At first, I dismissed it. Yes, it sounds like the newest health fad that will become obsolete within a year, but intermittent fasting (IF) keeps coming up. I can’t seem to get away from reading about the benefits of allowing your body to enter into “survival mode.” I kept hearing about increased energy levels and ability to focus while gaining muscle and lowering body fat percentages. Heck, even Nassim Taleb does it! And some of the claims are pretty impressive. Could it all be true? I’m not sure – but I’ll provide a brief overview of what it is for those interested.
Do remember that with any diet, fitness regime, or lifestyle choice, there is no one-size-fits-all strategy. Some things work for some people and not for others. The best thing to do is self-experiment and see how you feel. In saying that, here is the skinny on IF:
What is it? IF is not a diet. It is a pattern of eating wherein you limit your calorie intake to specific windows of time, usually going anywhere between 16 & 24 hours without eating. You generally eat the same amount of calories, but in a reduced time-frame.
Why do it? . Some people claim this volatile calorie intake schedule makes our bodies stronger (think Anti-fragile) and burn fat more efficiently. This is more similar to the sporadic eating schedules of our hunter & gatherer ancestors; they were not able to eat until they killed something. Seems reasonable. Here are a few of the modern-day claims:
- Lose fat: Your body goes through various states as it eats:
1. The “fed” state: when you begin eating (lasts for 3-5hrs). It is hard for your body to burn fat in this state because your insulin levels are high.
2. The “post-absorptive” state: lasts until ~8-12hrs after your last meal (body is not processing a meal)
3. The “fasted” state: it is much easier for your body to burn fat here because your insulin levels are low and your body must consume your own stored fat for energy.
- Increase focus: The science is less certain, but many people claim it.
- Simplifies your day: Less meals, less planning = less decision fatigue.
- Live longer: It is widely known that calorie restriction can lead to longer lives; however here is a study that shows the same effects from IF.
- Easy to execute: Psychologically, it is easier than dieting (if you want to lose weight)
- Reduce the risk of cancer? Here is one study that shows how alternate day fasting can reduce the risk of cancer and cardiovascular disease. There are other studies out there.
So what are the downsides? I’m still skeptical. Like many things, there is still a lot that we probably don’t know we don’t know. For people who do not want to lose weight, they may find it difficult to consume the same amount of calories in a shortened time-frame. The benefits seem to be limited for women – here are a couple articles: 1 & 2 on the difference for women. For young professionals and those who like to go out with friends, you may alienate yourself from time-to-time. The very good book “End of Illness” talks about the many benefits of having regularity and predictability to your schedules. There is a risk that IF adds adrenal stress and messes with hormones/Circadian Rhythms, which may hold some weight. Also, its not easy being hungry!
How do you do it? There are 3 main ways
1. Daily IF: Eat all of your calories in an 8-hr window every day (8hrs eating, 16hrs fasting, every day).
2. Weekly IF: Fast for 24hrs one day per week
3. Alternate Day IF: 24-hr fasting cycle, every other day.
This post was simply meant to pique your interest. Here are the best write-ups that I’ve found about IF so far.
- Nerd Fitness: The Beginner’s Guide to Intermittent Fasting (warning: a very supportive argument)
- Precision Nutrition: Experiments with Intermittent Fasting
I’ve started experimenting with it. Call it IF-extremely-light as I’m doing one 16-hr IF per week. It has been easier than I thought and I must admit, I’ve felt good. I plan to slowly bring that up and continue experimenting with it. At the very least, next time you skip a meal, perhaps you don’t have to worry so much! Happy reading.