Tag Archives: diet

BigBang, Idea Soup

Forget Broccoli. It’s All About the Blue Zones

You should know how to live to be 100 years old by now. Tip number one: inherit good genes. Tip number two: forget uploading your consciousness to an AI, for now. Tip number three: live and eat in a so-called Blue Zone. Tip number four: walk fast, eat slowly.

From the NYT:

Dan Buettner and I were off to a good start. He approved of coffee.

“It’s one of the biggest sources of antioxidants in the American diet,” he said with chipper confidence, folding up his black Brompton bike.

As we walked through Greenwich Village, looking for a decent shot of joe to fuel an afternoon of shopping and cooking and talking about the enigma of longevity, he pointed out that the men and women of Icaria, a Greek island in the middle of the Aegean Sea, regularly slurp down two or three muddy cups a day.

This came as delightful news to me. Icaria has a key role in Mr. Buettner’s latest book, “The Blue Zones Solution,” which takes a deep dive into five places around the world where people have a beguiling habit of forgetting to die. In Icaria they stand a decent chance of living to see 100. Without coffee, I don’t see much point in making it to 50.

The purpose of our rendezvous was to see whether the insights of a longevity specialist like Mr. Buettner could be applied to the life of a food-obsessed writer in New York, a man whose occupational hazards happen to include chicken wings, cheeseburgers, martinis and marathon tasting menus.

Covering the world of gastronomy and mixology during the era of David Chang (career-defining dish: those Momofuku pork-belly buns) and April Bloomfield (career-defining dish: the lamb burger at the Breslin Bar and Dining Room) does not exactly feel like an enterprise that’s adding extra years to my life — or to my liver.

And the recent deaths (even if accidental) of men in my exact demographic — the food writer Joshua Ozersky, the tech entrepreneur Dave Goldberg — had put me in a mortality-anxious frame of mind.

With my own half-century mark eerily visible on the horizon, could Mr. Buettner, who has spent the last 10 years unlocking the mysteries of longevity, offer me a midcourse correction?

To that end, he had decided to cook me something of a longevity feast. Visiting from his home in Minnesota and camped out at the townhouse of his friends Andrew Solomon and John Habich in the Village, this trim, tanned, 55-year-old guru of the golden years was geared up to show me that living a long time was not about subsisting on a thin gruel of, well, gruel.

After that blast of coffee, which I dutifully diluted with soy milk (as instructed) at O Cafe on Avenue of the Americas, Mr. Buettner and I set forth on our quest at the aptly named LifeThyme market, where signs in the window trumpeted the wonders of wheatgrass. He reassured me, again, by letting me know that penitent hedge clippings had no place in our Blue Zones repast.

“People think, ‘If I eat more of this, then it’s O.K. to eat more burgers or candy,’ ” he said. Instead, as he ambled through the market dropping herbs and vegetables into his basket, he insisted that our life-extending banquet would hinge on normal affordable items that almost anyone can pick up at the grocery store. He grabbed fennel and broccoli, celery and carrots, tofu and coconut milk, a bag of frozen berries and a can of chickpeas and a jar of local honey.

The five communities spotlighted in “The Blue Zones Solution” (published by National Geographic) depend on simple methods of cooking that have evolved over centuries, and Mr. Buettner has developed a matter-of-fact disregard for gastro-trends of all stripes. At LifeThyme, he passed by refrigerated shelves full of vogue-ish juices in hues of green, orange and purple. He shook his head and said, “Bad!”

“The glycemic index on that is as bad as Coke,” he went on, snatching a bottle of carrot juice to scan the label. “For eight ounces, there’s 14 grams of sugar. People get suckered into thinking, ‘Oh, I’m drinking this juice.’ Skip the juicing. Eat the fruit. Or eat the vegetable.” (How about a protein shake? “No,” he said.)

So far, I was feeling pretty good about my chances of making it to 100. I love coffee, I’m not much of a juicer and I’ve never had a protein shake in my life. Bingo. I figured that pretty soon Mr. Buettner would throw me a dietary curveball (I noticed with vague concern that he was not putting any meat or cheese into his basket), but by this point I was already thinking about how fun it would be to meet my great-grandchildren.

I felt even better when he and I started talking about strenuous exercise, which for me falls somewhere between “root canal” and “Justin Bieber concert” on the personal aversion scale.

I like to go for long walks, and … well, that’s about it.

“That’s when I knew you’d be O.K.,” Mr. Buettner told me.

It turns out that walking is a popular mode of transport in the Blue Zones, too — particularly on the sun-splattered slopes of Sardinia, Italy, where many of those who make it to 100 are shepherds who devote the bulk of each day to wandering the hills and treating themselves to sips of red wine.

“A glass of wine is better than a glass of water with a Mediterranean meal,” Mr. Buettner told me.

Red wine and long walks? If that’s all it takes, people, you’re looking at Methuselah.

O.K., yes, Mr. Buettner moves his muscles a lot more than I do. He likes to go everywhere on that fold-up bike, which he hauls along with him on trips, and sometimes he does yoga and goes in-line skating. But he generally believes that the high-impact exercise mania as practiced in the major cities of the United States winds up doing as much harm as good.

“You can’t be pounding your joints with marathons and pumping iron,” he said. “You’ll never see me doing CrossFit.”

For that evening’s meal, Mr. Buettner planned to cook dishes that would make reference to the quintet of places that he focuses on in “The Blue Zones Solution”: along with Icaria and Sardinia, they are Okinawa, Japan; the Nicoya Peninsula in Costa Rica; and Loma Linda, Calif., where Seventh-day Adventists have a tendency to outlive their fellow Americans, thanks to a mostly vegetarian diet that is heavy on nuts, beans, oatmeal, 100 percent whole-grain bread and avocados.

We walked from the market to the townhouse. And it was here, as Mr. Buettner laid out his cooking ingredients on a table in Mr. Solomon’s and Mr. Habich’s commodious, state-of-the-art kitchen, that I noticed the first real disconnect between the lives of the Blue Zones sages and the life of a food writer who has enjoyed many a lunch hour scarfing down charcuterie, tapas and pork-belly-topped ramen at the Gotham West Market food court.

Where was the butter? Hadn’t some nice scientists determined that butter’s not so lethal for us, after all? (“My view is that butter, lard and other animal fats are a bit like radiation: a dollop a couple of times a week probably isn’t going to hurt you, but we don’t know the safe level,” Mr. Buettner later wrote in an email. “At any rate, I can send along a paper that largely refutes the whole ‘Butter is Back’ craze.” No, thanks, I’m good.)

Where was the meat? Where was the cheese? (No cheese? And here I thought we’d be friends for another 50 years, Mr. Buettner.)

Read the entire article here.

Idea Soup

Sugar Is Bad For You, Really? Really!

 

sugar moleculesIn case you may not have heard, sugar is bad for you. In fact, an increasing number of food scientists will tell you that sugar is a poison, and that it’s time to fight the sugar oligarchs in much the same way that health advocates resolved to take on big tobacco many decades ago.

From the Guardian:

If you have any interest at all in diet, obesity, public health, diabetes, epidemiology, your own health or that of other people, you will probably be aware that sugar, not fat, is now considered the devil’s food. Dr Robert Lustig’s book, Fat Chance: The Hidden Truth About Sugar, Obesity and Disease, for all that it sounds like a Dan Brown novel, is the difference between vaguely knowing something is probably true, and being told it as a fact. Lustig has spent the past 16 years treating childhood obesity. His meta-analysis of the cutting-edge research on large-cohort studies of what sugar does to populations across the world, alongside his own clinical observations, has him credited with starting the war on sugar. When it reaches the enemy status of tobacco, it will be because of Lustig.

“Politicians have to come in and reset the playing field, as they have with any substance that is toxic and abused, ubiquitous and with negative consequence for society,” he says. “Alcohol, cigarettes, cocaine. We don’t have to ban any of them. We don’t have to ban sugar. But the food industry cannot be given carte blanche. They’re allowed to make money, but they’re not allowed to make money by making people sick.”

Lustig argues that sugar creates an appetite for itself by a determinable hormonal mechanism – a cycle, he says, that you could no more break with willpower than you could stop feeling thirsty through sheer strength of character. He argues that the hormone related to stress, cortisol, is partly to blame. “When cortisol floods the bloodstream, it raises blood pressure; increases the blood glucose level, which can precipitate diabetes. Human research shows that cortisol specifically increases caloric intake of ‘comfort foods’.” High cortisol levels during sleep, for instance, interfere with restfulness, and increase the hunger hormone ghrelin the next day. This differs from person to person, but I was jolted by recognition of the outrageous deliciousness of doughnuts when I haven’t slept well.

“The problem in obesity is not excess weight,” Lustig says, in the central London hotel that he has made his anti-metabolic illness HQ. “The problem with obesity is that the brain is not seeing the excess weight.” The brain can’t see it because appetite is determined by a binary system. You’re either in anorexigenesis – “I’m not hungry and I can burn energy” – or you’re in orexigenesis – “I’m hungry and I want to store energy.” The flip switch is your leptin level (the hormone that regulates your body fat) but too much insulin in your system blocks the leptin signal.

It helps here if you have ever been pregnant or remember much of puberty and that savage hunger; the way it can trick you out of your best intentions, the lure of ridiculous foods: six-month-old Christmas cake, sweets from a bin. If you’re leptin resistant – that is, if your insulin is too high as a result of your sugar intake – you’ll feel like that all the time.

Telling people to simply lose weight, he tells me, “is physiologically impossible and it’s clinically dangerous. It’s a goal that’s not achievable.” He explains further in the book: “Biochemistry drives behaviour. You see a patient who drinks 10 gallons of water a day and urinates 10 gallons of water a day. What is wrong with him? Could he have a behavioural disorder and be a psychogenic water drinker? Could be. Much more likely he has diabetes.” To extend that, you could tell people with diabetes not to drink water, and 3% of them might succeed – the outliers. But that wouldn’t help the other 97% just as losing the weight doesn’t, long-term, solve the metabolic syndrome – the addiction to sugar – of which obesity is symptomatic.

Many studies have suggested that diets tend to work for two months, some for as long as six. “That’s what the data show. And then everybody’s weight comes roaring back.” During his own time working night shifts, Lustig gained 3st, which he never lost and now uses exuberantly to make two points. The first is that weight is extremely hard to lose, and the second – more important, I think – is that he’s no diet and fitness guru himself. He doesn’t want everybody to be perfect: he’s just a guy who doesn’t want to surrender civilisation to diseases caused by industry. “I’m not a fitness guru,” he says, puckishly. “I’m 45lb overweight!”

“Sugar causes diseases: unrelated to their calories and unrelated to the attendant weight gain. It’s an independent primary-risk factor. Now, there will be food-industry people who deny it until the day they die, because their livelihood depends on it.” And here we have the reason why he sees this is a crusade and not a diet book, the reason that Lustig is in London and not Washington. This is an industry problem; the obesity epidemic began in 1980. Back then, nobody knew about leptin. And nobody knew about insulin resistance until 1984.

“What they knew was, when they took the fat out they had to put the sugar in, and when they did that, people bought more. And when they added more, people bought more, and so they kept on doing it. And that’s how we got up to current levels of consumption.” Approximately 80% of the 600,000 packaged foods you can buy in the US have added calorific sweeteners (this includes bread, burgers, things you wouldn’t add sugar to if you were making them from scratch). Daily fructose consumption has doubled in the past 30 years in the US, a pattern also observable (though not identical) here, in Canada, Malaysia, India, right across the developed and developing world. World sugar consumption has tripled in the past 50 years, while the population has only doubled; it makes sense of the obesity pandemic.

“It would have happened decades earlier; the reason it didn’t was that sugar wasn’t cheap. The thing that made it cheap was high-fructose corn syrup. They didn’t necessarily know the physiology of it, but they knew the economics of it.” Adding sugar to everyday food has become as much about the industry prolonging the shelf life as it has about palatability; if you’re shopping from corner shops, you’re likely to be eating unnecessary sugar in pretty well everything. It is difficult to remain healthy in these conditions. “You here in Britain are light years ahead of us in terms of understanding the problem. We don’t get it in the US, we have this libertarian streak. You don’t have that. You’re going to solve it first. So it’s in my best interests to help you, because that will help me solve it back there.”

The problem has mushroomed all over the world in 30 years and is driven by the profits of the food and diet industries combined. We’re not looking at a global pandemic of individual greed and fecklessness: it would be impossible for the citizens of the world to coordinate their human weaknesses with that level of accuracy. Once you stop seeing it as a problem of personal responsibility it’s easier to accept how profound and serious the war on sugar is. Life doesn’t have to become wholemeal and joyless, but traffic-light systems and five-a-day messaging are under-ambitious.

“The problem isn’t a knowledge deficit,” an obesity counsellor once told me. “There isn’t a fat person on Earth who doesn’t know vegetables are good for you.” Lustig agrees. “I, personally, don’t have a lot of hope that those things will turn things around. Education has not solved any substance of abuse. This is a substance of abuse. So you need two things, you need personal intervention and you need societal intervention. Rehab and laws, rehab and laws. Education would come in with rehab. But we need laws.”

Read the entire article here.

Image: Molecular diagrams of sucrose (left) and fructose (right). Courtesy of Wikipedia.

 

Environs

Living Long and Prospering on Ikaria

It’s safe to suggest that most of us above a certain age — let’s say 30 — wish to stay young. It is also safer to suggest, in the absence of a solution to this first wish, that many of us wish to age gracefully and happily. Yet for most of us, especially in the West, we age in a less dignified manner in combination with colorful medicines, lengthy tubes, and unpronounceable procedures. We are collectively living longer. But, the quality of those extra years leaves much to be desired.

In a quest to understand the process of aging more thoroughly researchers regularly descend on areas the world over that are known to have higher than average populations of healthy older people. These have become known as “Blue Zones”. One such place is a small, idyllic (there’s a clue right there) Greek island called Ikaria.

From the Guardian:

Gregoris Tsahas has smoked a packet of cigarettes every day for 70 years. High up in the hills of Ikaria, in his favourite cafe, he draws on what must be around his half-millionth fag. I tell him smoking is bad for the health and he gives me an indulgent smile, which suggests he’s heard the line before. He’s 100 years old and, aside from appendicitis, has never known a day of illness in his life.

Tsahas has short-cropped white hair, a robustly handsome face and a bone-crushing handshake. He says he drinks two glasses of red wine a day, but on closer interrogation he concedes that, like many other drinkers, he has underestimated his consumption by a couple of glasses.

The secret of a good marriage, he says, is never to return drunk to your wife. He’s been married for 60 years. “I’d like another wife,” he says. “Ideally one about 55.”

Tsahas is known at the cafe as a bit of a gossip and a joker. He goes there twice a day. It’s a 1km walk from his house over uneven, sloping terrain. That’s four hilly kilometres a day. Not many people half his age manage that far in Britain.

In Ikaria, a Greek island in the far east of the Mediterranean, about 30 miles from the Turkish coast, characters such as Gregoris Tsahas are not exceptional. With its beautiful coves, rocky cliffs, steep valleys and broken canopy of scrub and olive groves, Ikaria looks similar to any number of other Greek islands. But there is one vital difference: people here live much longer than the population on other islands and on the mainland. In fact, people here live on average 10 years longer than those in the rest of Europe and America – around one in three Ikarians lives into their 90s. Not only that, but they also have much lower rates of cancer and heart disease, suffer significantly less depression and dementia, maintain a sex life into old age and remain physically active deep into their 90s. What is the secret of Ikaria? What do its inhabitants know that the rest of us don’t?

The island is named after Icarus, the young man in Greek mythology who flew too close to the sun and plunged into the sea, according to legend, close to Ikaria. Thoughts of plunging into the sea are very much in my mind as the propeller plane from Athens comes in to land. There is a fierce wind blowing – the island is renowned for its wind – and the aircraft appears to stall as it turns to make its final descent, tipping this way and that until, at the last moment, the pilot takes off upwards and returns to Athens. Nor are there any ferries, owing to a strike. “They’re always on strike,” an Athenian back at the airport tells me.

Stranded in Athens for the night, I discover that a fellow thwarted passenger is Dan Buettner, author of a book called The Blue Zones, which details the five small areas in the world where the population outlive the American and western European average by around a decade: Okinawa in Japan, Sardinia, the Nicoya peninsula in Costa Rica, Loma Linda in California and Ikaria.

Tall and athletic, 52-year-old Buettner, who used to be a long-distance cyclist, looks a picture of well-preserved youth. He is a fellow with National Geographic magazine and became interested in longevity while researching Okinawa’s aged population. He tells me there are several other passengers on the plane who are interested in Ikaria’s exceptional demographics. “It would have been ironic, don’t you think,” he notes drily, “if a group of people looking for the secret of longevity crashed into the sea and died.”

Chatting to locals on the plane the following day, I learn that several have relations who are centenarians. One woman says her aunt is 111. The problem for demographers with such claims is that they are often very difficult to stand up. Going back to Methuselah, history is studded with exaggerations of age. In the last century, longevity became yet another battleground in the cold war. The Soviet authorities let it be known that people in the Caucasus were living deep into their hundreds. But subsequent studies have shown these claims lacked evidential foundation.

Since then, various societies and populations have reported advanced ageing, but few are able to supply convincing proof. “I don’t believe Korea or China,” Buettner says. “I don’t believe the Hunza Valley in Pakistan. None of those places has good birth certificates.”

However, Ikaria does. It has also been the subject of a number of scientific studies. Aside from the demographic surveys that Buettner helped organise, there was also the University of Athens’ Ikaria Study. One of its members, Dr Christina Chrysohoou, a cardiologist at the university’s medical school, found that the Ikarian diet featured a lot of beans and not much meat or refined sugar. The locals also feast on locally grown and wild greens, some of which contain 10 times more antioxidants than are found in red wine, as well as potatoes and goat’s milk.

Chrysohoou thinks the food is distinct from that eaten on other Greek islands with lower life expectancy. “Ikarians’ diet may have some differences from other islands’ diets,” she says. “The Ikarians drink a lot of herb tea and small quantities of coffee; daily calorie consumption is not high. Ikaria is still an isolated island, without tourists, which means that, especially in the villages in the north, where the highest longevity rates have been recorded, life is largely unaffected by the westernised way of living.”

But she also refers to research that suggests the Ikarian habit of taking afternoon naps may help extend life. One extensive study of Greek adults showed that regular napping reduced the risk of heart disease by almost 40%. What’s more, Chrysohoou’s preliminary studies revealed that 80% of Ikarian males between the ages of 65 and 100 were still having sex. And, of those, a quarter did so with “good duration” and “achievement”. “We found that most males between 65 and 88 reported sexual activity, but after the age of 90, very few continued to have sex.”

Read the entire article here.

Image: Agios Giorgis Beach, Ikaria. Courtesy of Island-Ikaria travel guide.

BigBang

Chocolate for the Soul and Mind (But Not Body)

Hot on the heels of the recent research finding that the Mediterranean diet improves heart health, come news that choc-a-holics the world over have been anxiously awaiting — chocolate improves brain function.

Researchers have found that chocolate rich in compounds known as flavanols can improve cognitive function. Now, before you rush out the door to visit the local grocery store to purchase a mountain of Mars bars (perhaps not coincidentally, Mars, Inc., partly funded the research study), Godiva pralines, Cadbury flakes or a slab of Dove, take note that all chocolate is not created equally. Flavanols tend to be found in highest concentrations in raw cocoa. In fact, during the process of making most chocolate, including the dark kind, most flavanols tend to be removed or destroyed. Perhaps the silver lining here is that to replicate the dose of flavanols found to have a positive effect on brain function, you would have to eat around 20 bars of chocolate per day for several months. This may be good news for your brain, but not your waistline!

[div class=attrib]From Scientific American:[end-div]

It’s news chocolate lovers have been craving: raw cocoa may be packed with brain-boosting compounds. Researchers at the University of L’Aquila in Italy, with scientists from Mars, Inc., and their colleagues published findings last September that suggest cognitive function in the elderly is improved by ingesting high levels of natural compounds found in cocoa called flavanols. The study included 90 individuals with mild cognitive impairment, a precursor to Alzheimer’s disease. Subjects who drank a cocoa beverage containing either moderate or high levels of flavanols daily for eight weeks demonstrated greater cognitive function than those who consumed low levels of flavanols on three separate tests that measured factors that included verbal fluency, visual searching and attention.

Exactly how cocoa causes these changes is still unknown, but emerging research points to one flavanol in particular: (-)-epicatechin, pronounced “minus epicatechin.” Its name signifies its structure, differentiating it from other catechins, organic compounds highly abundant in cocoa and present in apples, wine and tea. The graph below shows how (-)-epicatechin fits into the world of brain-altering food molecules. Other studies suggest that the compound supports increased circulation and the growth of blood vessels, which could explain improvements in cognition, because better blood flow would bring the brain more oxygen and improve its function.

Animal research has already demonstrated how pure (-)-epicatechin enhances memory. Findings published last October in the Journal of Experimental Biology note that snails can remember a trained task—such as holding their breath in deoxygenated water—for more than a day when given (-)-epicatechin but for less than three hours without the flavanol. Salk Institute neuroscientist Fred Gage and his colleagues found previously that (-)-epicatechin improves spatial memory and increases vasculature in mice. “It’s amazing that a single dietary change could have such profound effects on behavior,” Gage says. If further research confirms the compound’s cognitive effects, flavanol supplements—or raw cocoa beans—could be just what the doctor ordered.

So, Can We Binge on Chocolate Now?

Nope, sorry. A food’s origin, processing, storage and preparation can each alter its chemical composition. As a result, it is nearly impossible to predict which flavanols—and how many—remain in your bonbon or cup of tea. Tragically for chocoholics, most methods of processing cocoa remove many of the flavanols found in the raw plant. Even dark chocolate, touted as the “healthy” option, can be treated such that the cocoa darkens while flavanols are stripped.

Researchers are only beginning to establish standards for measuring flavanol content in chocolate. A typical one and a half ounce chocolate bar might contain about 50 milligrams of flavanols, which means you would need to consume 10 to 20 bars daily to approach the flavanol levels used in the University of L’Aquila study. At that point, the sugars and fats in these sweet confections would probably outweigh any possible brain benefits. Mars Botanical nutritionist and toxicologist Catherine Kwik-Uribe, an author on the University of L’Aquila study, says, “There’s now even more reasons to enjoy tea, apples and chocolate. But diversity and variety in your diet remain key.”

[div class=attrib]Read the entire article after the jump.[end-div]

[div class=attrib]Image courtesy of Google Search.[end-div]

BigBang

The Science (and Benefit) of Fasting

For thousands of years people have fasted to cleanse the body and the spirit. And, of course, many fast to lose (some) weight. Recently, a growing body of scientific research seems to suggest that fasting may slow the aging process.

[div class=attrib]From the New Scientist:[end-div]

THERE’S a fuzz in my brain and an ache in my gut. My legs are leaden and my eyesight is blurry. But I have only myself to blame. Besides, I have been assured that these symptoms will pass. Between 10 days and three weeks from now, my body will adjust to the new regime, which entails fasting for two days each week. In the meantime, I just need to keep my eyes on the prize. Forget breakfast and second breakfast, ignore the call of multiple afternoon snacks, because the pay offs of doing without could be enormous.

Fasting is most commonly associated with religious observation. It is the fourth of the Five Pillars of Islam. Buddhists consider it a means to practise self-control and advocate abstaining from food after the noon meal. For some Christians, temporary fasts are seen as a way of getting closer to God. But the benefits I am hoping for are more corporeal.

The idea that fasting might be good for your health has a long, if questionable, history. Back in 1908, “Dr” Linda Hazzard, an American with some training as a nurse, published a book called Fasting for the Cure of Disease, which claimed that minimal food was the route to recovery from a variety of illnesses including cancer. Hazzard was jailed after one of her patients died of starvation. But what if she was, at least partly, right?

A new surge of interest in fasting suggests that it might indeed help people with cancer. It could also reduce the risk of developing cancer, guard against diabetes and heart disease, help control asthma and even stave off Parkinson’s disease and dementia. Many of the scientists who study fasting practise what they research, and they tell me that at my age (39) it could be vital that I start now. “We know from animal models,” says Mark Mattson at the US National Institute on Aging, “that if we start an intermittent fasting diet at what would be the equivalent of middle age in people, we can delay the onset of Alzheimer’s and Parkinson’s.” Surely it’s worth a try?

Until recently, most studies linking diet with health and longevity focused on calorie restriction. They have had some impressive results, with the lifespan of various lab animals lengthened by up to 50 per cent after their daily calorie intake was cut in half. But these effects do not seem to extend to primates. A 23-year-long study of macaques found that although calorie restriction delayed the onset of age-related diseases, it had no impact on lifespan. So other factors such as genetics may be more important for human longevity too (Nature, vol 489, p 318).

That’s bad news for anyone who has gone hungry for decades in the hope of living longer, but the finding has not deterred fasting researchers. They point out that although fasting obviously involves cutting calories – at least on the fast days – it brings about biochemical and physiological changes that daily dieting does not. Besides, calorie restriction may leave people susceptible to infections and biological stress, whereas fasting, done properly, should not. Some even argue that we are evolutionarily adapted to going without food intermittently. “The evidence is pretty strong that our ancestors did not eat three meals a day plus snacks,” says Mattson. “Our genes are geared to being able to cope with periods of no food.”

What’s in a fast?

As I sit here, hungry, it certainly doesn’t feel like that. But researchers do agree that fasting will leave you feeling crummy in the short term because it takes time for your body to break psychological and biological habits. Less reassuring is their lack of agreement on what fasting entails. I have opted for the “5:2” diet, which allows me 600 calories in a single meal on each of two weekly “fast” days. The normal recommended intake is about 2000 calories for a woman and 2500 for a man, and I am allowed to eat whatever I want on the five non-fast days, underlining the fact that fasting is not necessarily about losing weight. A more draconian regimen has similar restricted-calorie “fasts” every other day. Then there’s total fasting, in which participants go without food for anything from one to five days – longer than about a week is considered potentially dangerous. Fasting might be a one-off, or repeated weekly or monthly.

Different regimens have different effects on the body. A fast is considered to start about 10 to 12 hours after a meal, when you have used up all the available glucose in your blood and start converting glycogen stored in liver and muscle cells into glucose to use for energy. If the fast continues, there is a gradual move towards breaking down stored body fat, and the liver produces “ketone bodies” – short molecules that are by-products of the breakdown of fatty acids. These can be used by the brain as fuel. This process is in full swing three to four days into a fast. Various hormones are also affected. For example, production of insulin-like growth factor 1 (IGF-1), drops early and reaches very low levels by day three or four. It is similar in structure to insulin, which also becomes scarcer with fasting, and high levels of both have been linked to cancer.

[div class=attrib]Read the entire article following the jump.[end-div]