The World's Most Effective Diet

by: Sandra Prior

Monday morning in town. Skies are bright, air is clear and as I stroll to work, I easily spy 40 000kJ. Office workers gobbling croissants, muffins and coffees. The deli at the corner does brisk business. Two giant cheeseburgers hover over me on a billboard. But none for me, thanks.

I haven't eaten since Saturday night. Thirty-six hours. I'm not hungry. A bit spaced out, maybe, but in a peaceful way. This is maybe my sixtieth weekly fast in a row. I do this, honestly, because I love food. It's my favorite comfort, my most exquisite treat. I've forgone clothes, electronics and a better car in order to budget more for beef ravioli, fresh mozzarella and my favorite Cabernet Sauvignon.

But a few years ago, something began to turn. Knowing the way food soothed me, I started slipping - a milkshake from the popular takeaway outlet near work, a convenient cashew chicken from the local Chinese place.

My eating became mechanical, joyless. This is an easy trap to fall into: from our hunter-gatherer ancestors, we retain a genetically encoded anxiety - however unconscious - that food can be scarce. So we're hard-wired to eat when we can, even though food is ubiquitous. It's also cheap and tasty. Primal fear plus abundant food equals an obesity epidemic. For me, my love of food evolved into an imperative to eat that cared little for the distinction between fast food and foie gras. Apostasy. I committed to a year of weekly fasting to see if I could restore the relish to my life.

There are, it turns out, many reasons to fast. I was only vaguely aware of the health benefits when I started, but studies suggest that regularly abstaining from food lowers your heart rate and blood pressure, staves off diabetes and protects your tissues from the ravages of free radicals.

Fasting poses a good kind of stress, much like exercise. Our cells respond by increasing their ability to cope with other, stronger stresses. In rodent studies, fasting also confers dramatic resistance to cancer, brain ageing, stroke and heart disease. Since I began this experiment, I've lost five kilograms (from 83 to 78) and shaved two points from my body-mass index (from 25.6 to 23.6). More important, I love food again.

Fasting does, in fact, improve your taste-bud sensitivity to sweet and salty flavors. And fasting forces me to make better choices when I do eat. On either side of a fasting day, I crave smaller, more vegetal meals. Come midweek, I want to celebrate. I go for dry-aged steak and stinky cheese with less guilt and more gusto. And more patience. In practice, an empty gut brings a sense of peace, as if I'm on holiday. This calm, along with the promise of health, has kept me fasting beyond the year I initially committed to.

In the last hour of my fast this Monday morning, I fed my dogs, then myself. Nothing tastes better than a sip of orange juice poured into that calm. And strawberries. Yum. Three of them and I'm full.

Nearly a week later, I'm ready again. Eager for it, really: my gustatory reset button. I typically fast from Saturday night until breakfast on Monday, drinking only water, only when I'm thirsty, and beginning and ending the fast with light meals. Tonight it's kale, rice, chicken and melon - a high-fibre selection. Last meals can lead to constipation if they don't contain enough fibre to push through your system. I read this in a book and confirmed its veracity by ignoring it.

That book, called Celebration of Discipline, by Richard Foster, is a guide to spiritual Christian practices. Tonight, I read the fasting chapter again. Foster's tone works for me. There's no histrionics - going without food is no big deal. This was critical for my first few fasts. When my inner food-child threw a tantrum, I responded with nonchalance, and it worked.

I didn't look beyond Foster for months, and I'm glad. Most fasting information out there is nonsense. Charlatans promote it as part of their weight-loss scams. Most doctors are equally as ignorant. When I asked one about it, he mumbled something about electrolytes and cardiac arrhythmias before surrendering: ‘They don't teach fasting in medical school.’

They ought to, if only out of respect for the billions of people who fast for religious reasons, from Yom Kippur to various Christian and Hindu holidays to Ramadan. And there is strong, if scattered, scientific literature that includes empirical evidence from doctors with fasting experience; a smattering of more-controlled experiments in humans; overwhelming evidence from animal experiments; and a sort of amicus brief from a better-studied field called calorie restriction. In calorie restriction, participants eat only 60 percent to 70 percent of their weight-maintenance intake. This consistently decreases the biological rate of ageing and increases lifespan.

One empiricist is Dr Joel Fuhrman, a family doctor and author of Fasting and Eating for Health. He has put thousands of patients on multiday fasts and followed their vital signs and blood work closely. For a healthy person, medical supervision is not needed for a five-day fast. He's never seen electrolyte depletion or potassium loss, which can cause cardiac arrhythmias, prior to the tenth day of a fast.

Fuhrman instructs patients with inflammatory problems like lupus and arthritis to consider episodic fasting. I have Crohn's, an inflammatory bowel disease. I've had far fewer flare-ups in the past 14 months. Rodent studies show this anti-inflammatory benefit, as does at least one human study. Dr James Johnson, author of The Alternate-Day Diet, put nine overweight asthma patients on a near-fasting regime every other day for eight weeks. On average, those patients lost eight percent of their weight, lowered their cholesterol by 20 points and improved their airflow by 15 percent due to less airway inflammation. There's nothing out there that would work as well as that, other than systemic steroids.

Other studies piece together what happens to hunger strikers and starvation victims. The bottom line: our bodies are built to go long stretches without food. When you eat, your liver and muscles store up energy in the form of glycogen. When you fast, your body feeds off that glycogen for several days and then starts burning your fat stores. Once those are depleted, starvation starts: the body breaks down muscle first and then organs, which leads to death after eight to 10 weeks. This timeline assumes access to water. Dehydration can kill in days.

For me, fasting is vaguely spiritual, a time for reflection. I close my eyes and munch on my last bit of melon. I picture a hunter-gatherer ancestor. He hasn't killed game in days, but that's okay. He has bodily wisdom to last many weeks. That's an awesome capability. My 36 hours is a mere gesture.

Any other day I develop a headache if I skip coffee, but not on fasting days. I have no idea why. I often play squash with my friend, and I exhibit fierce energy on the court. My body feels springy on fasting mornings, and my mind is as clear as water. I occasionally choose different days to fast, to work it comfortably around dinner parties, travel and whatnot, and by now I've done it on every day of the week. I've gone to work, driven long distances, taken hikes, had sex and lifted weights while fasting. Admittedly, I'm flying in the face of alternative medicine, which considers fasting a detoxifying process best done by easing into it. Don't send so much blood to your muscles, the theory goes - send it all to your liver. Without digestion of food to deal with, the liver can scrub the blood, ridding it of pesticides, food additives and other toxins. These exit through your pores, sinuses, colon and urine. Some people apparently suffer from acne, rashes and headaches while fasting. I don't. But my tongue coats over with a white film, and my breath stinks. These are classic signs of detoxification.

Fasting increases production of several molecules, including brain-derived neurotrophic factor, which protect the neurons from all sorts of disease down the line. Fasting rats show better memory, cognition, motor function and neurogenesis (production of new nerve cells from stem cells). He's shown that fasting mice bounce back from heart attacks and strokes better than everyday eaters.

If just a fraction of the fasting benefits seen in rodents were conferred by a pill, drug companies would be racing to prove them in humans. The human studies so far have involved too few participants to yield sweeping claims. Having said that, in the studies that have been done, there are no documented downsides to fasting. None. But that doesn't mean they're not there. One problem that crops up in the similar world of calorie restriction: fertility takes a dive. I know my sperm is okay. A Crohn's medication had tanked my sperm count, but I've been off the drug for three months - fasting weekly the whole time - and recent testing shows my swimmers are once again rigorous and plentiful.

I admit it: on Sunday afternoon, I usually get hungry. The primitive drive to eat is strong. I've cut a few fasts down to 24 hours. Twice I gave up fasting for good, but within 10 days I noticed my food sense regressing. I started eating crap again, and my body started creeping back up to its prefasting weight. I returned to the practice. I'm hooked, it seems, despite myself.

None of this helps when I'm hungry on a fasting day. I don't know if, like the rats, I'm getting any smarter over time, but I do know that when I'm in the thick of a 36-hour fast, intellectual activity is best avoided. Rearranging the furniture is great. The best afternoon pastime, honestly, is to nap. Naps on fasting days are glorious. I instantly go deep and drool on my pillow, and I wake up in the best part of my fast, my peaceful zone.

By five in the afternoon, my hunger is gone and I am infused in this calm that I can't describe, except to say that when I'm in it, I'd rather not talk to you. For once in my week, I don't give a crap about email or my to-do list. Time dilates in my perception. It also frees up for real, regifting me the two hours I'd normally spend preparing and eating food. I also like grocery shopping on fasting days.

It's a happy preview of what I will eat in the days ahead. What I will savor with the gusto and guiltlessness of a man who's earned it: fresh asparagus with organic blue cheese, roasted leek and Rosa tomata tart, lamb tagine with medjool dates, home-made chocolate-cake with cracked hazelnuts...

It's enough to make me not want to eat. Not yet.