The hunter-gatherer lifestyle is definitely “in” right now.
There are several extremely popular diets out there at the moment that are all claiming to draw on our ancestral eating habits.
The obvious example is the paleo diet. Adherents claim to be eating as their paleolithic ancestors once did (and supposedly as our biology demands). They say that our bodies haven’t changed much in the last 40,000 years, so our diets should not be so radically different.
Another example is the carnivore diet. As the name suggests, this diet has people eating nothing but meat – usually red meat in particular. The idea is that our bodies evolved to prefer meat as a source of energy and nutrition. Proponents of this diet claim that it can do everything from curing metabolic diseases to shredding through bodyfat.
All of these “nostalgia diets” are fundamentally flawed in our opinion. They all draw on very shaky archaeological evidence (our paleolithic ancestors lived short, sickly lives) and baseless assumptions (not everyone in the paleolithic era ate the same way).
That said, one thing is for sure; our ancestors were definitely much leaner and fitter than we are today. It’s also true that the hunter-gatherer tribes that still exist today are much fitter, leaner, and generally more muscular than the average person in the developed world.
But we don’t think the explanation has anything to do with the exact foods they’re eating (lots of berries, tubers and nuts obviously do help).
We think a big reason why they are so lean and physically fit is because of when these people eat.
In our opinion, the fact that most hunter-gatherers will regularly go prolonged periods without eating is a better explanation for why they – and our ancestors – were so physically strong, fit, and trim.
Fasting is a very important feature of our ancestral diets, yet it is completely overlooked by the paleolithic diet, the carnivore diet, and every other diet supposedly mimicking our culinary roots.
Here we’re going to discuss the ways in which fasting can help with fat loss. There are several different benefits to fasting; eventually we’ll cover all of them. But for now, we’ll focus on the one that people tend to care most about – shedding body fat.
Fasting & Fat Loss – The Evidence
There’s a lot of evidence to suggest that fasting in some form or another significantly reduces body fat. Many clinical studies have specifically looked at fasting as a weight loss tactic in comparison to traditional “dieting”.
This one for example, found that restricted time eating (“intermittent fasting”) is effective for fat loss; at least as effective as continuous calorie restriction (without time restriction).
These results have been replicated in other several other studies – such as this one – all of which show clearly that intermittent fasting is an effective way to reduce body fat.
So we don’t really need to question whether fasting works.
The question is, how does it work?
Thankfully, the relationship between fasting and fat loss is well understood; we can easily explain why time-restricted eating promotes fat loss.
How Does Fasting Work?
What you eat is important. But when you consume food also has a huge impact on how your body uses the calories at its disposal. That’s because eating causes a dramatic shift in your hormone levels, and that changes how the body processes and stores calories.
When you eat, your body begins to digest, process, and use that food. It releases insulin, which shuttles the nutrients now floating around your blood to the places where it is needed. That could be to certain cells to fuel activity, to muscles to trigger repair, or to fat stores to save energy for future use.
Now, when your body has lots of food to use for energy and to carry out bodily processes, then it doesn’t need to raid its precious fat stores. So while your body is still processing food in your digestive system, and while it still has plenty in the blood for use as “fuel”, your body has no reason to dip into its piggy bank.
How this plays out chemically in your body is fairly straightforward.
When your body needs to access your fat stores for energy, an enzyme called hormone-sensitive lipase (HSL) kicks into action. This enzyme breaks down your stored fat into free fatty acids, allowing them to be mobilized for use as “fuel”.
HSL is completely inhibited in the presence of insulin.
When you eat food and you experience an insulin spike, HSL does not work, and you will not be mobilizing any fat from your fat stores.
Think of it this way: your body doesn’t want to use its fat stores, so if it doesn’t need to, then it wont. In order to start using up stored fat, you need to force your body to resort to its emergency reserves.
One way to do that is to completely remove insulin from your blood, thereby allowing HSL to do its job and start freeing up some fatty acids for use. And one sure-fire way to achieve that is to simply not eat for a prolonged period.
Fasting vs Caloric Restriction
Lots of people claim that fasting – and intermittent fasting in particular – is far superior to caloric restriction.
The reasons they cite are many and varied: more practical, greater dietary freedom, better muscle retention, etc.
While there is some credence to these claims, we’re only talking about intermittent fasting in the context of fat loss.
In that area, the facts are quite clear: there is no difference in fat loss results between caloric restriction and intermittent fasting.
There are lots of studies comparing fasting and caloric restriction directly. All of them say that there is no significant difference between traditional dieting and time-restricted eating: both work just as well as each other when it comes to losing body fat.
For example, the researchers behind this paper concluded that “Intermittent fasting thus represents a valid – albeit apparently not superior – option to continuous energy restriction for weight loss.”
You wont struggle to find other good, robust, peer-reviewed clinical trials showing exactly the same thing.
When it comes to losing body fat, then caloric restriction and intermittent fasting seem to be equally effective.
So which should you choose?
That depends entirely on you, what your specific goals are, and what kind of person you are. If you’re anything like us, then you will really struggle with caloric restriction, “clean eating”, and other traditional dieting techniques. We like to be able to eat what we want, and we like big portions. As such, intermittent fasting just makes sense for us.
We also want to build and preserve muscle mass as a priority. We all therefore need to be taking in sufficient calories per day to furnish that growth. Intermittent fasting gives us a way to reduce body fat without cutting back on the fiber, protein, or complex carbs that we need to stay healthy, strong and full of energy.
But you might be different.
Our advice would be to try both methods and see what works best for you. Let the scale tell you if it’s working. Fasting has been shown to have a number of benefits distinct from caloric restriction – such as enhancing healthy bacteria in the gut – so it might be worth trying at least once if you haven’t done so already.