Read This Before Intermittent Fasting Another Day

Fasting is a powerful tool for improving health and longevity. It helps with mental clarity and energy levels. It promotes metabolic flexibility (our ability to switch between using glucose and fatty acids for energy) which is important for stable blood sugar. It’s a way to restrict calories for weight loss. It activates the immune system. It promotes cell repair, and more!

And because of these benefits, intermittent fasting is widely marketed to all.

But what many folks may not know is that most of the research that’s been done on fasting has been done on men. It’s only more recently that women are being included in the studies, thanks to pioneers in the field of women’s performance, like Dr. Stacy Sims.

She says,

If we look at intermittent fasting, where you’re holding the fast up til noon, or you’re having days of really low-calorie restriction, we see in active women it’s very detrimental.

There are exceptions to this, of course, due to various health conditions, but in general, active women should think twice about jumping on the intermittent fasting bandwagon.

While I was doing the research for this blog, I realized I had been “accidentally” fasting. I wake up at 5am, usually have a training client, or get in my mobility and stretching, feed the dogs, and take them on a long walk. I don’t eat anything until I get settled in at work around 8 or 9am. I’m not holding a fast until noon, but withholding food for 3-4 hours after waking up isn’t good for cortisol levels. I’ll touch on that more later in this post, and also tell you what I have now started eating immediately after I wake up.

Let’s look at some of the reasons why fasting doesn’t work well for most women, and what to do instead.

Metabolic Flexibility

Women are inherently metabolically flexible. We have more oxidative muscle fibers compared to men. Those are the ones that allow us to go long and slow. This is why it’s counter-productive for women to do zone 2 exercise, and also why it’s unnecessary for us to try to become more metabolically flexible by fasting.

Cortisol

In a recent blog, I talked about how high intensity training lowers cortisol (a stress hormone) in women and helps achieve a healthy body composition. When in a fasted state, we aren’t able to hit the intensity levels required of true high intensity in our workouts. Which means we don’t get the associated benefits. Also, both fasting and fasted workouts increases the stress on a woman, which causes an increase in cortisol. We are shooting ourselves in the foot when we fast (which raises cortisol) and can’t achieve high intensity intervals (which lowers cortisol).

Unlike men, a woman’s cortisol peaks about a half hour after waking up. Fasting adds to the stress. So withholding food for more than a half hour upon waking can cause more cortisol spiking as well as thyroid dysregulation and disrupted endocrine function. And to top it all off, caffeine makes it worse!

There are so many women waking up, not eating, maybe having just coffee, and working out. That was me for years, and like I was saying earlier, until very recently, I was withholding food for several hours after I got out of bed. It can be challenging if you’re not very hungry first thing in the morning. But if you can get in around 15 grams of protein and maybe a small amount of carbs right away, you will be doing yourself a huge service.

Here’s what I have first thing in the morning (even though I’m not hungry):

Instant Mushroom Coffee

1 scoop of whey or collagen protein

Drizzle of maple syrup or honey

Then I have my normal breakfast at 8 or 9am.

This small tweak to your daily routine will signal to your brain, “Hey! There’s some fuel coming in.” And that will result in less stress, less thyroid disruption, better cognition, energy for workouts, and simply better preparedness for the day ahead.

Age

As women get older, fasting becomes even more detrimental. Peri-menopause and menopause are an added stress. Avoiding low energy states by fueling with enough nutrition at the right time is key.

Finally, let’s discuss what proper fueling looks like.

What to do instead of intermittent fasting

Eat in accordance with your circadian rhythm. This is essentially “normal” eating of breakfast, lunch, and dinner. Plus, eat within 30 minutes of waking up, and fuel up before (and after) workouts.

If you’re a female and have done well with fasting, I will leave you with another quote from Dr. Sims:

How much better would you be if you were to actually pay attention to your circadian rhythm and fuel according to the stress at hand?