The ketogenic diet (KD), characterized by low carbohydrate and high fat intake, has gained popularity for its potential benefits, including weight loss and improved metabolic health. While research has focused on its effects on weight management and metabolic parameters, emerging evidence suggests that KD can also influence women's menstrual health. This article explores the intricate relationship between the ketogenic diet and menstruation, examining its potential benefits and drawbacks, and providing insights into how it impacts hormonal balance and reproductive health.
Understanding the Ketogenic Diet
A well-formulated ketogenic diet (KD) is a nutrient-dense, whole-food lifestyle approach primarily characterized by its unique ability to increase blood ketones into a safe, and potentially therapeutic, range of nutritional ketosis (0.5-4.0 mM beta-hydroxybutyrate; R-βHB). Ketosis is rapidly inducible (~3-5 days) when carbohydrates are limited and primarily derived from non-starchy vegetables (20-50 g/day), protein is consumed in moderation (1.2-1.6 g/kg BW/day), and lipids fulfill the daily energy requirements and satiety. If sustained over time, ketosis can modulate blood parameters positively, both during weight-loss and weight-maintenance.
The Interplay Between Hormones and Menstruation
To understand how the ketogenic diet impacts menstruation, it's crucial to grasp the complex interplay of hormones that govern the menstrual cycle. The hormones are regulated by three major glands: Hypothalamus, Pituitary, and Adrenals. All three glands interact in complex ways to keep your hormones in balance. This is known as the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is responsible for regulating your stress levels, mood, emotions, digestion, immune system, sex drive, metabolism, energy levels, and more. The glands are sensitive to things like calorie intake, stress, and exercise levels.
Any diet that severely restricts calories, including some low carb diets, may disrupt certain hormones in some women. If your diet is very restrictive, you may experience irregular menstrual cycles or amenorrhea. Amenorrhea is defined as the absence of a menstrual cycle for 3 months or more. The most common cause of amenorrhea is functional hypothalamic amenorrhea, which can result from a very low calorie diet, disordered eating, losing weight, experiencing stress, or getting too much exercise. Restricting carbs could contribute to some of these causes. Amenorrhea occurs as a result of the drop in levels of many hormones, such as gonadotropin-releasing hormone, which starts the menstrual cycle. This results in a domino effect, causing a drop in the levels of other hormones such as luteinizing hormone, follicle-stimulating hormone, estrogen, progesterone, and testosterone. These changes can slow some functions in the hypothalamus, the region of the brain responsible for hormone release. A low level of leptin, a hormone produced by fat cells, is another potential cause of amenorrhea and irregular menstruation. Research suggests that women need a certain level of leptin to maintain normal menstrual function. If your carb or calorie consumption is too low, it may suppress your leptin levels and interfere with leptin’s ability to regulate your reproductive hormones. This is particularly true for underweight or lean women on a low carb diet.
Ketogenic Diet and Menstrual Cycle Changes: Research Findings
Recent studies have shed light on the effects of KD on menstrual physiology. A study published in PLOS ONE compared the impact of a hypocaloric ketogenic diet (75% of energy to maintain weight), supplemented with and without daily exogenous ketones, to a low-fat diet in pre-menopausal women with overweight and obesity. The women received a precisely weighed and formulated KD with either twice-daily ketone salts or a flavor-matched placebo daily for 6 weeks. Researchers compared results with an age and BMI-matched cohort of women who received a low-fat diet with a flavor-matched placebo. Both ketogenic diets provided approximately 40 g per day of carbohydrates, with remaining non-protein calories coming from fats, with an emphasis on monounsaturated and saturated fat sources. The low-fat diet contained 25% of energy from lipids, with less than 10% being saturated fat and less than 30 g of added oils. All participants self-reported menses fluctuations. Researchers also assessed body weight, body composition via dual-energy X-ray absorptiometry and fasting blood samples biweekly.
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The study revealed that women on the KD reported menstrual changes, while those on the LFD did not, suggesting a unique effect of the KD on menstrual physiology, possibly due to a ketone body. Specifically, 30% of women in the ketogenic diet plus exogenous ketones group and 43% of women in the ketogenic diet alone group self-reported increased menses frequency and intensity after 14 days. After 28 days, another 30% and 33% of women in the ketosis with and without supplementation groups, respectively, reported menses restarted after a stall of more than 1 year.
These findings indicate that nutritional ketosis with or without exogenous ketone supplementation may positively impact self-reported menses for women, restarting or realigning menstrual cycles.
Potential Mechanisms Behind the Effects
The precise mechanisms through which KD influences menstruation are still under investigation. However, several factors may contribute to the observed changes:
Weight Loss and Insulin Sensitivity
Weight loss can positively alter female physiology; however, whether dietary carbohydrate- or fat- restriction confer unique effects is less studied. Both KD and LFD achieved significant reductions in weight, BMI, body fat, insulin levels, and cardiovascular risk factors. Significant weight loss (7.1 kg on average) and BMI reductions (2.6 kg/m2 on average) were seen during the study period. Insulin sensitivity improved with weight loss.
Excess adiposity, primarily stored as visceral adipose tissue, can alter healthy physiology, specifically glucose metabolism. The arising metabolic sequelae manifest as fasting hyperglycemia (> 100 mg/dL), hypertriglyceridemia (> 150 mg/dL), and impaired insulin signaling-features that describe the early onset of insulin-resistance. Approximately 4-in-10 adult women in the US have been diagnosed with pre-diabetes or diabetes , an insulin-resistant condition that increases their propensity for developing sex-specific endocrinopathies (i.e., polycystic ovary syndrome), irregular menses, amenorrhea, and infertility.
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Ketone Bodies and Hormonal Regulation
The ketogenic diet converts fat into ketones used by cells in the body and brain as an alternative to glucose. Supplements also elevate blood ketones without a change in eating habits. It was just the presence of ketones that essentially changed the menstrual cycle.
Impact on Gonadotropin-Releasing Hormone (GnRH)
Another hormone that seems to mess with period regularity is the gonadotropin-releasing hormone (GnRH). GnRH is the signal for pituitary production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are responsible for stimulating ovarian production of estrogen and progesterone, and therefore ovulation). A small study published in the Journal of Translational Medicine in February 2020 found overweight women with PCOS who followed the keto diet for 12 weeks lost a significant amount of weight and also saw a decrease in the ratio between LH and FSH, which is a healthier balance between the two.
Ketogenic Diet and Polycystic Ovary Syndrome (PCOS)
PCOS is a common endocrine disorder that affects 6-12% of women of reproductive age. Characterized by irregular menstrual cycles, insulin resistance, and elevated androgen levels, PCOS can lead to infertility and other long-term health complications. The ketogenic diet may be an effective intervention for managing PCOS due to its impact on insulin sensitivity and weight management.
Improved Insulin Sensitivity
Insulin resistance is a hallmark of PCOS, contributing to hormonal imbalances and metabolic dysfunction. By significantly reducing carbohydrate intake, the ketogenic diet lowers insulin levels, thereby improving insulin sensitivity. This can help regulate ovulation and reduce symptoms of PCOS.
Weight Management
Many women with PCOS struggle with weight gain or difficulty losing weight due to metabolic dysfunction. The ketogenic diet promotes fat loss by encouraging the body to use stored fat as its primary energy source. Studies have shown that weight loss achieved through keto can improve menstrual regularity, reduce androgen levels, and enhance fertility in women with PCOS.
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A meta-analysis of clinical trials evaluating the effects of ketogenic diet in established PCOS women consistent with the Rotterdam classification showed that following ≥45 days of intervention with ketogenic diet among women with PCOS, significant improvement was observed in reproductive hormone levels, with reduced LH/FSH ratio, reduced serum free testosterone, and an increased in serum sex hormone binding globulin (SHBG).
Potential Drawbacks and Considerations
While the ketogenic diet may offer potential benefits for menstrual health, it's essential to be aware of potential drawbacks and considerations:
Irregular Menstrual Cycles or Amenorrhea
If your diet is very restrictive, you may experience irregular menstrual cycles or amenorrhea. Following a very low carb (ketogenic) diet over a long period of time may cause irregular menstrual cycles or amenorrhea.
Thyroid Function
Very low carb diets may cause a drop in thyroid function in some people. This may result in fatigue, weight gain, and low mood.
Nutritional Adequacy
Ensure adequate intake of essential nutrients, particularly fiber, vitamins, and minerals, by incorporating non-starchy vegetables, nuts, seeds, and healthy fats.
Transition Period
The initial phase of ketosis, often referred to as the “keto flu,” can cause temporary fatigue, headaches, and irritability as the body adapts to using fat for energy.
Individual Needs
Women with certain medical conditions, such as thyroid disorders or eating disorders, should consult a healthcare provider before starting the ketogenic diet.
Dietary Recommendations and Carb Intake
The optimal amount of dietary carbs varies for each individual. However, the Dietary Guidelines for Americans recommend that carbs make up 45-65% of your daily calorie intake. Furthermore, the Food and Drug Administration states that for a 2,000-calorie diet, the Daily Value for carbs is 275 grams per day.
A large 2018 study looked at carb intake in middle-aged adults. In this group, eating a moderate amount of carbs - that is, 50% to 55% of your total calories - was associated with the lowest risk of dying. This means that people with a moderate carb intake were likely to live longer than people with low or high carb diets.
Who Might Benefit from a Moderate Carb Intake?
Given the potential side effects of restrictive diets, certain women may do better consuming a moderate amount of carbs. This may include women who:
- are very active and struggle to recover after training
- have an underactive thyroid, despite taking medication
- struggle to lose weight or start gaining weight, even on a low carb diet
- have stopped menstruating or are having an irregular cycle
- have been on a very low carb diet for an extended period of time
- are pregnant or breastfeeding
For these women, benefits of a moderate-carb diet may include weight loss, improved mood and energy levels, normal menstrual function, and better sleep. Other women, such as athletes or those trying to gain weight, may find a higher daily carb intake appropriate. Your doctor or a registered dietician can help you create a healthy eating plan.
Who Might Benefit from a Low Carb Intake?
Certain women may do better sticking to a low carb diet. This includes women who have:
- overweight or obesity
- a very sedentary lifestyle
- epilepsy
- polycystic ovary syndrome, fibroids, or endometriosis
- yeast overgrowth
- insulin resistance
- type 1 or type 2 diabetes
- a neurodegenerative condition such as Alzheimer’s disease or Parkinson’s disease
- certain forms of cancer
Catamenial Epilepsy and Ketogenic Diet
Interactions between seizures and menstrual cycle are possible, as suggested by variations in seizure frequency according to the day, phase and ovulatory status of the menstrual cycle, configuring “catamenial epilepsy”. Whether patients with DRE undergoing KDT and likely to have catamenial exacerbations might benefit from an individualized treatment approach aimed at increasing ketogenic ratio in the time window of menstruation period remains to be investigated.
Preliminary Results on Glucose and Ketone Levels During Menstruation
A longitudinal multicenter study aimed at investigating the ketone bodies and glucose blood levels during menstrual cycle in female patients with a diagnosis of GLUT1-DS or drug resistant epilepsy undergoing CKD, found a significant increase in glucose blood levels during menstruation was found in the entire cohort. Ketone bodies blood levels were found to be lower during menstruations in 4/6 patients, even if not statistically significant.
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