The skinny on intermittent fasting

In a cafe a short stroll from his inner-Sydney apartment, Phil Chant is in high spirits.

There’s a bunch of numbers he’s eager to show me. From a folder he pulls out the results of his latest DXA scan (that’s Dual-energy X-ray absorptiometry, technology that can tell you everything you’d ever want to know about your body’s composition, such as the percentage of your right leg that’s comprised of muscle).

“Take a look at this,” says Chant with the urgency of a disaster-movie scientist. Except in this case the news is good. As a matter of fact, Chant is busting over how a new-old approach to eating called intermittent fasting (IF) has reshaped his body.

“Just in the last two months I’ve put on 3.3 kilograms of muscle while losing 1.3kg of fat,” says the 47-year-old marketing manager.

Rifling through pages of data, Chant points out that within four months of starting intermittent fasting his body-fat percentage fell from 17.7 to 10.9. Best of all, the technique has extinguished virtually every trace of fat from his once-conspicuous stomach, the body part that had equal parts embarrassed and disgusted him for most of his adult life. “The guy doing the scan was stunned,” recalls Chant.

IF encompasses multiple dietary strategies sharing a common premise: that going a little longer than you’re used to without food is good for you.

Perhaps the best-known type of IF is the 8-Hour Diet, where you do all your eating for the day within an eight-hour window – say noon until 8pm. The rest of the time you fast. The Warrior Diet narrows the feeding window to four hours in the evening, though very light grazing is permitted during the day.

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Chant’s method (known as Eat Stop Eat) is to abstain from all food for one or two 24-hour periods a week. Let’s say you’ve just eaten breakfast. If it’s a fasting day, then the next time food will touch your tongue will be breakfast tomorrow.

Why would you want to try IF? A lot of reasons, but top of the list could be fat loss. Note we said fat loss, not weight loss. You could drop a lot of weight via IF, but the point is, if you do this right, you’ll be zeroing in on fat while standing every chance of preserving (or even building) hard-earned muscle mass.

In other words, IF could be for you whether you’re overweight and just straight up want to drop kilos. Or if you’ve already sculpted a decent physique that would be unveiled or finished by shedding a coating of fat.

Beyond aesthetics, IF could help protect you from various diseases – including the big killers heart disease and cancer – while sharpening your concentration and lifting your performance at work.

“Should we all be fasting?” asks Brad Pilon, Canadian author of the e-book Eat Stop Eat. “For the vast majority of us, the answer is a resounding yes!”

At this point we should warn you that elements of IF don’t mesh with the orthodoxy. More than that, this story contains ideas that contradict advice we’ve been giving you in this magazine for years – things like how important it is to eat breakfast and to consume protein shortly after a workout, and how it’s better to eat five small meals a day than three bigger ones. It’s also highly likely that in subsequent issues of Men’s Health we will revert to more conservative positions on issues of nutrition.

With a hint of sheepishness, though only a hint, what we’d say about any self-contradictions is that the quest for knowledge is unceasing and takes innumerable twists and turns en route to certainty. We’d also say that we need to be open to new ideas – and that IF is definitely one of the more interesting ones.

The science of overeating

Standing in a dark conference room at the Salk Institute for Biological Studies in La Jolla, California, Satchidananda Panda is at the epicentre of a research movement that has rocked conventional weight-loss thinking to its core. Gesturing towards a big-screen display, Panda clicks over to a pair of maps. The one on the left shows the varying degrees of darkness and light pollution in the night sky over the continental United States. The one on the right: diabetes incidence, county by county, among the US population. The charts have been adjusted to control for the greater population numbers in city areas, but still, the two are mirror images of each other.

“Where there are more lights,” he says, “there is more diabetes.” Those aren’t refrigerator lights depicted on the night map, but they might as well be, given the effect on all of us.

Panda goes on to explain what he believes may be happening: “My hypothesis is that staying up and eating late may be the cause. [Early on] we didn’t know how to use fire. In the daytime, human beings would hunt something, eat something; but in the nighttime they had to protect themselves against predators. It was only about 200,000 years ago that we learned how to control fire, and only a few people could use fire to stay up past sunset. For the past 50 years or so we’ve been staying awake late into the night. That’s when we see the rise of weight problems.”

He has a theory about the mechanism behind it: the advent of artificial light has also led to an artificial extension of our feeding times. Our circadian rhythms have a natural stop sign built into them, and we run into that sign almost every day. Think about how you regularly sidle up to a bowl of ice-cream while watching late-night TV, or stop at Macca’s for a late-night drive-through snack. Modern technology has created an artificial daytime for us, and we’re filling it up with meals four, five and six. That extended eating interval throws our digestive system off-kilter and messes with the many hormones and enzymes that manage it. Our bodies can’t process the food we eat, and those kilojoules end up where they shouldn’t – around our bellies.

Not convinced yet? Hang in there.

Panda’s laboratory devised an ingenious study to test his ideas on mice. The mice were divided into two groups and put on the same high-kilojoule, high-fat diet: one group was given the freedom to eat anything at any time of day. The other mice could eat as much as they wanted but only within an eight-hour timeframe. The study went on for 100 days. Guess which group was plumped up?

“Simply limiting food intake to eight hours gives you all the benefits – without having to worry about food intake,” explains Panda.

For years we’ve been told, “You are what you eat.” Turns out, we are when we eat, too.

Beat the flab

What Panda and his voluminous vermin are discovering isn’t entirely new. For several years, researchers have also seen remarkable weight-loss results in people using some variation of intermittent fasting.

Don’t let that f-word scare you. In the case of the 8-Hour Diet, fasting isn’t about denying yourself anything. Instead, it’s about simply eating what you want but staying within a sensible eight-hour window. Eat Stop Eat extends the no-food period to 24 hours, but only once or twice a week.

The fact is, you’re already fasting on a daily basis. Think for a moment about the word “breakfast”. It is exactly the sum of its parts – the point of the day at which you break the fast you started whenever you stopped eating the night before. In the simplest terms, the 8-Hour Diet is a way of extending the period between your last snack and your “break fast,” giving your body the chance to burn away your fat stores for the energy it needs.

And burn them it does. Consider this 2007 American Journal of Clinical Nutrition study: researchers divided study participants into two groups and had each group eat the same number of kilojoules – enough for them to maintain their weight. The only difference: one group ate all their kilojoules in three meals spread throughout the day, while the other practised intermittent fasting, eating the same number of kilojoules, but in a restricted time frame. Among the results: participants who ate in a smaller window of time had a “significant modification of body composition, including reductions in fat mass”.

Part of that fat burn comes simply from the body’s searching for energy and finding it in your belly. But part of it is also from a surprising source: according to Panda’s research, restricting the time period during which you eat makes your body burn more kilojoules throughout the day.

That’s right: The longer you feed, the lazier your metabolism becomes. But fit your food intake into an eight-hour window and your body steps up to the crease, burning more kilojoules day and night. And new evidence shows that weight loss is just the beginning of intermittent fasting’s range of health benefits.

Beat diabetes

Type 2 diabetes may well be Western societies’ nastiest plague, one that can simultaneously increase your risks of heart disease, stroke, hypertension, sexual dysfunction, blindness, amputation and kidney disease. Yes, it’s that bad. But fasting, as it turns out, can help prevent the disease from even developing.

In a study at the University of Copenhagen, researchers found that when men fasted every other day for two weeks, the insulin in their bodies grew more efficient at managing blood sugar.

And Benjamin Horne, director of cardiovascular and genetic epidemiology at the Intermountain Medical Centre Heart Institute in Utah, has also studied people who stretch out the time between meals. His conclusion: “We found something we did not anticipate, which was that people who fasted also had a lower risk of diabetes. We looked at just regular diabetes, but we also looked at body mass index, baseline glucose and glucose during fasting, and found that people who have been routinely fasting over the years have a significantly lower body mass and blood sugar.”

It’s the physical cliff of our age, and it may be that we’ve now found a simple way to keep from plunging over. Take regular breaks from eating and watch your waist and risk shrink.

Beat heart disease

Imagine eating whatever you want (within reason) and being able to slash your heart attack risk just by watching the clock. That was the promise offered up by a study published in 2011 in the American Journal of Cardiology. The researchers found that people who followed a regular fasting plan – stretching out the period between their last meal today and their first meal tomorrow to 24 hours – enjoyed a 58 per cent lower risk of coronary disease, compared with those who didn’t follow this plan. This backed up the findings of a 2008 study of nearly 448 people, who demonstrated a similar ability to sidestep the cardiac ward with the same eating strategy.

Horne, whose team conducted both studies, says: “We redid the study among a different group of patients to see if we could replicate the results. We found essentially the same results – that people who fast routinely have a lower risk of coronary disease.” And do you remember the fat-mouse-versus-skinny-mouse paradigm presented by Panda earlier in this story? The bloodborne markers for heart disease – inflammation, high cholesterol – were much higher in the round-the-clock rodents than they were in the eight-hour wonder mice.

Beat cancer

Cancer happens when the body’s cells, which grow and divide constantly, begin to multiply out of control, impeding normal functions. Each moment of cell division, something that happens at least tens of thousands of times a day, is an opportunity for something to go haywire. But what if you could slow that cell growth? That’s one rev counter you don’t want to redline. Cancer strikes for many reasons, and a lot of them aren’t fully understood. But one contributing factor to our cancer risk is our diet, including the tremendous amount of food we’re regularly exposing our bodies to.

The process of cell reproduction in the body is sort of like a furnace – the more fuel you toss onto it, the hotter it burns. So when we eat morning, noon and night, we constantly feed that fire. But if we enjoy all our favourite foods in whatever quantities we want, but allow the fire to dampen for an extra few or more hours during the day, then we dramatically decrease our risk of cells multiplying out of control.

“The body is an incredibly efficient machine,” says Dr Marc Hellerstein, a professor of nutritional science and toxicology at the University of California at Berkeley. “Over millions of years our machine has been honed to expend less energy when the fuel supply drops off.” In a fasting state, cells, including cancer cells, multiply at a greatly reduced rate. “Periodic fasting can prevent cancer, we think, by slowing the rate at which all cells in the body divide,” says Hellerstein. “It turns the gear down – instead of liver cells, breast cells, prostate cells dividing every three days, they divide every six days. The cells don’t have such a chance of heading toward carcinogenesis.”

Easy as pie

One of the more surprising discoveries for Chant about Eat Stop Eat is how simple it’s been to do. Granted, during his first 24-hour fast, he thought about food “every two minutes”, he admits. But he soon made a couple of tweaks that cleared the way for effortless deprivation.

The first was to change his self-talk from negative statements (“I can’t eat till 7pm tomorrow”) to positive ones (“I will eat at 7pm tomorrow.”)

The second was to adjust the way he thought about hunger, waves of which still strike him during fasts, typically late morning and mid afternoon.
“You have to be clear what it is you’re experiencing when you think you’re hungry,” says Chant. “I’m not in pain. I’m not even uncomfortable. I just have an empty feeling in my gut – that’s all. And half an hour later, it’s gone.”

Teamed with weight training three times a week, says Chant, IF has delivered more fat loss than anything he’s tried before, including low-carb diets (which are quite effective, he says, much more so than limiting dietary fat) and throwing large sums of money at personal trainers.

From two fasts a week, he’s now doing just one as he focuses on adding lean muscle to his sinewy 70kg frame. He chooses his fasting day according to what’s in his diary. If he’s due to catch up with a mate for a meal or there’s a staff lunch scheduled, well, the fast can wait a day. “This doesn’t have to wreck your social life,” he says.

Generally, he’ll work out on empty before breaking his latest fast. Friends and colleagues tend to be incredulous about this. They assume he must feel weak and dizzy, even faint. But he’s not felt any of those things, he says. If anything, he finds it easier to concentrate in the fasted state.

“Look, this has worked for me,” says Chant. “For someone who’d never really changed his body, I’ve done it and I’ve done it in a short period of time. And I’ll continue to do it because it’s changed my life. When I had that gut, I never wore a T-shirt. I wouldn’t take my top off on the beach. Now I have a 30-inch waist and I do what I like.”

*Disclaimer: David Zinczenko is co-author of the 8-Hour Diet