How Does Fasting Affect Reproductive Hormones?

Fasting affects various aspects of your body, including your hormones. For those considering this dietary approach, understanding its effects is crucial. So, we will examine the impact of fasting on reproductive hormones in men and women, based on studies.

So, what effect does fasting have on reproductive hormones?

What are reproductive hormones and their functions?

Reproductive hormones are hormones that are involved in the development and regulation of the reproductive system. They include: 

• Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH): FSH and LH are produced by the pituitary gland. They play a role in the development of the ovaries and testes. 
• Estrogen and Progesterone: They are produced by the ovaries and regulate the menstrual cycle, fertility, and pregnancy.
• Testosterone: It is produced by the testes and is involved in the development of male sexual characteristics. An increase in muscle mass is another important function of testosterone.

The effects of fasting on reproductive hormones

When it comes to reproductive organs, it is necessary to consider the possible effects on men and women separately. In particular, it is important for women to understand what effect fasting can have on their menstrual cycles.

How does the menstrual cycle work and what are its effects on reproductive health?

The menstrual cycle is a process that prepares the uterus for pregnancy. It starts on the first day of menstruation and ends with the first day of the next menstruation. Follicular, ovulatory, and luteal phases make up this cycle. On average, the menstrual cycle of a menstruating woman lasts 28 days.

The menstrual cycle ensures that ovulation occurs and that the endometrial lining stays healthy, which is important for reproductive health. Every month, the lining gets ready to nourish a fetus. Estrogen and progesterone hormones make it thicker.

However, hormone imbalances or irregular periods can cause problems with fertility and reproductive health.

For example, an increase in estrogen in women is linked to adverse health outcomes such as polycystic ovary syndrome (PCOS) and anovulation. One study shows that fasting can lower estrogen levels in women with obesity.

Fasting can be a valuable tool for treating hyperandrogenism in women with PCOS by improving menstruation and fertility.

What are the risks of intermittent fasting during menstruation?

As we said before, the menstrual period is made up of three phases. Each of them causes changes in your body, including changes in:

• Hormones 
• Stress levels 
• Energy needs 
• Appetite

The effects of fasting during the menstrual period are controversial and vary among individuals. According to limited studies, fasting has no effect on reproductive hormones such as estrogen and prolactin. 

However, following a strict diet plan is not recommended, especially during your PMS week and period. Trying to stick to a long-term fasting plan during this time can increase your stress levels. Furthermore, as your energy needs change, you may feel more fatigued.

To avoid these risks, we recommend shortening your fasting windows during your PMS week. You can stop fasting completely, particularly as you approach your period and during the first few days, and then resume with shorter fasting windows (e.g., 14/10 or 16/8).

When you restart fasting, we recommend you get the best fasting app out there, Fasting Kompanion, to track your fasts and get help along your journey in every aspect you can think of.

The key is to listen to your body’s needs and adjust your fasting accordingly, without pushing yourself too hard.

How does intermittent fasting affect sperm quality?

Research finds that intermittent fasting can lower testosterone levels in physically active young men. However, despite the importance of testosterone in muscle mass production, this decrease didn’t have a negative effect on muscle mass or strength. 

There are studies that show that fasting for more than 24 hours reduces sperm count, volume, and motility. Yet, it should be noted that studies and findings in this area are limited.

On the other hand, intermittent fasting has indirect benefits for male fertility. For example, it can improve insulin sensitivity and reduce the risk of diabetes, which are also helpful for male fertility.

Effects of different intermittent fasting plans on reproductive hormones

Intermittent fasting includes many different eating plans, such as 16/8, 5:2, and 12/12. Each plan has its own fasting window, which affects the body in different ways.

In addition to the length of the fasting period, the hours during which you eat also impact your body and hormones.

For example, women with obesity will likely experience a positive effect by reducing their estrogen levels with fasting, and if the eating windows ends at 4 p.m., this effect will increase.

Long-term fasting can negatively affect testosterone levels in men. However, fasting can help decrease androgens, which can in turn have a negative impact on libido. Therefore, when setting a fasting plan, it is important to be careful not to make it too long.

Key takeaways

• Fasting can decrease reproductive hormone levels: Several studies show that fasting may decrease the levels of reproductive hormones such as LH, FSH, and testosterone. This decrease in hormone levels can lead to a disruption in the menstrual cycle, decreased fertility, and a decrease in sperm count.
• The degree of hormone decrease depends on the fasting period: The degree to which fasting affects reproductive hormones varies depending on the fasting plan. For example, short-term fasting may have little effect, while long-term fasting can cause more significant changes.
• Fasting has different effects on males and females: Research suggests that fasting may have a greater impact on male reproductive hormone levels compared to females. This requires further research, however.
• The clinical implications of fasting on reproductive hormones are unclear: Further research is needed to determine if these changes have any long-term effects on reproductive health.

The effects of fasting on reproductive hormones can vary based on the length and intensity of the fast. But still, it is important to consider its potential effects on reproductive hormones, especially for individuals who are trying to conceive.