbohydrates are the optimal fuel for performance, and to calculate an evidence-based amount for your activity level, check out our previous posts on the topic.

Finally, if you are experiencing menstrual dysfunction or amenorrhoea, get in touch with a registered health professional to discuss your situation.

While we can't give individualised advice on amenorrhoea, we can for football; reach out to us here: [email protected].

That’s all for this week! I hope you took something valuable from it.

Patrick Elliott, BSc, MPH

Health and Nutrition Science Communication Officer at Training121

Founder of Just Health — IG:

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.


(1) Holtzman B, Ackerman KE. Recommendations and Nutritional Considerations for Female Athletes: Health and Performance. Sports Med. 2021;51(Suppl 1):43-57. Available at:

(2) Ihle R, Loucks AB. Dose-response relationships between energy availability and bone turnover in young exercising women. J Bone Miner Res. 2004;19(8):1231-40. Available at:

(3) 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):156-66. Available at:

(4) Jenkins AB, Markovic TP, Fleury A, Campbell LV. Carbohydrate intake and short-term regulation of leptin in humans. Diabetologia. 1997;40(3):348-51. Available at:

(5) Köpp W, Blum WF, von Prittwitz S, et al. Low leptin levels predict amenorrhea in underweight and eating disordered females. Mol Psychiatry. 1997;2(4):335-40. Available at:

(6) Mady MA, Kossoff EH, McGregor AL, Wheless JW, Pyzik PL, Freeman JM. The ketogenic diet: adolescents can do it, too. Epilepsia. 2003;44(6):847-851. Available at:

(7) Fahrenholtz IL, Sjödin A, Benardot D, et al. Within-day energy deficiency and reproductive function in female endurance athletes. Scand J Med Sci Sports. 2018;28(3):1139-46. Available at:

Technical Terms

Amenorrhoea: The absence of menstruation that can occur during reproductive years.

Female Athlete Triad: A potentially serious condition which is the interplay of LEA, menstrual dysfunction, and low bone mineral density, and negatively impacts both health and performance.

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.

Menstrual dysfunction: Refers to the disruption in the flow or timing of the menstrual cycle, which can include amenorrhoea or irregular periods.

Low energy availability (LEA): A state where an individual does not have enough energy available to sustain all bodily functions, and is associated with a number of health and performance decrements.

Ketogenic diet: A very-low-carbohydrate and high-fat diet that was traditionally used as a treatment for childhood epilepsy, but has gained popularity in recent years as a weight-loss diet. These diets impair exercise performance compared to higher carbohydrate diets, and are not recommended for athletes.

Catabolic: A catabolic state is one where something is broken down. To use muscle as an example, a catabolic activity would be one that leads to the breakdown of muscle, e.g., prolonged sitting.

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