intermittent fasting: what it is & if it's for you

fasting? isn't that like...starving or something that monks or super religious people do?

well, yes and no. some people call it a "diet;" others say that it's just a natural way of life that our ancestors aka the hunter-gatherers had to practice because there was no way they had a fridge full of snacks handy for whenever they felt like eating.

what it is, in a nutshell, is that you only eat during a certain time window and you fast for the other hours of the day.

well-known people from Hugh Jackman to Tim Ferriss swear by it. there's a myriad of health benefits, which I'll get into later, but like all other ways of eating / living, there are some downsides as well. interested? good. we'll get into it.

what it is: in more detail

there's a couple of different ways that people like doing intermittent fasting. it can also be called "time restricted feeding," and if you're doing it by day, then you break the day down into fasting hours and non-fasting hours.

the most common ratios (fasting : non-fasting) are: 20:4, 18:6, 16:8, and 12:12. I personally do the 12:12 and have accidentally done the 16:8 if I'm traveling, super busy, or had a really large meal the night before, but the reason why I go for the 12:12 is that it's enough for me to truly listen to my body cues.

the 16:8 is the most popular one by far; Hugh Jackman follows that one (though that's not necessarily to say you should too).

there are also short bursts of fasting, where you don't eat for a day once a week or a month, the 5-2 method where you eat a low amount of calories (500-600) two days out of the week and eat normally the other five. for reasons that I'll go into below, I don't recommend this to most people, especially if you have a history of calorie restriction (sorry, might be a given but just thought I'd put it out there).

the benefits

so, why the f would you not eat? different people do it for a couple of different reasons.

1. it can improve focus and productivity

this study was done on mice — so huge disclaimer there — but it shows improved memory due to a reduction in oxidative stress in the brain, which can impair memory and increase brain aging. but other than that, it's become all the rage in Silicon Valley because people swear by the increased clarity.

2. it legit makes life easier

meal prep? worrying about your yogurt going back on the commute from home to work? all of the time spent prepping and worrying about food is drastically cut, allowing you to focus on things that matter more.

this is one of the reasons why intermittent fasting is popular among people who are considered "life hackers" (ex: Tim Ferriss); it's similar to successful people like Mark Zuckerberg and Barack Obama having a set uniform every day. with less energy expended towards worrying about smaller-picture things, you have more energy to devote toward big-picture things (starting or running a company).

3. it may improve health

there are a variety of metabolic benefits, but one key health benefit is that it reduces insulin resistance (aka improves insulin sensitivity). if you're asking yourself wtf that is and why it matters, I did too. basically, it lowers your blood sugar levels and can help prevent against type 2 diabetes. it can also help protect your gut microbiome, lowering inflammation (disclaimer — this study was done on fruit flies, but apparently they have a 61% genetic match with humans disease genes).

4. you'll lose weight

ok, this one seems like a given. but for people who are extremely obese, this can be a good way to do it. just because it's not a diet. you don't have to eat or not eat something. you only have to eat during certain time periods, part of which you're sleeping for. that makes it easy to stick to. in addition, it increases the oxidation of fat while sparing your muscles, making it easier for you to lose fat rather that muscle mass.

the downsides

there are quite a few obvious downsides to this, and I think it's important to address them.

first of all, like any health study, the research is not 100% solid. most studies are done on mice, not people; in addition, all people respond differently to different things because, like we all know, every body is different.

women especially receive less benefits and have more risks from intermittent fasting (though these are mostly for the fasting for a couple of days rather than the time-restricted feeding window form). if you are exercising a lot, already very lean, and have high amounts of stress, you can be at risk of becoming amenorrheic (losing your period).

I think this advice from Mark's Daily Apple sums it up beautifully:

Most of all, though, I’d simply suggest that women interested in fasting be cautious, be self-aware, and only do so if it comes naturally. It shouldn’t be a struggle (for anyone, really).

a more important topic to address is the psychological impacts of intermittent fasting. because, no matter what you call it, fasting is not eating. and if you have a history of disordered eating or calorie restriction, this can be an unintentional way to spiral back into old habits.

in this 2016 study of "healthy" women (i.e. women who did not self-report eating disorders), some women reported feeling a sense of achievement at abstaining from eating. for anyone who has experienced restriction, this sense of achievement is very similar to why restricting eating can be addicting.

if you ever find yourself feeling proud of yourself for not eating rather than finding that fasting sometimes allows your body to reset and takes less of a toll on your digestive system, STOP. talk to someone. think about why you feel this way, and, as always, feel free to reach out to me!

think it's for you?

so, cool — you think you want to try? here are a couple of questions you should ask yourself:

  • why do I want to do it? if you feel like you're 100% fine with how you feel right now, then is there really any reason to start this?
  • what do I want to gain from it? have some type of goal in mind.

here are my thoughts and advice:

  • listen to your body. if you wake up and you're starving, it might just be the increased cortisol in your system in the morning. give it some time. drink some tea or coffee (and most importantly, at least 8 oz of water); if you're still hungry after 30 minutes-1 hour, eat.
  • start slow. don't just jump into 16:8 right away, or full days of fasting right away. start slow and build up to it.
  • know your routine. intermittent fasting is the easiest when you're super busy and have a lot to do. if you're just sitting at home with a fridge full of food, it's likely that you'll snack from boredom. also, if you're exercising a lot, make sure that you're eating enough. 

other resources

Paleo Women Podcast : episode #119  talks about both long-term (fasting for more than a day or two) and intermittent fasting for women

Paleo for Women article: "Shattering the Myth of Fasting for Women: A Review of Female-Specific Responses to Fasting in the Literature"

Tim Ferriss' Tools of Titans: The Tactics, Routines, and Habits of Billionaires, Icons, and World-Class Performers book: this has a whole section on how different successful people go about intermittent fasting

Nerd Fitness article: "A Beginner's Guide to Intermittent Fasting"

Mark's Daily Apple has an entire series on fasting; here's the first article (the series is linked at the bottom of that post)