I first learned of Intermittent Fasting (IF) from The Secret Life of Fat. In it, Sylvia Tara described how she used IF in her arsenal of tactics to reduce body fat and increase lean muscle mass. This sent me of on a Quest for Fasting.
I found that in addition to longer overnight fasts like Dr. Tara used, practitioners defined a variety of IF routines.
There are also 5:2 fasts, where you eat for five days and then fast (or calorie restrict) for two days. And a monthly variant, where you calorie restrict for 5 days a month.
Every other day fasts alternate eating and fasting days. One routine employs a 24-hour fast (from the end of dinner on Monday until the start of dinner on Tuesday). Another option is to alternate eating days with 36-hour fasts (from end of dinner on Monday until breakfast Wednesday). Clearly, there is an infinite variety of protocols.
What a difference a day makes
One fasting fact really struck me: the liver stores enough glycogen to supply the body with its glucose needs for at least 24 hours after feeding.
That forced me to think about why we eat when we do.
It’s natural to think about our food needs on a daily basis. The day is an obvious cycle for us Homo sapiens. Because of this, we think about our Daily energy needs — such as the Daily Minimum Requirements. This leads us to plan and eat in daily “chunks.” Each day we want to meet our calorie and nutrient goals. Then the timer resets overnight and we start over the next day.
But is this daily planning optimal? Worse, is it detrimental?
Let’s imagine, for kicks, a shorter timeframe. What if the way we thought about eating, from our vocabulary to the planning, research studies, and recommendations were hourly instead of daily? We wouldn’t talk about needing 3,200 calories a day, but rather about getting our 200 calories per waking hour. And we’d eat that way. Planning each hourly meal. That’s right, lunch every hour!
Sure, that’s kind of absurd.
But is our daily framework causing a version of this same “eating too frequently” problem? Turns out research supports this conclusion. We simply don’t need to eat every day. I’ve already mentioned that we store enough to supply our glucose needs for twenty-four hours without eating again. But what else justifies spreading out the eating?
What’s the downside of constant eating?
Insulin response is a big factor here. Near constant eating, with a short break to sleep, never lets insulin levels and the important follow-on processes fully reset. Think of those NiCad rechargeable batteries. When you don’t fully drain them all the way before recharging, what happens? Their performance degrades.
There’s an evolution-versus-modern-life dynamic at play here. Between seasons, droughts, fires, monsoons, migrations, and other forces of nature, foods weren’t always available in abundance all year in our pre-history. Three square meals a day (plus some snack bars) was a luxury that just didn’t come that often. Thus, natural selection has left us with systems that are attuned to packing away food (as fat) for our use in the down times.
Think about it. If not eating for a day made us lethargic, light-headed, and dysfunctional, how would we ever have survived as a species? The first drought or winter season would have killed us all.
When we feed all the time, we disrupt the body’s store-and-release process. Our constant eating barely taps our system of stored energy (fat). Like that rechargeable battery, we’re draining a little and topping off every day. And never letting the full system get exercised.
That’s in the best of cases. In the worst case, constantly high insulin levels lead to insulin resistance which cascades into a host of well-known issues like obesity and diabetes.
The modern response to putting on weight, though, has been to limit our daily caloric intake — trying to manipulate the calorie input and output: deficit to lose weight, balanced to maintain weight.
Obesity trends suggest that this doesn’t work. In fact, constant eating at reduced calories triggers different responses than does not eating all. This is the well-known metabolic slow-down and other effects. Fasting is potentially a more evolutionary approach to managing calories and energy supplies with the way our bodies are designed to work, without the side effects of daily calorie restriction.
Better insulin management is just one benefit fasting for longer periods. Studies show improved functions from memory to concentration, to physical agility.
But fasting is sooooo uncomfortable!
With the idea of working towards an every other day routine, I started with a single 24-hour fast. Like most people, I didn’t know what I was in for. Fear of hunger and discomfort can make fasting hard to start.
My initial 24-hour fast was tough. No denying it. I couldn’t stop thinking about fasting, which of course kept me focused on food — or the lack thereof. I got headaches and a little weak-kneed. But I made it.
Several days later, I fasted again. This time it was much easier. And easier again two days later. Now I’m on an every other day 24-hour fast.
(A side benefit of the 24-hour routine: you don’t skip a dinner, so it’s easy to work into family or social life.)
Hunger is a big fear for anyone trying to fast. With hunger, though, you quickly realize something: it’s more in your habits than in your gut.
I noticed that much of the hunger cycle is about habit. For what seems like forever, I’ve had a coffee and a snack when I got to the office. Like Pavlov’s dog, getting to my desk was like a bell ringing. My brain told me it was snack time. Once you break these habits and change the stimuli, it is much easier. (See the tips above.)
What about exercise? Not a problem. I’ve been able to do my usual high-intensity-interval-training (HIIT) routine during fast days without a hitch. You have to feel it to believe it: you will not be lethargic or hungry on fast days. And despite the common wisdom, you will not start “burning muscle” when you fast. The body protects the brain first and the muscles second — remember, you need both to find that next meal in the wild. If you do resistance training, you can build muscle on a fasting routine.
So, when do we eat?
The research, and my experience, is starting to show that the answer is: far too often.
Disclaimer: I’m not your doctor. I’m not anyone’s doctor. This material is for information purposes only. Speak with your medical professional before starting any diet or exercise program.