intermittent fasting women's cycle

Step-by-Step Protocol to Fasting and Women’s Health

I have talked about fasting and women’s hormones before, but I wanted a more practical post that explained step-by-step what women should do to make sure they fast safely. Before we get started, I do want to emphasize that not all women will need to follow this protocol. I don’t notice much of a difference between how my body reacts to fasting during my cycle. However, some women do. This post will be particularly helpful to women who notice that fasting contributes to hair loss, low sex drive, and interruptions in their cycle.

Intermittent Fasting Benefits for Women’s Health

Although women can experience negative effects from fasting, it is important to realize that the benefits outweigh the risk in most cases. Intermittent fasting will benefit women in the following ways:

  • Increased insulin sensitivity: Insulin sensitivity means your body handles glucose better. Your blood sugar becomes more stable, and that in itself contributes to increased energy, better mood, and improved cognitive function.
  • Ketone production: If you fast long enough and frequently enough, you will start going in and out of ketosis (if you don’t eat keto, if you do eat keto, you will stay in ketosis obviously). When your body runs on ketones instead of glycogen, you notice that your appetite decreases, you feel more energetic and able to focus. Moreover, ketone metabolism decreases inflammation.
  • Metabolic flexibility: Metabolic flexibility means your body is able to use any energy source available (dietary fat, stored fat, glucose (sugar), or glycogen (stored sugar). Being metabolically flexible is good because it will help you experience food freedom. You will notice you will have fewer food cravings and you will be able to go longer between meals.
  • Increased metabolism: Intermittent fasting increases your blood levels of norepinephrine. This increases your metabolism.
  • Weight loss: All the benefits I just mentioned will help you achieve a healthy weight.
  • Increased longevity: Many animal studies demonstrate that fasting and calorie restriction increase lifespan.
  • Improved immune function: Intermittent fasting may induce your body to clean out some old immune cells and replace them with new ones.

Are you convinced yet? Do you see how intermittent fasting can be extremely beneficial to your health and your quality of life? If so, keep reading, we will talk about how you can reap these benefits while avoiding some of the drawbacks to you could experience.

Fasting and Women’s Cycles

The main reason fasting is different for women than men is that women are more sensitive to leptin, which makes them more susceptible to becoming leptin resistant. Leptin resistance may be linked to fertility issues. Fasting increases leptin levels. Moreover, women produce two important hormones that affect their cycles and are affected by fasting. These hormones are estrogen and progesterone.

Fasting Before Menopause

Before menopause, you can pay attention to your cycles to determine if they are being affected by fasting.

Missed Period Due to Fasting

The main thing you need to look for is a missed period due to fasting. Caloric restriction and fasting can stress your body enough to modify the release of estrogen and progesterone through the hypothalamic-pituitary-gonadal (HPG) axis. Excessive exercise can have the same effect. It is important that you make sure you are eating enough calories each day. A reasonable weight loss goal would be 1 pound a week, which amounts to a calorie deficit of around 500 calories a day.

If you thought intermittent fasting eliminated the need for a calorie deficit, read my post Do You Need a Calorie Deficit When Intermittent Fasting or Keto?

Furthermore, ensure that you are focusing on consuming nutrient-dense foods to nourish and support your hormonal function. I enjoy having a raw organic green super shake each day. It provides a generous dose of Vitamin B and iodine, which support my thyroid function. It also is rich in vitamin A, thiamine, iron, niacin, and manganese. Check it out here (this affiliate link will give you a $50 discount).

Intermittent Fasting Post Menopause

After menopause, you won’t be able to see if your fasting is affecting your sex hormones due to a missed period, but you may experience other symptoms, most commonly hair loss and low sex drive. If that’s you, follow the stepd-by-step guide outlined in this post.

Step-by-Step Guide to Fasting and Women’s Health

Premenopausal Women

If you still have your menstrual cycles, it’s a good idea to keep track of them. Use an app on your phone to do so and start understanding your cycles. From the beginning of your cycle to day 12 (if we assume your cycle is 28 days long), you can fast without worrying about negatively affecting your sex hormones like estrogen and progesterone.


From day 12 to day 14, your body needs to produce estrogen, which requires more insulin. You can continue on with intermittent fasting, but no extended water fasts (anything longer than 24 hours). You also need to increase your carb consumption if you are keto or low carb otherwise. A good goal is to bring your carb consumption up to anywhere between 100 and 200 grams. By becoming more metabolically flexible, you will get back into ketosis quicker, so no need to worry about increasing your carb consumption.


Around day 21, your body will produce progesterone. Again, you need to support progesterone production by making sure you are not fasting for more than 24 hours and that you are eating enough carbs. Progesterone helps you feel calm and peaceful. From days 21-28, it is preferable to fast for 18 hours or less. Foods like beans, rice, squash will help support a healthy hormonal function. Women often crave carbs and find they can’t fast during these times.

Perimenopausal Women

If you are perimenopausal and don’t have regular cycles to help you decide when to consume more carbs and fast less, you can start by implementing a 7-day re feeding period. If you have been intermittent fasting and keto, this may be all you need to restart your cycles. Stop fasting for 7 days and build your meals around healthy carbs like fruit, rice, squash, potatoes, and beans.

If your period is not coming back and you don’t like how you were feeling during the re feeding period, you can follow the 28-day protocol for premenopausal women. Cycling through periods of eating more carbs and fasting less is helpful to ensure a healthy hormonal function.

Postmenopausal Women

During perimenopause, your ovaries are shutting down. After menopause, many women still struggle with symptoms they were experiencing during perimenopause like thinning hair, dry skin, insomnia, anxiety, and belly fat. Again, if that’s you , the best course of action is to follow the 28-day protocol for women who are premenopausal.

Women who are postmenopausal still need estrogen and progesterone to function properly. The fact that fasting helps lower your insulin level has many great health benefits, but it can affect your sex hormones negatively. Pay attention to how your body is reacting.

Do Women Need to Fast Differenty Than Men?

In Summary

Yes, intermittent fasting can affect women’s health, particularly if you are eating keto on top of intermittent fasting. Make sure you focus on nutrient-dense foods that nourish your body and support a healthy hormonal function. Carbs have an important role in supporting a woman’s production. If you are a woman, going through cycles of higher carb consumption will help ensure your body is functioning optimally. Fruits, whole grains, beans, potatoes, and squashes are excellent options. Moreover, you don’t need to go keto to benefit from intermittent fasting. If you don’t want to worry about when to eat carbs or not, you can always consume a moderate amount of carbs. That is what I do, and it might be why I haven’t noticed a difference in how I feel at different times during my cycles. For more info read Intermittent Fasting Without Keto: Why It Works.