Once when I was talking to someone about my book on aging and the actions that we can take to slow it, this person asked me what was my most important piece of anti-aging advice, if I had to put it in one sentence.
My reply: “Stop eating all the time.”
This piece of advice is also important when it comes to staying lean and/or losing fat.
The most robust (non-genetic) intervention known for prolonging the lifespan of lab animals is calorie restriction (CR). Animals that have their food restricted from 10 to 50% of that of fully-fed animals live much longer, in some cases 50% longer.
Many theories have arisen as to why CR increases lifespan. One theory is that CR results in less fat tissue, and that this is crucial to longer life.(1) Other theories have to do with repressed insulin signaling (2) and/or increased autophagy, the cellular self-cleansing process that rids cells of junk.(3) Likely all of these theories are related to each other mechanistically — you can’t have greater autophagy without reduced insulin signaling, which in turn leads to lower fat mass, for example.
I like to focus on autophagy, because this is a marker within our control to some extent.
Aging is characterized by a decline in the amount and amplitude of autophagy, which allows increased amounts of cellular damage and junk to accumulate.
Autophagy is strongly cyclical, rising and falling over periods of hours and days. Eating strongly decreases autophagy, and fasting increases it. I hope you see where I’m going with this.
If aging means less autophagy and more damage accumulation, and fasting increases autophagy, then fasting fights aging.
In fact, intermittent fasting is the most potent anti-aging strategy available.
Now, if we eat all the time, we never enter the fasting state and never up-regulate autophagy.
Eating constantly or every few hours, or “grazing” as it’s called, is one of the most potent pro-aging actions available.
So stop eating all the time.
How often does eating have to be to constitute “all the time”?
To answer that, it’s helpful to look at what people did in the old days — you know, about 40 years ago, before the obesity epidemic started. Or even more so, before the era of industrial processed food and cheap fast-food restaurants.
It was common for people to fast for 12 hours daily, from dinner in the evening until breakfast the next morning. Many mothers often told their children, “Better eat your dinner because there won’t be anything until breakfast.” My mom did anyway.
As we age, insulin resistance increases, fat tissue accumulates, and autophagy declines.
But we can fix that to a great extent by fasting longer than 12 hours. By 16 to 18 hours, autophagy proceeds at a rip-roaring pace, clearing out damage making cells young again.
Obesity likely has many causes, all working together to produce it.
But one factor that doesn’t get enough attention is the frequency with which we eat. When we eat constantly, insulin never drops by much, and so lipolysis, the exit of fat from fat cells, can’t take place.
Contrary to popular belief, energy expenditure has not decreased in recent years and is similar in modern people to that of wild, non-overweight, mammals.(4) Westerners seem to expend the same amount of energy as hunter-gatherers.(5)
Hunter-gatherers of course eat different food from Westerners, but they also don’t eat all the time.
Furthermore, energy expenditure can increase with fasting.(6)
And our distant ancestors way back in the 1960s had a far lower rate of obesity while eating, in general, lots of crappy food. They weren’t interested in “health food”, but largely managed to keep obesity at bay anyway.
The lesson is clear, to stay lean and/or lose weight, stop eating all the time.
Current mainstream advice on losing weight seems to be to eat constantly in order to keep your metabolism up. (I say “seems to be” because I avoid reading mainstream health advice where possible — most of it is bad for health.)
In fact, the admonition to eat constantly, or graze, is the kind of BS weight-loss advice that’s perpetuating the obesity epidemic.
Can you really lose weight by eating more often? No, you can’t. Not only will someone who eats constantly fail to lose much weight, but he’ll promote aging and the diseases that go with it.