I stumbled across intermittent fasting (IF for short) by accident. In fact, I’d been using a form of IF for several years before I realized there was a name for it.
It started in 1999, when I got into the habit of going to the gym first thing in the morning before eating anything. I’d been reading Body-for-LIFE by Bill Phillips, and “fasted cardio” was one of the things he recommended.
The idea was to skip breakfast, train in a fasted state, then leave an hour after your workout before eating anything. So I’d go to the gym on the way to work, train and then eat something when I got to the office.
But then I quit my job and started my own business working from home. I’d fire up the computer as soon as I got out of bed, work for an hour or two and then go to the gym.
The main reason I did this was to avoid the rush hour traffic. But there was another benefit I wasn’t expecting.
The morning hours were highly productive for me. I found it so much easier to get into that “flow state” where you’re lost in what you’re doing and time seems to pass a lot faster than normal. As a result, I was able to get a lot more work done.
It seemed like a waste to spend my most productive hours of the day in the gym, or even to sit down and eat breakfast.
Gradually, the amount of time I spent working got longer and longer. I ended up going to the gym at around 11am, which would push my “breakfast” back to between 12 and 1pm. This is an eating pattern very similar to the one Martin Berkhan talks about on leangains.com.
Having used it for the best part of 15 years, here’s what I think of this type of IF.
IF is a very simple way to create the energy deficit you need to lose fat.
You just don’t eat breakfast, and then go about the rest of your day. That simplicity gives it a big advantage over most other diets.
The calories that you normally have in the morning are eliminated from the diet. This means that your calorie budget is distributed across fewer meals. As a result, those meals can be larger and more “normal” than your typical diet fare.
Because your feeding window is smaller than it otherwise would be, you also end up eating less often.
Back in the day when I worked at a gym, the early shift used to start at 6.30am. If I’d done the late shift the night before, this often meant getting by on just 4-5 hours of sleep, which isn’t enough for me.
But I still used to sacrifice 30-45 minutes of precious sleep time and get up earlier than I needed to. That was so I had time to make food to eat during the day. At the time, I believed (wrongly as it turns out) that I wouldn’t be able to build muscle if I went more than a few hours without eating anything.
The fact that IF lends itself to a lower meal frequency has a big advantage in the “time spent preparing and eating food” department. And I certainly don’t miss the smell of tinned tuna at five in the morning.
IF sits well with the current body of evidence on diet and weight loss.
We’ve known for a while that eating six versus three meals a day has no benefits as far as fat loss is concerned. We also know that IF performs just as well as continuous calorie restriction when it comes to preserving muscle while dropping fat. And that breakfast doesn’t affect your ability to lose weight whether you eat it or skip it.
You’d think that fasting would give you less energy. For me, the opposite is true.
As I mentioned earlier, my most productive time of day is the first few hours in the morning, especially with some caffeine inside me. Skipping breakfast doesn’t hinder my ability to get stuff done. In fact, I usually get a lot more done in the morning than I do in the afternoon after I’ve had something to eat.
When I started training first thing in the morning on an empty stomach I was worried that my performance in the gym would take a hit. Which it did at first. But after a few weeks of getting used to it, things got back to normal. I’m not saying that IF improved my strength. But it certainly didn’t make it worse.
Those are the things about IF that I like. There are also some things I don’t like.
IF started out as an effective way to free yourself from the various “rules” associated with dieting – eating six small meals a day, avoiding large meals at night, not skipping breakfast – most of which were largely pointless as far as weight loss is concerned.
However, the same thing is now happening in reverse, with some IF proponents preaching an equally pointless set of rules about what and when you’re supposed to eat.
You’ll also see a lot of nonsense from “biohackers” getting excited about how fasting raises growth hormone levels by 2000%, as if this is somehow of critical importance when it comes to improving your body composition (it isn’t).
There’s no magic about IF. It’s just a simple way to stay within your calorie budget for the day.
Like any diet, IF has the potential to go wrong. Some people eat so much during the “feeding window” that they end up in a calorie surplus rather than the deficit required to lose weight.
I’ve also heard of guys cramming the vast majority of their food intake for the day – sometimes in excess of 6000 calories – into a single evening meal.
IF normally goes hand in hand with a more “flexible” approach to dieting. But that doesn’t change the fact that a calorie deficit is still required if you want to lose fat. Nor does it mean that you can ignore the macronutrient composition of your diet and expect your results to be all that they could be.
There may be some health benefits associated with IF, which Bojan Kostevski has summarized here. But any superior metabolic effects compared to conventional meal patterns are based more on speculation than any hard evidence.
UPDATE: I got a lot of emails in response to this post, mainly from members of the breakfast police, who wanted me locked up in a prison cell before I could say anything else they didn’t like.
One guy in particular was angrier than the Hulk. He was extremely concerned about the “damaging consequences” that would ensue once knowledge of my eating habits spread across the Internet.
As I explain here, you can make a strong case for or against the importance of breakfast simply by ignoring the studies that don’t say what you want them to say.
And by breakfast, I’m talking about the first meal of the day, eaten within the first hour or two of getting out of bed, usually no later than 11am (as opposed to the first meal of the day that “breaks the fast,” which can’t be skipped and only delayed).
But forget about the research for a moment, and consider this.
Let’s say that during the week, you normally eat breakfast at 7am.
You have your last meal of the day at 8pm.
Which means that your overnight fast lasts a total of 11 hours.
The weekend rolls around, and you decide to have an extra few hours in bed, which pushes breakfast back to 10am.
In other words, your overnight fast is now three hours longer.
If the breakfast police think that delaying breakfast is a bad idea, they should be able to explain why.
What is it about those three hours of additional fasting that is somehow bad for you?
Why is 11 hours of fasting okay, but 14 hours of fasting isn’t?
What happens when you go on holiday? Or retire? Or win the lottery?
Should you abandon your lie in and get out of bed earlier? Or should you eat your dinner later?
Because if the breakfast police are telling everyone to eat breakfast, they’re effectively saying that the overnight fast shouldn’t extend beyond a certain period of time.
In which case they should also be telling us what time to eat dinner, and how long to spend in bed.
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ABOUT CHRISTIAN FINNChristian Finn holds a master's degree with distinction in exercise science, is a former personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine.