The Blood Sugar and Cortisol Connection in FHA: What the Research Says
You lost your period, and somewhere along the way you wondered whether balancing your blood sugar might be relevant to you. It is a reasonable thing to wonder, since the advice is everywhere, and the research gives a more specific answer than most of what you will have read.
Where the blood sugar advice comes from
“Balance your blood sugar” grew up in the world of type 2 diabetes, insulin resistance and polyendocrine metabolic ovarian syndrome (PMOS), the new name for polycystic ovary syndrome (PCOS) agreed through a global consensus in 2026 [1]. In PMOS, a meta-analysis of gold-standard clamp studies found insulin sensitivity was on average 27% lower than in women without it, independent of BMI [2]. When the challenge is high insulin and cells that respond less effectively to it, softening glucose spikes makes sense.
FHA accounts for 20 to 35% of secondary amenorrhoea, making it the second most common cause after PMOS, and polycystic-looking ovaries on ultrasound appear in 41.9% to 46.7% of women with FHA [3]. These two hormonal conditions can look alike on paper. Working out which picture fits matters, because the physiology (and recovery) point in very different directions.
What blood sugar looks like in FHA
In FHA, the hypothalamus slows the pulses of GnRH, the signal that sets each cycle in motion. Alongside this, we often see an energy deficit that can happen at any body weight, raised cortisol, a thyroid that quietens down to conserve energy and, especially in active women, higher ghrelin and lower leptin [4].
In the small studies that measured it, glucose and insulin run low, not high. Eight non-athletic women with FHA had lower glucose and insulin during the eating part of the day than eight matched women with regular cycles, even though daily calorie intake was similar [5]. In athletes, insulin sensitivity was higher and insulin lower whether or not they had periods, and those without periods also had lower glucose [6].
So, according to the evidence, your body is not struggling to clear sugar. It is handling glucose with great economy, which is what a body does when it senses fuel is scarce.
In my clinic, we include a simple blood test that shows your average blood glucose levels over the past 2-3 months. This ‘long term report card’ for your blood sugar helps us evaluable whether the evidence is true for you, and how we can best support you.
Where cortisol fits
Part of cortisol’s job is keeping blood sugar steady when supply feels uncertain. Stress-axis activation and reduced GnRH drive are tightly linked [4], and in the non-athletic FHA study, the more cortisol rose and insulin action fell, the more GnRH pulses slowed [5]. In women with regular cycles, LH pulses were disrupted once energy availability dropped low enough, tracking most closely with blood glucose and cortisol among other markers [7].
In FHA, raised cortisol looks less like a blood sugar problem and more like your body’s response to the whole picture: not enough fuel for everything being asked of it, layered with stress. A mismatch your body noticed before you did.
What the research supports, and where it stops
What is well established is that low energy availability underlies menstrual disruption in active women, and that correcting the energy imbalance is often the first foundation of recovery [8].
Energy balance is the core principle, but FHA usually involves several factors at once [4], including other nutritional imbalances that may sit alongside low energy availability. These may relate to energy distribution, dietary composition and even micronutrient status. Research on these in FHA is still limited, and each woman is unique, which is where working with a specialist registered nutritionist or dietitian can make a real difference. In clinic, I work through each woman’s history, symptoms and, where appropriate, test results, so that what we change fits her body and her life.
What is plausible but less certain is how much each factor matters for any one woman. A 2025 systematic review of dietary support in FHA without an eating disorder found only 11 studies, with the non-randomised ones at moderate-to-high risk of bias, and the publisher’s summary describes intake rising by around 350 kcal a day and periods returning anywhere from 1 to 12 months [9], which is an average across small studies, not a target or a timeline for you.
What is clear from the evidence is that your blood sugar is unlikely to need taming. Because recovery often rests on restoring adequate energy availability [8], approaches built around fasting windows or close glucose tracking are generally discouraged.
The limits of this research
The direct data on glucose and insulin in FHA come from two small studies in the 1990s [5, 6], and no systematic review covers them. The cortisol findings show association, not cause, and the key experiment ran for five days in women with regular cycles [7]. Recovery data come from a handful of small studies [9], and much of the research is in athletes.
What this means for you
If you have been policing your blood sugar, you are allowed to loosen your grip on it. Your body is not misfiring, it is protecting you, and the signal it is waiting for is safety, which often includes enough fuel and a variety of different types of carbohydrates. Whatever changes recovery ends up asking of your food and lifestyle, it should never ask you to become someone else, and the foods you love should always stay.
REFERENCES
Teede HJ, Bahri Khomami M, Morman R, Laven JS, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. The Lancet. 2026, 407(10545): 2329-2339. https://pubmed.ncbi.nlm.nih.gov/42119588/ [Global consensus statement]
Cassar S, Misso ML, Hopkins WG, Shaw CS, Teede HJ, Stepto NK. Insulin resistance in polycystic ovary syndrome: a systematic review and meta-analysis of euglycaemic-hyperinsulinaemic clamp studies. Human Reproduction. 2016, 31(11): 2619-2631. https://doi.org/10.1093/humrep/dew243
Ott J, Robin G, Hager M, Dewailly D. Functional hypothalamic amenorrhoea and polycystic ovarian morphology: a narrative review about an intriguing association. Human Reproduction Update. 2025, 31(1): 64-79. https://doi.org/10.1093/humupd/dmae030 [Narrative review]
Gordon CM, Ackerman KE, Berga SL, Kaplan JR, Mastorakos G, Misra M, Murad MH, Santoro NF, Warren MP. Functional hypothalamic amenorrhea: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism. 2017, 102(5): 1413-1439. https://doi.org/10.1210/jc.2017-00131
Laughlin GA, Dominguez CE, Yen SSC. Nutritional and endocrine-metabolic aberrations in women with functional hypothalamic amenorrhea. Journal of Clinical Endocrinology and Metabolism. 1998, 83(1): 25-32. https://doi.org/10.1210/jcem.83.1.4502 [Small original study]
Laughlin GA, Yen SSC. Nutritional and endocrine-metabolic aberrations in amenorrheic athletes. Journal of Clinical Endocrinology and Metabolism. 1996, 81(12): 4301-4309. https://doi.org/10.1210/jcem.81.12.8954031 [Small original study]
Loucks AB, Thuma JR. Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women. Journal of Clinical Endocrinology and Metabolism. 2003, 88(1): 297-311. https://doi.org/10.1210/jc.2002-020369 [Original controlled experiment]
Mountjoy M, Ackerman KE, Bailey DM, Burke LM, Constantini N, Hackney AC, et al. 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine. 2023, 57(17): 1073-1097. https://doi.org/10.1136/bjsports-2023-106994
Amoroso AP, Fiorini S, Lopes Neri LC, Guglielmetti M, Tagliabue A, Nappi RE, Ferraris C. Functional hypothalamic amenorrhea and dietary intervention: a systematic review to guide further research in amenorrheic women without overt eating disorder. Nutrition Research. 2025, 140: 102-115. https://doi.org/10.1016/j.nutres.2025.06.008
Updated: 12th October 2026
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