Keto and Menstruation: Can Keto Affect a Woman’s Period?

Some women have heard that a ketogenic diet could affect their menstrual cycle, so they feel it’s worth exploring. The truth is that there is very little research on the effects of a keto diet and menstruation, but there is a lot of speculation. Some women believe that there is evidence to support the possibility that a keto diet could cause menstrual abnormalities, such as a shortened cycle, abnormal bleeding, or an absence of periods.

Keto is a popular diet that promises to help you lose weight rapidly, as well as the associated benefits of improved energy, reduced hunger and cravings, and even better sex. It is also becoming popular among women, but is there any truth to the claim that a ketogenic diet can affect a woman’s period?

The short answer is : Yes!

Diet, weight and stress contribute to changes in hormones in both women and men. However, because of the female reproductive system, they tend to have more hormonal side effects when it comes to diet and weight loss. That’s why you’ll find several forums, websites and books that deal specifically with women and the keto diet.

Nutrition has a huge impact on the way our bodies function. So changes in menstruation are not surprising when switching to the keto diet. However, some women experience more frequent menstrual changes than others.

Is there any cause for concern? It can really depend on a number of factors, but in general, a healthy and well-constructed keto diet helps rather than hinders a woman’s reproductive health (i.e. menstruation and hormones).

Let’s start with period 101:


A woman’s menstrual cycle consists of 4 distinct phases with significant hormonal changes in each phase. The normal menstrual cycle lasts an average of 28 days, plus or minus one week.

  1. Menstrual phase : The first day is the first day of your period and lasts from 3 to 7 days.
  2. Follicular phase: overlaps with the menstrual phase from day one and lasts ~16 days on average.
  3. Ovulation phase (also called birth phase): it begins on day 14, in the middle of the menstrual cycle, and lasts about 24 hours.
  4. Luteal phase (also called premenstrual syndrome phase): lasts about 14 days after the ovulation phase.

Hormones that are affected by menstruation, diet and stress are luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol, progesterone, insulin, cortisol, leptin and ghrelin.

At each stage, different hormones are affected, leading to physical and emotional changes. It is also important to note that some phases (PMS phase) also affect other hormones (such as insulin and cortisol) and cause fluctuations in both insulin sensitivity and blood sugar levels.

What does this mean? Lower ketone levels, weight changes and more cravings for food/carbs are absolutely NORMAL and a good sign of a healthy reproductive cycle.

Can the keto diet affect my period?

Unfortunately, there is not enough research in this area, but many women anecdotally report positive and negative changes in their menstrual cycle when they begin the keto diet.

In my experience, people who report negative changes usually find that things normalize (and often improve) after a few months of a healthy keto lifestyle. Low-carb diets like the keto diet have helped many women with PCOS (polycystic ovarian syndrome), one of the leading causes of female infertility and irregular menstrual cycles. However, to date, only one small study has tested the effects of the keto diet on PCOS, with positive results.

But my period is getting smarter!

Here are some reasons why:

  • Fast weight loss
  • Stress (physical and emotional)
  • Excessive calorie restriction

Ketonic or not, the above causes can (and will) lead to changes in the hormones that affect a woman’s menstrual cycle. Try to take a step back and see if you are limiting carbs, protein, fat and calories in general. Then find out if increasing some of these substances can restore the balance of hormones and physical stress.

However, if you are following a well thought out keto diet, you need to give your body time to adjust to this new lifestyle.

Remember, a change in your period doesn’t mean everything is okay. Unwanted and unpleasant side effects – such as For example, periods lasting longer than usual, spotting or irregular periods – do not necessarily mean that everything is bad or unhealthy. If your period is irregular but you feel generally well, give your body a few months to adjust or see your doctor.

In the meantime, make sure you have an optimal diet, consume calories and adopt good habits to reduce stress (sleep, meditation, walks, sun exposure, yoga, etc.).

Frequently Asked Questions

Can Keto affect menstrual cycle?

The ketogenic diet can affect the menstrual cycle. It is not recommended to follow a ketogenic diet during pregnancy or while breastfeeding.

Can change in diet affect period?

Yes, a change in diet can affect the length of your period.

What does Keto do to female hormones?

Keto can have a negative impact on female hormones. This is because the body uses ketones as fuel, and when you are in ketosis, your body will use fat for energy instead of glucose. When this happens, the body will produce less estrogen and progesterone. What does Keto do to male hormones? Keto can have a negative impact on male hormones. This is because the body uses ketones as fuel, and when you are in ketosis, your body will use fat for energy instead of glucose. When this happens, the body will produce less testosterone.

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