diets · eating

Intermittent fasting and why it might not work as well for women

You’d have to be living under a rock not have noticed the latest diet trend, intermittent fasting.

It’s gone from making the rounds in the Paleo community (see Intermittent Fasting And The Paleo Diet) to mainstream with the 5-2 diet. See British 5:2 diet craze heads to the US. See also When you eat key to intermittent fasting (CBC).

The basic idea of the 5-2 version is that you “fast” for two days and then eat whatever you want for the remaining five. It’s not strictly speaking an actual fast because you do eat about 500 calories on the “fast” days.

There are many versions of intermittent fasting (or IF as many fans call it) from some that sound just like skipping breakfast, to others that have a more complicated structure throughout the week, to some that are geared to a very specific purpose such as avoiding jet lag.

The evolutionary basis of this approach to eating seems obvious. Humans have evolved to do well in feast and famine conditions. The problem with the contemporary North American diet is that it’s all feast, all the time. Many cultures around the world practice fasting and seem to suffer no ill effects from periods of fasting, followed by periods of feasting.

It’s striking how much IF deviates from the regular feeding, three meals + two snacks, of most other nutritional plans for athletes, including fitness competitors and body builders. On those plans you eat regular small meals, not going more than three hours without food.

But arguably the fasting habit isn’t for athletes. As you might imagine there’s been controversy over this. For the argument against IF for athletes, see here. The argument against relies on the large amount of data we have on the performance of Muslim athletes during Ramadan. Short version: athletic performance suffers. Also athletes need fuel to train. See that argument against here.

And of course, some athletes and coaches think it’s terrific, if done right, read more here if you’re interested.

Regardless most advocates and fans of intermittent fasting don’t have athletes in mind. The 5-2 diet is described as being perfect for the average person, no big changes in what you eat required, except of course on the two fasting days.

Is this just the latest fad diet? You should read what Tracy thinks about fad diets and the meaning of success here.  Does it work? Again, as Tracy says that depends on what you mean by work. She’d likely tell you to try intuitive eating instead. Intermittent fasting is kind of the opposite of intuitive eating. Rather than noticing and hunger and eating when you’re hungry, on a fasting diet you follow the clock, not your stomach. You learn to notice hunger and then ignore it.

There are lots of versions of IF out there.  Anthony Mychall does the Warrior Diet–one meal a day. He writes about it in this blog post, How to Start Intermittent Fasting and Kick Hunger Aside. How to cope with hunger? “The best way to forget about hunger is to literally put yourself in a position to forget about hunger. Keep active during your fasting window and put yourself in a situation where you can’t eat. Hell, sleep in if you have to.”

What about more extreme versions? In Inhuman Experiment: An experimenter in search of prolonged youth we read about another IF propocol. This one requires 24 hours of fasting as it’s based on alternate day feeding, called ADF, of course. See the blog post, Intermittent Fasting: Understanding the Hunger Cycle for more about hunger: “The feelings of hunger during intermittent (24 hour) fasting vary with time. The one thing to keep in mind is that, in my experience, the most difficult part is near the 20th hour into the fast. That’s when the hunger is replaced by a general lack of energy and focus. This feeling will, however, pass in an hour or so, after which fasting becomes much easier again.”

I’ve often thought of intermittent fasting as one tool in the careful eater’s bag of tricks. I do a version of IF I suppose (though I’ve never called it that) when I decide to not eat after dinner, thus lengthening the period in the day when I go without food. I do this on days when I’m not working out in the evening. I go to bed a little bit hungry but since I always wake up hungry no matter what there doesn’t seem to be any other change in my desire for food.

A few years ago on the advice of a personal trainer I experimented with morning workouts on an empty stomach but that was a bit of a disaster. See comments above on waking up hungry! Halfway through my morning run I was prepared to go knock on doors in search of breakfast.

I’ve had more some success with eating lots less when I travel. It’s a good time to experiment since the food options are crappy and expensive. I haven’t tried IF as a way of combating jet lag though I might the next time I head to England or British Columbia.

On jet lag and fasting. read more here:

But one thing seems clear about these various eating schemes, your mileage may vary: what works for some doesn’t work for others. If regular  intermittent fasting is successful for you, great, but there are concerns it doesn’t work as well for everyone and very specific concerns that it doesn’t work as a nutritional strategy for women.

I read Shattering the Myth of Fasting for Women: A Review of Female-Specific Responses to Fasting in the Literature and was shocked that for all I’d heard IF touted as good for people, most of the research supporting IF had been done on men. Surprise, surprise. For the effects of fasting specifically on women you need to read about studies with rats and mice, and the news isn’t good. Women, it seems (well at least female rats and mice) don’t get the same benefits from fasting and they suffer some additional ill effects.

Yet, I’ve had intermittent fasting recommended to me by several young men, heavily involved in fitness and nutrition.  In light of these experiences, I was thrilled to read a terrific rant (she gives the best rant) by Krista Scott Dixon, at Stumptuous.

In “The First Rule of Fast Club” she  rants about and aims fury and righteous rage in the direction of lots of things including the following: why intermittent fasting may not be the cure all for women’s weight woes, why in general what works for young men won’t work for women, and why women shouldn’t listen to young, thin, male personal trainers.

“The first rule of fast club is: Don’t talk about fast club.

The second rule of fast club is that skinny guys no longer get to tell me what to do. (Although I love you guys. You look so cute with your pants falling down!)

I come not to bury young male ectomorphs, but to praise them. In fact, I married one. They are a fascinating species. I have observed my own specimen for years, like Jane Goodall amongst the chimps.

Here are some interesting facts about these wonderful creatures.

1. Many of them can live on fumes. Craving neither food nor drink, these hominid hummingbirds apparently draw nourishment from the air. They sup on dew and dine on dust.

2. When they are stressed out, they don’t eat. Actually, when they aren’t starving, they don’t eat. Which is to say, most of the time. Can you believe not eating when you’re stressed? I know! Ha ha! Crazy! I keep trying to explain to my specimen that giving a loaf of bread a butter enema then dipping the whole thing in chocolate and rubbing it all over your esophagus will always make you feel better. Thus far I have failed to convince him.

3. When they do eat, it doesn’t seem to matter. Have you seen the food these guys can put down? It’s like they encode for some MAKE_ABS1 gene. In their bodies, somehow cookies turn into tummy bumps.

4. To lose weight, they do crazy shit like give up drinking so much beer. I hear women from all over the globe gnashing their teeth at their partners’ superhuman abilities to get riptshizzled with no effort. I’ve been busting my ass and I lost 1 lb in a month! That jerk’s doing my nutrition plan along with me and he’s lost 40 lb in the same time, just by eating one less strand of spaghetti a day! I hate him!

I hear ya. My home dinner table conversation sometimes goes like this.

Me: Ugh, I feel the estrogen demons again. I feel like an inflated wet sponge. The only thing that fits me is the Snuggie my grandma gave me last Christmas.

Him: I don’t feel so good myself. I had a whiff of anxiety today and dropped 5 lbs. Then my shirt tore itself on my abs.


There there ladies. Cry it out.

And here is point #5, which may be the most obvious:

5. They are not us.”

Go read the whole thing here.

Here’s a very useful resource if you’re thinking about giving intermittent fasting a try: Precision Nutrition, Experiments in Intermittent Fasting.

Have you tried Intermittent Fasting? What do you think? How did it make you feel?