When I was just getting started with the whole health & fitness thing a long time ago, I bought into a lot of the conventional wisdom surrounding exercise and nutrition, and I, like most other people, had heard about the vital importance of eating an early breakfast. Even though I wasn’t hungry when I woke up in the morning, I remember “forcing down” canned tuna, eggs, whole grains, and other foods shortly after getting out of bed “to jump-start my metabolism” and “ensure optimal energy levels throughout the day”. It wasn’t until I started leaving conventional diet wisdom behind in favor of ancestral health principles, evolutionary biology, and the “real science” on nutrition that I realised how flawed this strategy was.
Intermittent fasting: The evolutionary norm?
From an evolutionary perspective, the idea that “breakfast [shortly after awakening] is the most important meal of the day” clearly doesn’t make sense. In the modern, industrialized world we have easy access to cheap and calorie-dense food at all times, but for hunter-gatherers and traditional, isolated people, the situation is very different. For many hunter-gatherers, most of the daily energy is taken in at 1-2 meals, often late in the day. Of course, they will eat leftovers from yesterday earlier in the day if there is any and snack on whatever fruit, tubers, and other foods they find, but in general, it’s safe to say that their meal pattern is very different from what we consider “normal” in westernized societies. Over millions of years, the human genome was chosen by natural selection for ancestral natural environments. For our ancient ancestors, fluctuations in food availability/intake and intermittent periods of fasting were a natural part of life.
I might do a lengthy post on the science of intermittent fasting in the future, but today, I just wanted to put up a short description of what I’ve been doing lately. For the last couple of years, I’ve typically eaten my first meal of the day around 10 a.m., which is a couple of hours after I wake up, and my last meal of the day around 8-9 p.m. I feel this has worked well for me, but lately I figured I might mix things up a bit so I pushed the first meal 2-3 hours forward, to 12-1 p.m, basically shortening the feeding window to approximately 8 hours.
Since I’m used to eating a late breakfast, the change to now eating my first meal at around noon wasn’t as big as it is for people who come to this form of intermittent fasting after being used to eat breakfast early in the morning. However, the 2-3 hours do make a difference; the most apparent one being that I find it easier to stay lean. I also feel that my body responds well to having a longer break in between sessions of food intake.
I’ve always been an advocate of intermittent fasting for those who want to lose fat and/or have trouble keeping their body weight down without having to restrict calories. However, on the flip side, for someone who does a lot of heavy strength training and have trouble eating enough food to build muscle, intermittent fasting isn’t necessarily the way to go, as it can be hard to get as much calories as you need during the relatively short feeding window without stuffing yourself, choosing less than optimal sources of calories, and/or getting too little vegetables and fiber into your body.
I’ve also started doing fasted training in the morning. Prior to these last couple of weeks, I never did anything more strenuous than some low-intensity activities such as walking and light running on an empty stomach, as I had gotten it into my mind that I would get subpar results from doing heavy strength training, sprinting, etc. in a fasted state. I guess I haven’t been able to fully leave all of the conventional wisdom that was imprinted in me during my early years of strength and soccer training behind. Also, the fact that what I’ve been doing for the last couple of years (a balanced meal approximately 2 hours before a workout) seems to have worked for me have clearly kept me from making the leap to fasted training.
While I have to give fasted training some additional weeks before saying anything conclusive about the pros/cons, I can already say that I’m surprised by how well it works. I believed my energy levels would take a greater hit from not having a pre-workout meal, but as long as I eat well the day before, I seem to be doing just fine. One of the things I really like about fasted training is that I don’t have to worry about timing my day so that I get to eat a meal 2-3 hours before my workout. Fasted training also comes with several potential benefits related to protein synthesis, muscle growth, etc. that I might get into in a future post.
When we look at diet and exercise from an evolutionary perspective, it quickly makes sense why we are so well-adapted to train in a fasted state – and why fasted training is linked to many health benefits. Hunter-gatherers are very physically active, and they often hunt and gather on an empty stomach, typically early in the day. Since the ability to be physically active while in a fasted state was so essential to our ancient ancestors, it doesn’t come as a surprise that natural selection has equipped us with the capability to not only endure fasted training, but to perform well in a fasted state. However, we have to keep in mind that the type of physical activities performed by our Paleolithic ancestors differed from what a lot of us do in the gym today, and that training on an empty stomach obviously isn’t optimal for every type of activity/workout.
Needless to say, I’m a big proponent of a Paleolithic lifestyle, including Paleolithic-style diets and ancestral physical activity patterns. Occasional periods of fasting is a natural component of this way of living. In the future I might take the time to write a lengthy post on fasting, but in the meantime, there are plenty of great online resources you can check out (e.g., leangains.com).
Do you have any experiences with intermittent fasting? Then I would like to hear from you in the comment section below.