Does IF Affect Men and Women Differently?

04.09.2018 |

Episode #8 of the course The beginner’s guide to intermittent fasting by Theo Brenner-Roach


Good to see you back.

Today, we’re looking at whether IF affects men and women differently.

I’m going to go right ahead and tell you that it does.

Now, before you close your web browser and swear off IF, hear me out.

Yes, it is true that IF affects women in a different way than men, BUT that doesn’t mean women can’t use as a successful weight loss tool, way of eating, and/or lifestyle.

It just means there are things you need to be aware of, some modifications you may need to make, and of course, some situations where you shouldn’t use it all.*

Let’s look at the research.

Now, a quick caveat: As with much of the existing research done on IF, these studies have only currently been carried out with animals.

As such, the results can help us draw some conclusions about how it would affect humans. However, until studies are conducted with humans, we do not know definitely what the results will be.

That being said, I would always suggest you err on the side of caution.

One study conducted in rats found that after 10-15 days of fasting, the female rats’ hormones (responsible for appetite and reproduction) were far more—for lack of a better term—“out of whack” than the males. [1]

In fact, fasting in female rats lead to a reduction in ovary size.

Another study found that fasting altered levels of ghrelin and leptin (the hormones that regulate appetite and feelings of satiety) in both men and women across a spectrum of weights. [2]

Knowing what we now know (however limited) raises the question: Should women use IF?

The honest answer is that, considering how much we still don’t know about fasting, you should proceed with caution and use a modified approach.

This means:

• not fasting for more than 24 hours at a time if using weekly fasting

• using a 12-14-hour window when daily fasting (can be built up to 16 hours over time, depending how you react)

• ensuring you stay hydrated during fasting periods

• starting out slowly and building up the level of exercise on fasting days

• preferably training after breaking your fast on training days

• trying a day-on, day-off fasting approach (fasting for 12–16 hours on your “on” days)

Of course, if anything doesn’t feel right (anything at all) or you notice unexpected changes when fasting, then stop right away and re-adopt a “normal” eating pattern.

*The situations where you shouldn’t use fasting at all:

• if you’re pregnant

• if you suffer from an eating disorder

• if you have sleep problems

• if you are chronically stressed

• if you’re brand new to diet and exercise

As with all things fitness, if you’re ever unsure, then you should consult your doctor before starting intermittent fasting.

I know this lesson seems a bit scary, but it wasn’t written to scare you; instead, it was written to try and give you the full picture so you can make an informed decision based on your own personal circumstances.

Many women have used IF and gotten great results, but it’s not for everyone, and you shouldn’t feel any pressure to do it if you don’t want to.

Join me again tomorrow as we go through frequently asked IF questions.

See you tomorrow.


Recommended book

Burn Fat with The Metabolic Blowtorch Diet: The Ultimate Guide for Optimizing Intermittent Fasting: Burn Fat, Preserve Muscle, Enhance Focus and Transform Your Health by Jay Campbell



[1] Intermittent fasting dietary restriction regimen negatively influences reproduction in young rats: A study of hypothalamo-hypophysial-gonadal axis

[2] Fasting and postprandial levels of ghrelin, leptin and insulin in lean, obese and anorexic subjects


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