"My Period Still Hasn't Returned": The Connection Between Estradiol, Amenorrhea, and Eating Disorder Recovery

What Is Amenorrhea?

Amenorrhea refers to the absence of menstrual periods. In eating disorders, the most common type is secondary amenorrhea, which occurs when someone who previously had regular menstrual cycles stops menstruating for three or more consecutive months. While there are many possible causes, one of the most common reasons in individuals with eating disorders is functional hypothalamic amenorrhea (FHA)—a condition in which the brain temporarily suppresses reproductive function due to insufficient energy availability, psychological stress, or significant weight loss (Męczekalski et al., 2023).

For many individuals with eating disorders, losing a menstrual cycle is not simply a reproductive issue. It is often a sign that the body is conserving energy and prioritizing essential functions needed for survival (Męczekalski et al., 2023).

Although amenorrhea was once considered a defining feature of anorexia nervosa, we now know that menstrual disruptions can occur across a wide range of eating disorders, body sizes, and weight histories (Indirli et al., 2022).

The Role of Estradiol

Estradiol is the body's most active form of estrogen during the reproductive years. Produced primarily by the ovaries, it plays a central role in regulating the menstrual cycle while also supporting many other essential functions throughout the body.

Estradiol plays an important role in:

• Regulating the growth and shedding of the uterine lining during the menstrual cycle
• Maintaining bone strength by supporting healthy bone remodeling
• Supporting heart and blood vessel health
• Influencing brain function, mood, and cognitive processes
• Promoting normal ovulation, fertility, and reproductive health

The production of estradiol is controlled by a communication system between the brain and the ovaries. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which signals the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones then stimulate the ovaries to produce estradiol and support ovulation.

When estradiol levels decline, ovulation may not occur regularly, and menstrual cycles can become irregular or stop altogether.

Why Low Estradiol Matters

Many people associate amenorrhea only with the absence of a period. However, low estradiol can have effects throughout the body.

Reduced Bone Density

Estradiol helps maintain bone formation and reduce bone breakdown. Prolonged hypoestrogenism contributes to osteopenia and osteoporosis risk in individuals with FHA and anorexia nervosa (Indirli et al., 2022).

Research suggests that amenorrheic women with anorexia nervosa may experience annual bone mineral density losses of approximately 2–3% at the hip and spine (Indirli et al., 2022).

Cardiovascular Changes

Estrogen supports vascular endothelial function by promoting vasodilation, maintaining vascular integrity, and influencing lipid metabolism. In individuals with anorexia nervosa and functional hypothalamic amenorrhea (FHA), chronic hypoestrogenism may contribute to endothelial dysfunction, adverse lipid profiles, and an increased long-term risk of cardiovascular disease, although these risks are also influenced by chronic energy deficiency and malnutrition (Męczekalski et al., 2023; Friars et al., 2023; Haines, 2023).

Mood and Cognitive Effects

Estrogen interacts with several neurotransmitter systems involved in mood regulation, cognition, and emotional processing (Męczekalski et al., 2023).

In individuals with eating disorders and FHA, chronic hypoestrogenism may contribute to symptoms such as anxiety, depressed mood, impaired concentration, and reduced cognitive flexibility, although these psychological effects are multifactorial and are also influenced by undernutrition and psychosocial stressors (Bonazza et al., 2023; Battipaglia et al., 2023).

Reproductive Health

Low estradiol can impair ovulation and fertility until normal hypothalamic-pituitary-ovarian function resumes (Męczekalski et al., 2023). However, amenorrhea should not be considered as an indicator of infertility. Recovery of ovarian function may precede the first recognized menstrual period, making pregnancy possible even before menstruation resumes (Galusca et al., 2023; Faust et al., 2013). Because this change is often unpredictable, menstrual calendars cannot reliably determine fertility in individuals with amenorrhea. Anyone with questions about fertility, pregnancy, or menstrual recovery should consult their healthcare provider for medical guidance.

What Estradiol Level Is Needed for Periods to Return?

One of the most common questions during eating disorder recovery is whether there is a specific estradiol level needed for periods to return.

Early research suggested that there may be a minimum level. In a landmark study of adolescents with anorexia nervosa, Golden et al. (1997) found that women with a serum estradiol level above 110 pmol/L (approximately 30 pg/mL) were significantly more likely to regain their menstrual cycles. More than 25 years later, this study remains the primary reference cited in research on estradiol and menstrual recovery.

However, despite many studies since then, researchers have not identified a universal estradiol threshold—such as 35 pg/mL or any other specific value—that reliably predicts when periods will return.

Instead, newer research has consistently shown that women who regain their menstrual cycles generally have higher estradiol levels than those who remain amenorrheic. However, estradiol naturally fluctuates during the recovery process, meaning a single blood test cannot accurately predict whether menstruation will return.

Researchers have also found that estradiol is only one part of the picture. Later studies, including Misra et al. (2013), showed that menstrual recovery is more strongly associated with estradiol combined with adequate weight restoration, body fat recovery, and improved overall nutritional status than with estradiol alone.

Building on these findings, more recent reviews emphasize that there is no single estradiol level that guarantees the return of menstruation. Instead, healthcare providers look at several signs of recovery together, including reproductive hormones such as LH and FSH, adequate energy availability, nutritional rehabilitation, weight restoration, the return of ovulation, and spontaneous menstrual cycles (Haines et al., 2023; Męczekalski et al., 2023).

Although estradiol is no longer viewed as the sole predictor of menstrual recovery, it remains an important part of routine clinical care. Current guidelines continue to recommend measuring estradiol alongside LH and FSH because these tests provide valuable information about reproductive hormone function. Estradiol is also one of the most widely available and practical laboratory tests, making it an important tool for monitoring recovery. However, it should always be interpreted together with other hormone levels, clinical findings, and overall progress rather than used as a standalone target.

Can Hormone Replacement Bring Back Periods?

Hormone therapy can increase circulating estrogen levels, but it does not necessarily restore natural ovulation or hypothalamic function.

A withdrawal bleed induced by hormonal medication is not equivalent to spontaneous menstruation resulting from recovered reproductive function (Aalberg et al., 2021).

For individuals with eating disorders, treatment of hypothalamic amenorrhea generally focuses on:

• Restoring adequate nutrition

• Increasing energy availability

• Reducing restrictive eating behaviors

• Addressing psychological stressors

• Medical monitoring

The ultimate goal is recovery of endogenous hormone production rather than increasing estrogen levels pharmacologically alone (Aalberg et al., 2021; Męczekalski et al., 2023).

Menstrual Recovery

Early studies demonstrated that menstrual recovery is associated with:

• Increased caloric intake

• Weight restoration

• Improvements in body fat stores

• Normalization of reproductive hormone function (Golden et al., 1997)

Later, research showed that weight alone does not completely explain menstrual recovery. Some individuals regain periods before reaching a particular weight target, while others remain amenorrheic despite substantial weight restoration (Dalle Grave et al., 2021). In addition, higher body fat percentage was found to significantly predict the return of menses among adolescents recovering from anorexia nervosa (Misra et al., 2013).

Building on these findings, more recent reviews emphasize that menstrual recovery is a multifactorial process also involving:

• Adequate energy availability and nutritional rehabilitation

• Restoration of body composition

• Normalization of reproductive hormone signaling (including estradiol, LH, and FSH)

• Recovery of ovulation

• Reduction of physiological stress (Haines, 2023; Męczekalski et al., 2023; Battipaglia et al., 2023)

Healing Begins When the Body Feels Safe

The body is remarkably adaptive. When energy is scarce, it shifts its priorities to protect vital organs and preserve life—even if that means temporarily putting others on hold. As recovery progresses and the body senses that it is safe again, these systems can gradually begin to recover.

Understanding this process reminds us that healing is rarely about correcting a single hormone or symptom; it is about restoring the conditions that allow the entire body to function as intended. The more we understand how our body's systems work together, the more empowered we become to make informed decisions.

References

Aalberg, K., Stavem, K., Norheim, F., Russell, M. B., & Chaibi, A. (2021). Effect of oral and transdermal oestrogen therapy on bone mineral density in functional hypothalamic amenorrhoea: A systematic review and meta-analysis. BMJ Open Sport & Exercise Medicine, 7(3), e001112. https://doi.org/10.1136/bmjsem-2021-001112

Bonazza, F., Politi, G., Leone, D., Vegni, E., & Borghi, L. (2023). Psychological factors in functional hypothalamic amenorrhea: A systematic review and meta-analysis. Frontiers in Endocrinology, 14, 981491. https://doi.org/10.3389/fendo.2023.981491

Cacciatore, C., Cangiano, B., Carbone, E., et al. (2024). Body weight variation is not an independent factor in the determination of functional hypothalamic amenorrhea in anorexia nervosa. Journal of Endocrinological Investigation, 47(8), 1929–1938. https://doi.org/10.1007/s40618-023-02207-z

Dalle Grave, R., Calugi, S., Marchesini, G., & El Ghoch, M. (2021). Clinical, psychopathological, and biological predictors of resumption of menses in subjects with anorexia nervosa: A 4-year follow-up study. European Psychiatry, 64(S1). https://doi.org/10.1192/j.eurpsy.2021.1340

Faust, J. P., Goldschmidt, A. B., Anderson, K. E., Glunz, C., Brown, M., Loeb, K. L., Katzman, D. K., & Le Grange, D. (2013). Resumption of menses in anorexia nervosa during a course of family-based treatment. Journal of Eating Disorders, 1, 12. https://doi.org/10.1186/2050-2974-1-12

Galusca, B., Gay, A., Belleton, G., Eisinger, M., Massoubre, C., Lang, F., Grouselle, D., Estour, B., & Germain, N. (2023). Mechanisms and predictors of menses resumption once normal weight is reached in anorexia nervosa. Journal of Eating Disorders, 11, 172. https://doi.org/10.1186/s40337-023-00893-x

Golden, N. H., Jacobson, M. S., Sterling, W. M., & Hertz, S. (1997). Resumption of menses in anorexia nervosa. Archives of Pediatrics & Adolescent Medicine, 151(1), 16–21. https://doi.org/10.1001/archpedi.1997.02170380020003

Indirli, R., Lanzi, V., Mantovani, G., Arosio, M., & Ferrante, E. (2022). Bone health in functional hypothalamic amenorrhea: What the endocrinologist needs to know. Frontiers in Endocrinology, 13, 946695. https://doi.org/10.3389/fendo.2022.946695

Męczekalski, B., Niwczyk, O., Battipaglia, C., Troia, L., Kostrzak, A., Bala, G., Maciejewska-Jeske, M., Genazzani, A. D., & Luisi, S. (2024). Neuroendocrine disturbances in women with functional hypothalamic amenorrhea: An update and future directions. Endocrine, 84(3), 769–785. https://doi.org/10.1007/s12020-023-03619-w

Misra, M., Katzman, D., Cord, J., Manning, S. J., Mendes, N., Herzog, D. B., & Miller, K. K. (2013). Percentage body fat by dual-energy X-ray absorptiometry is associated with menstrual recovery in adolescents with anorexia nervosa. Journal of Adolescent Health, 52(5), 592–598. https://doi.org/10.1016/j.jadohealth.2012.10.269

Saadedine, M., & Kapoor, E. (2023). Functional hypothalamic amenorrhea: Recognition and management of a challenging diagnosis. Mayo Clinic Proceedings, 98(9), 1376–1385. https://doi.org/10.1016/j.mayocp.2023.05.027