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Why intermittent Fasting is harming your hormones

Have you heard the news about intermittent fasting?

“Intermittent fasting changed my life!”

“I lost so much weight fasting its incredible!”

“intermittent fasting was the only diet that worked for me!”

You may have heard of intermittent fasting, but, if you haven’t- it is eating within a specific window of the day or alternate day eating. Common ones include:

  • 16/8 where you fast for 16 hours and eat within 8
  • 14/10 fast for 14 hours, eat within 10 hours
  • 20/4 fast for 20 hours, eat within 4 hours
  • alternate day fasting where you eat one day and fast the other, then repeat
  • some may also do 1-2 days a week where they fast

There are many ways to fast. Many benefits have been proven through studies such as increased longevity, improved digestion, improved blood sugar levels, etc. However, almost all of those studies are done on men or postmenoposal women. Why? Because women within their reproductive ages take too long to “study”. We have a 28 day (on average) hormonal cycle that effects different processes in or body including sleep, metabolism, and mood. We would have to be studied for a much longer period of time to determine the long or short term effects of fasting.

unfair? definatly! Though I hope to shed some light on the topic as I have fasted for almost half a year (I do not anymore for reasons I will futher explain). BUT Long story short, I encountered a lot of health problems.

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The menstrual cycle in a nut shell

Reproductive women have 2 distinct phases in their menstrual cycle. The pre ovulation phase (follicular) and the post ovulation phase (luteal). In the follicular phase, estrogen levels rise until the maturing follicle releases an egg. After the egg is release it will either die within 24 hours and your period will come 12-14 days later. OR you are pregnant and the luteal phase will continue as the egg grows. In the luteal phase/after the egg is released, the follicle produces progesterone while estrogen starts to decrease. If your period starts both progesterone and estrogen drop to their lowest levels. If you are pregnant, progesterone will remain elevated.

intermittent fasting and why women should not take part!

Why is this important to know in regards to intermittent fasting?

Fasting can effect the female hormone estrogen, progesterone, and thyroid hormones negativly. Increased cortisol levels (your stress hormone) trigger the hypothalamus (a gland in your brain) it is unsafe to reproduce. In the luteal phase of your cycle, fasting will have a negative effect on progesterone levels leading to a short luteal phase and low progesterone levels. Signs of low progesterone levels include:

  • Anxiety and/or depression
  • Spotting before period
  • Short luteal phase (10 or less days if you track your cycle)
  • Insomnia
  • Irregular cycles

Signs estrogen levels are imbalanced:

  • fatigue
  • weight gain
  • brain fog
  • infertility
  • decreased bone density

signs Thyroid hormone are imblanced:

  • anxiety
  • brain fog
  • dry skin and hair
  • down regulated body temperature

side note: if you track your cycle using the symptom thermal method, your basal body temperature (BBT) will be below 36°C / 97°F. please consult with a doctor to check for hypothyroidism.

Chronically increased cortisol levels may also lead to secondary amenorrhea aka Hypothalamic amenorrhea (HA). Remember HA is when energy balance is out of balance. Therefore, it can stop your period altogether due to stress and low energy availability.

Read: How to get your period back

Fasting can cause weight loss as you are skipping a meal and only able to eat in a specified window of time. Low calorie consumption in regularly exercising women very commonly causes HA. As these studies confirm.

More often than not, a woman will experience hormonal imbalances and/or a loss of period from fasting. However, post menopausal women tend to respond better to fasting as they do not have a high hormones phase (luteal phase). In addition, menopause decreases metabolism and fasting can be a way to control weight in the later stages of life.

Mental effects of fasting

The mental effects of fasting can effect different people in different ways. Biologically, fasting will increase the hormones ghrelin (the hunger hormone) which makes you feel like you need to eat. When one goes long periods without food, ghrelin levels will increase. You may have experienced a time where you did not have access to food for a long period of time (either intentional or unintentional). After you finally had a chance to eat, you ate and you ate a lot.

This is very normal and a means of survival! However, I and many other women who suffered from binge eating and binge eating tendencies find it difficult to control eating when ghrelin levels are high. In addition to the uncomfortable feeling of constant hunger, you may also experience persistent food thoughts. This is also a way to get you to feed your body as it feels like it is in a famine. Which, fasting is considered a controlled period of not eating so I can understand how your body may have missed the memo.

If you have a history with disordered eating, binge eating, or chronic dieting, I highly suggest against trying to fast regularly. I understand some religions do annual fasts which defiantly take part in if that’s what you want! Just be carful<3

Effects I personally experienced while intermittent fasting

While I was intermittent fasting I followed the 16/8 approach. I would skip breakfast in the morning and eat from noon to 7pm. It was absolutely horrible now that Im reliving it writing this article. My mornings were filled with food thoughts and looking at the clock waiting until 12pm to strike. 16 long hours spent thinking about my meal was the biggest waste of time.

I experienced brain fog and low concentration at work, My workouts were horrible as I was so tired all the time. Plus, my period went MIA despite me making sure I was eating enough within the 8 hour window. The physiological stress got the best of me for sure.

Running on coffee and tea in the morning was absolutely horrible for my hormones as well. We naturally have a spike in cortisol levels in the morning to wake us up. Coffee also increases cortisol levels so I was drinking about 2 cups of coffee before I ate anything. Talk about blood sugar imbalance.

Needless to say, fasting is not for me BUT that doesn’t mean its terrible and won’t work for anyone else! here is how women can safely implement fasting into their lives.

Intermittent fasting is like watching the clock tick away. when can i eat again?!

How reproductive women can implement fasting

If you are interested in reaping the benefits of fasting, you do not need to go far! A 12-hour fast is plenty and safer for us women to implement. Fasting is just a time restricted eating window not a FOOD restricted eating window. Please be sure to eat enough calories for your body to function and monitor your hormones as they will tell you if it works for you or not;)

I recommend women do not fast more that 12 hours, if you choose to go more than that do not do strenuous exercise the same day. Remember: we are limiting stress so calorie restriction, long bouts without food, and intense exercise is a recipe for hormonal disaster.

Additionally, if you are pregnant, it is not a good idea too fast!

Concluding thoughts on fasting for reproductive women

In conclusion, fasting is not for me. It may be for you but be sure to do your research on the topic before you dive into it. Fasting can negatively effect your reproductive hormones and hunger hormones to work against you. It can cause infertility and constant food thoughts. That does not sound like a very healthy place to be if you are going to fast for you “health” benefits. Let me know what you think in the comment section. Have you fasted before? What was your experience?

Until next time
-Hailee xx


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