Horizon Eat, Fast and Live Longer

"Michael Mosley has set himself a truly ambitious goal: he wants to live longer, stay younger and lose weight in the bargain. And he wants to make as few changes to his life as possible along the way. He discovers the powerful new science behind the ancient idea of fasting, and he thinks he's found a way of doing it that still allows him to enjoy his food. Michael tests out the science of fasting on himself - with life-changing results."

Eat, Fast and Live Longer - Horizon from Steve Hartman on Vimeo.

The Anti-Aging revolution

From CNNmoney
By David Stipp

In early 1934, Depression-weary Americans were beginning to see tendrils of hope poking out of the bleak landscape. President Franklin D. Roosevelt's New Deal was bringing the economy back from the dead. Galvanized by the sight of elderly women scrounging for food from garbage, California physician Francis Townsend had launched a crusade for government-funded pensions that would soon spur the creation of Social Security. Things were even looking up for the long-suffering Washington Senators, who had made it to the World Series the previous fall.

But one of the new year's most promising developments passed almost unnoticed. According to a brief article in the Jan. 13 Science News Letter, Cornell University researcher Clive McCay was nearing the end of a four-year study that showed that rats' life spans were greatly extended when they were put on near-starvation diets.

To many of his scientific peers, McCay's data made no sense at all. A glorious new chapter in nutrition science had been opened not long before by the discovery of dietary deficiencies behind scourges such as rickets, pellagra, and beriberi. In the wake of such progress, it seemed almost subversive to suggest that a bunch of rodent Oliver Twists, raised on such short rations that their growth was stunted, could live radically longer than well-fed ones. McCay sheepishly acknowledged in his initial report that his results seemed "little short of heresy."

Over the next several decades, his discovery was all but forgotten outside of the back halls of science -- a laboratory curiosity that didn't actually spark much curiosity. Most scientists were reluctant to risk wasting time probing an anomaly that seemed as baffling as aging itself.

Calorie restriction (CR), as it's now called, eventually was shown to extend many species' life spans by a third or more. Now that anti-aging research is hot, it seems bizarre that CR spent decades on science's back shelf. Simply put, McCay showed that the rate of aging is incredibly plastic, and that it's supremely simple to brake it in animals whose inner workings aren't all that different from ours. No biomedical discovery of the past century was more astonishing or significant.

So here's a prediction: McCay will someday be recognized as one of the last century's most important discoverers. He wasn't a genius with a capital G. But his skinny rats had made history with a capital H.

The idea of mimicking CR with drugs -- and without the hunger pangs that discourage most people from trying it -- finally got traction in the late 1990s when scientists began getting hints on the kinds of compounds that might work. (It had always been clear that such medicines were needed to make CR's broad health- and longevity-enhancing effects available to the masses, but before then researchers knew too little to get started.) Around 2000 several biotech startups were formed to pursue CR mimetics, including LifeGen Technologies of Madison, BioMarker Pharmaceuticals of San Jose, and GeroScience of Pylesville, Md. This first wave of CR-mimetic companies have been low-profile affairs compared with Sirtris Pharmaceuticals, the Cambridge, Mass., biotech juggernaut formed a few years later to develop drugs based on resveratrol, the famous red-wine compound shown to induce CR-like effects in animals. (Sirtris was acquired by GlaxoSmithKline in 2008.) They haven't been idle, though. GeroScience has worked with Procter & Gamble's (PG, Fortune 500) pet food unit, for example, on CR mimetics for pets, including a sugar in avocados called mannoheptulose. I wouldn't be surprised to see Fido and Muffy launch the era of effective anti-aging medicines.

The startups also deserve credit for beginning to transform the anti-aging quest from a guessing game into a fairly routine exercise in drug development. Before the pursuit of CR mimetics took off, most anti-aging investigators were like blind magicians trying to pull rabbits from a barrel of snakes. Not surprisingly, even the serious scientists among them often wound up covered in snake oil, promoting "breakthroughs" such as monkey-testicle implants and radium-laced elixirs.

CR-mimetic developers don't have to solve the monster problem of how aging happens in order to devise interventions that oppose it. Evolution has solved the problem for them. It did so while fashioning CR's machinery, which is poised to carry out all the intricate metabolic adjustments necessary to brake aging when activated by a true CR mimetic. Such drugs will be designed to switch on an ancient, enormously complex mechanism embedded in our genomes to postpone, and possibly attenuate, a myriad of ills brought on by aging: dementia, heart disease, cancer, as well as wrinkles, arthritis, age-related loss of muscle and bone, and the onset of senior moments. In effect, they'll represent the biggest free lunch in medical history. And given that compounds capable of emulating key effects of CR in rodents have already come to light, it's arguable that the Great Free Lunch's appetizers are now on the table.

0:00 /3:16Growing brand-new organs on-demand

Just a few weeks before his death in 1996 at age 100, George Burns was still enjoying life, cracking wise at a Christmas party thrown by Frank Sinatra. France's Jeanne Calment, who holds the record for longevity (she died in 1997 at 122), was similarly droll and unsinkable. When a reporter at an annual party in her honor departed with the words "Until next year, perhaps?" she shot back, "I don't see why not! You don't look so bad to me."

Very old people with such élan are obviously rare. But I suspect that many who retain mental clarity in late life make their way toward something like Burns' and Calment's radiant rapprochement with old age. Surveys show that self-reported happiness among older people in reasonably good health is generally higher than among younger groups. I don't want to sugarcoat old age -- it isn't for sissies, as they say. But I'd love to see more well-tempered sages like Burns in the world. Call it the George Burns scenario.

Some critics argue that developing anti-aging drugs is likely to engender a disastrous surfeit of needy oldsters gripped by greed and ennui. Leon Kass, a University of Chicago professor who chaired the President's Council on Bioethics under George W. Bush, has asserted, for instance, that "the desire to prolong youthfulness [is] an expression of a childish and narcissistic wish incompatible with devotion to posterity." Some naysayers add that "greedy geezers" will rack up ruinous Medicare and Social Security bills. Worse, they argue, the drugs may simply drag out late-life morbidity, recreating en masse something like the Greek myth of Tithonus, who was granted eternal life but not everlasting youth and wound up miserably withered forever.

I regard such visions as ill-founded. For one thing, there's evidence that CR mimetics would buy us quality time, not prolong misery. A study of CR's effects in rhesus monkeys has shown that it reduces age-related diseases by about a third in the primates during their later lives -- the calorie-restricted monkeys have greater lean muscle mass, significantly less age-related brain atrophy, half as much cancer, and half as much cardiovascular disease as do peers on normal diets. The world's longest-lived human population, natives of Japan's Okinawa prefecture, whose scant traditional diets are regarded as tantamount to mild CR, have 80% less breast and prostate cancer at advanced ages than North Americans do, suffer about 40% fewer hip fractures, and experience half the rate of dementia between 85 and 90.

It's possible that anti-aging drugs would compress late-life misery, letting us reach a ripe old age in good shape before a speedy demise. That could have huge economic and social payoffs -- much greater, for instance, than a miracle cure for all cancers.

Even if the medicines only postponed aging's deterioration, boosting life expectancy by, say, a decade, the benefits would be monumental. As Richard Miller, a University of Michigan gerontologist, says, "When you ask people, 'Would you like to live to 100?' they picture what today's elderly, infirm person looks and feels like. But the proper question is a different one: 'Would you like to add another 10 or 20 years to the middle of your life, so you reach 80 or 90 in the same condition that people generally are today at around 60 or 70?' "

A drug that increases healthy life-years would deliver large benefits across many sectors of the economy. Healthier, longer-living people can stay in the workforce longer, preserving skilled human capital that might otherwise be lost. Healthier workers are physically and mentally more robust, making them more productive. They're motivated to invest more in developing their skills, because they expect to reap the benefits of such investments for longer periods. They save more for retirement, boosting capital formation that fuels economic growth. They pose lighter burdens on federal entitlement programs and contribute more in federal and state tax revenue. Such factors probably explain why per-capita incomes of nations around the world have long risen in tandem with their populations' life expectancies.

Anti-aging drugs may well have downsides too. For instance, nest eggs that once seemed adequate may prove too small in an era of extended life spans. But the drugs should also help with that problem by keeping us vibrant enough to work after 62, the average age at which U.S. workers have retired in recent years. Of course, it remains to be seen whether the economy will support demand for older workers' services. Still, surveys show many baby boomers expect to work at least part-time in retirement for both fiscal and personal-fulfillment reasons -- they apparently agree with a piece of wisdom George Burns expressed late in life: "As long as you're working, you stay young."

Where does the anti-aging quest stand? As always with cutting-edge science, the quest has had ups and downs. In 2008, Harvard's David Sinclair and colleagues reported that resveratrol failed to extend the life spans of mice on normal diets, suggesting that it is at best a partial CR mimetic -- the group had earlier made a splash by showing that the compound induces CR-like effects in mice on high-fat diets. But last year a major turning point was reached: Researchers showed for the first time that a drug could convincingly extend life span in mammals.

The drug was rapamycin, a medicine long prescribed to help prevent rejection of transplanted organs. In parallel mouse experiments in three different labs, scientists funded by the National Institute on Aging found that rapamycin dramatically boosted longevity in mice on normal diets in a way reminiscent of CR's effects. Stunningly, the study showed that when rodents were first put on the drug at 20 months of age, roughly equivalent to 60 years in humans, the life expectancies of males were boosted by 28%, and that of females by 38%. Even CR itself hasn't been shown to exert such large effects on animals so close to the end of their lives. Former perma-bears about the anti-aging quest are now sounding upbeat.

Unfortunately, the drug industry has shown little interest in trying to translate such breakthroughs into anti-aging medicines. Both drug regulators and the medical establishment still essentially view aging as totally mysterious, inexorable, and intractable -- they wouldn't dream of adding it to the official list of drug indications. Thus, drug companies have no way to develop anti-aging compounds as high-margin prescription drugs. And that means that spending many hundreds of millions of dollars on clinical trials of the drugs' efficacy just doesn't compute. (The relatively small proceeds from marketing them as low-margin dietary supplements can't justify such costly, high-risk trials either.)

Besides, vetting the drugs would require first developing reliable biomarkers of aging, telltale signs of normal bodily decline over time that could be used to register how fast people are going downhill. Such biomarkers would enable the vetting of CR mimetics' efficacy in trials that last only a few years, rather than the impossibly long time it would take to assess their longevity-boosting effects in humans.

In short, the hugely promising anti-aging quest is now stuck between the R and the D stages, and I fear it will stay there until the federal government greatly steps up funding in the area. I, for one, don't plan to take purported CR mimetics until there's some reasonably rigorous clinical trial data showing that they're safe and effective. And until such data are available, the anti-aging revolution is likely to remain little more than the enthusiastic pursuit of placebo effects by wishful thinkers.

All this is terribly ironic. In effect, it means that authorities charged with promoting public health are fatalistically standing and watching the "silver tsunami" of population aging -- with its huge economic and human costs -- bearing down on us as if there were no way to shelter ourselves from its full force. Meanwhile, the authorities are perfectly willing to devote many billions of dollars annually to the pursuit of ever costlier palliatives for diseases of aging, which are typically applied when it's too late to do much good -- the federal government now annually spends less than 0.04% as much on research about the biology of aging as it does on Medicare.

So here's the moral of the story: The George Burns scenario is within our grasp if we collectively recognize what has happened in aging science and seize the day. And while anti-aging drugs may not enable all of us to live as long as Burns, they promise to let many of us age as gracefully as he did and thus aspire to our own version of his timelessness. As Burns once quipped, "You can't help getting older, but you don't have to get old." Words to remember from a wise guy to the end.

from fitnessspotlight.com: Benefits of Intermittent fasting

A good article on living the ADF life from fitnessspotlight.com
http://www.fitnessspotlight.com/2010/01/13/benefits-intermittent-fasting/

some highlights:
benefits of IF (ADF):

• Reduced blood glucose and insulin levels (markers of improved health)
• Increased fatty acid oxidation
• Maintenance of lean mass (muscle)
• Reduced inflammation
• Reduced oxidative damage
• Increased cellular stress resistance (esp of heart and brain)
• Decreased risks associated with degenerative diseases of aging (cancers, heart diseases, diabetes, Alzheimers)

Life extension by calorie restriction in humans

Everitt AV, Le Couteur DG (2007) Life extension by calorie restriction in humans Ann N Y Acad Sci. 1114:428-33

Abstract
Long-term reduction in energy intake in the diet (calorie restriction [CR]) extends the life of the laboratory rat by about 25%. However, in humans there are no life-long studies of CR, but only short-term trials which indicate that 20% CR acting over periods of 2-6 years is associated with reduced body weight, blood pressure, blood cholesterol, and blood glucose--risk factors for the major killer diseases of cardiovascular disease and diabetes. In addition, recent research has shown that CR for 6 months is able to improve biomarkers for longevity (deep body temperature and plasma insulin) and thus should increase life expectancy. The magnitude of the life-extension effect of CR in humans can only be estimated. The Okinawans, the longest-lived people on earth, consume 40% fewer calories than the Americans and live only 4 years longer. Similarly, women in United States consume 25% fewer calories than men and live 5 years longer. From the survival studies of overweight and obese people, it is estimated that long-term CR to prevent excessive weight gain could add only 3-13 years to life expectancy. Thus the effects of CR on human life extension are probably much smaller than those achieved by medical and public health interventions, which have extended life by about 30 years in developed countries in the 20th century, by greatly reducing deaths from infections, accidents, and cardiovascular disease

Reuters Health:Fasting Every Other Day Cuts Weight, Ups Crankiness

originally published February 1st, 2005 via womenfitness.net
http://www.womenfitness.net/news/wt_managment/fasting_every_other_day.htm
Fasting Every Other Day Cuts Weight, Ups Crankiness

NEW YORK (Reuters Health) - Shunning food every other day may be a feasible way to slash calories -- if you and those around you don't mind the crankiness that comes with it, according to researchers.

Their study of 16 nonobese men and women looked at the effects of alternate-day fasting, an eating plan that interspersed fasting days with "feasting" days that allowed participants to eat as much as they wanted.

The researchers were interested in whether food deprivation every second day would be easier on people than counting calories on a daily basis, lead author Dr. Eric Ravussin told Reuters Health.

They found that the diet plan was indeed "feasible," at least for the duration of the 3-week study. Overall, the men and women lost an average of 5 pounds, while shedding some body fat.

On the other hand, Ravussin said, "most people were not happy" -- a major problem being the crankiness that erupted on the fasting days and did not abate over the 3 weeks.

Ravussin and his colleagues at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, report the findings in the American Journal of Clinical Nutrition.

Uncovering the most tolerable ways for people to cut calories is not just a matter of trimming waistlines. A number of studies, Ravussin explained, have now shown that calorie restriction can extend the lives of everything from yeast and worms to rodents and, possibly, monkeys.

There are a number of theories on why limiting food might make for a longer, healthier life. One idea, Ravussin noted, is that slowing the rate of metabolism reduces the generation of oxygen free radicals, potentially cell-damaging molecules that are a normal byproduct of the metabolic process.

No one knows if calorie counting can extend human life as it does for some animals. Ravussin and his colleagues are currently conducting a trial, sponsored by the National Institutes of Health, which is examining how long-term dietary restriction affects people's health and longevity.

Studying dietary restriction in people is, of course, far more complicated than studying it in lab rats. The ongoing trial is investigating how calorie cutting affects "biomarkers of longevity" in people, such as levels of blood sugar and insulin, a hormone key in regulating blood sugar.

The trial is testing several methods of dietary restriction -- from pure calorie cutting to burning extra calories through exercise -- to see which are most viable.

In the current study, Ravussin's team evaluated the effects of alternate-day fasting, an approach not included in that trial. They wanted to see if the eating plan was feasible and whether it influenced biomarkers of longevity, as well as participants' weight and metabolism.

As mentioned, every other day for 3 weeks the men and women subsisted on calorie-free beverages and sugarless gum. On the days in between, they ate whatever they wanted.

According to Ravussin, participants were not able to "make up" for what they didn't eat on fasting days, and consequently, they generally lost a few pounds and some fat mass. In addition, their insulin levels declined by an average of about 57 percent.

However, the researchers also found that many participants said they were irritable on food-free days, and they did not appear to get used to having an empty stomach every other day.

Calorie restriction, Ravussin noted, is the only behavior that has so far been shown to prolong life. "There is a ton of data suggesting that this is the only way to the 'fountain of youth', if you want," he said. If the current findings are any indication, the researcher added, alternate-day fasting may not be the easiest path to that fountain.

SOURCE: American Journal of Clinical Nutrition, January 2005.

Musing Forces blog

Musing Forces blog is a first person account of one woman's alternate day fasting experiences. Great for people just starting off with ADF and wanting to know what to expect.
There are also great alternate day fasting links and resources on this blog.
http://musingforces.blogspot.com/

Alternate-day fasting and chronic disease prevention: a review of human and animal trials

Varady KA and Hellerstein MK (2007) Alternate-day fasting and chronic disease prevention: a review of human and animal trials. American Journal of Clinical Nutrition, Vol. 86, No. 1, 7-13, July 2007
http://www.ajcn.org/cgi/content/full/86/1/7

Abstract
Calorie restriction (CR) and alternate-day fasting (ADF) represent 2 different forms of dietary restriction. Although the effects of CR on chronic disease prevention were reviewed previously, the effects of ADF on chronic disease risk have yet to be summarized. Accordingly, we review here animal and human evidence concerning ADF and the risk of certain chronic diseases, such as type 2 diabetes, cardiovascular disease, and cancer. We also compare the magnitude of risk reduction resulting from ADF with that resulting from CR. In terms of diabetes risk, animal studies of ADF find lower diabetes incidence and lower fasting glucose and insulin concentrations, effects that are comparable to those of CR. Human trials to date have reported greater insulin-mediated glucose uptake but no effect on fasting glucose or insulin concentrations. In terms of cardiovascular disease risk, animal ADF data show lower total cholesterol and triacylglycerol concentrations, a lower heart rate, improved cardiac response to myocardial infarction, and lower blood pressure. The limited human evidence suggests higher HDL-cholesterol concentrations and lower triacylglycerol concentrations but no effect on blood pressure. In terms of cancer risk, there is no human evidence to date, yet animal studies found decreases in lymphoma incidence, longer survival after tumor inoculation, and lower rates of proliferation of several cell types. The findings in animals suggest that ADF may effectively modulate several risk factors, thereby preventing chronic disease, and that ADF may modulate disease risk to an extent similar to that of CR. More research is required to establish definitively the consequences of ADF.

From "The Independant": Feast & Famine: The Alternate Day Diet

Here is an article from the Indpendant I found wholly unconvincing. The nutritionists interviewed for this article warn against "unhealthy" and "unbalanced" eating habits and yet there is no data to support any of their claims. On the other hand, studies on the health and weight loss benefits of ADF do exist. The journalist's own personal account of her time on ADF (eat anything you want on one day and limited calories on the next) is only one of several ADF variants and i think few people actually following ADF, binge as she did on their eating days. Nevertheless she still lost 2 lbs which is a pretty incredible result especially for someone who didn't consider herself overweight to start with!

originally published Tuesday, 15 April 2008 in the Independant
http://www.independent.co.uk/life-style/health-and-families/healthy-living/feast--famine-the-alternate-day-diet-808940.html

Feast & Famine: The Alternate Day Diet
This promises fantastic weight-loss results - but to many nutritionists, it's heresy. Rachel Shields puts it to the test

It wasn't that long ago that we braved bad breath and high blood pressure on the Atkins, ignoring health warnings - and common sense - in our desperation to shed pounds. Recently, however, it has looked like the days of dangerous fad diets were over, replaced by a healthier, more sustainable attitude to weight loss. Sadly the growing buzz around a new eating plan suggests otherwise.

Dubbed "part-time anorexia" for the drastic eating pattern of bingeing and starving that it recommends, the Alternate Day Diet is the brainchild of plastic surgeon James B Johnson. Criticised by health professionals as physically and mentally damaging, the diet encourages followers to eat "whatever they want" every other day, but virtually nothing the next.

The idea of a diet in which absolutely no food is off limits is understandably seductive, particularly for those long-term dieters that have spent years ignoring the bread basket and turning down pudding. The gruelling diet days - also known as "down days" - are less appealing. On these days, followers must limit themselves to a meagre 300 to 500 calories. Given that the average woman needs 2,000 calories a day, and the average man 2,500, this seems woefully inadequate.

During the first few weeks of the diet, Dr Johnson advises dieters to consume their down-day calories in the form of protein shakes, to be sipped throughout the day.

Anna Denney, a nutrition scientist at the British Nutrition Foundation, says: "You will definitely feel the physical effects if you only eat 300 calories in a day - you'll probably feel hungry, sick and dizzy. Psychologically it is going to be challenging too - one day you are telling people to have no self-control, the next they have to have a will of iron."

So, imagine stuffing yourself with biscuits, chips, steak, wine, chocolate... every forbidden food, and then "balancing" it out by fasting the next day. If you think that this sounds more like an eating disorder than a diet plan, you are not alone. Dr Johnson's diet has already captured the attention of pro-anorexia websites and - even more worryingly - teen internet message boards, on which girls as young as 12 swap health and beauty tips.

There are notable parallels between the Alternate Day Diet and bulimia - a condition that has affected many influential celebrities, including Britney Spears and Geri Halliwell, in which sufferers deprive themselves of food, and then overeat to compensate - and experts have expressed concerns that the diet may encourage unhealthy eating patterns.

"A disordered eating pattern such as this is obviously not to be recommended," says Mary George of the eating disorder charity Beat. "Depriving the body of regular nutrients in this way over a period of time could lead to long-term harm and possibly take someone down the path to a full-blown eating disorder."

Instances of eating disorders in the UK have more than doubled since the 1960s, with binge-and-purge eating patterns becoming more and more common. An estimated 3 per cent of females in Britain between the ages of 10 and 20 suffer from problemsrelated to a binge-and-purge diet.

While it must be remembered that eating disorders are a mental illness, not just "a diet gone wrong", health professionals believe that countless people are engaged in a less severe, but still extremely damaging, cycle of "binge and starve" eating. This cycle often begins when an individual attempts to restrict their food intake order to lose weight, but then "breaks" their diet and overeats due to feelings of deprivation and hunger.

Dr Graham McGregor, professor of cardiovascular medicine at St George's Hospital, London, says: "We did studies on medical students in which we saw that people who fasted would get so hungry that they'd then binge on the worst possible foods. It is a see-saw effect. You also get lots of salt one day and very little the next, which has a dramatic effect on the body. It is a totally unphysiological thing to do."

Despite the stresses that such extreme eating patterns place on the human body - overloading the digestive system, raising blood pressure and causing dehydration - Dr McGregor believes that this is now extremely widespread.

"Most women starve and binge to an extent," he says. "They want to lose weight, so they eat very little, then they get really hungry and when their boyfriend takes them out to dinner, they eat a huge meal."

While Dr Johnson, who is based in New Orleans, admits that extreme diets can trigger or exacerbate eating disorders, he denies that his new diet encourages this sort of unhealthy behaviour. He insists that the small amounts of food allowed on down days are enough to prevent dieters experiencing the extreme hunger that could lead to gorging on up days.

"I haven't seen anybody on this diet who goes to extremes and binges or starves," says Dr Johnson. "I don't recommend going without food completely, because if you starve all day then that can trigger a loss of control and you'll be non-stop eating." He believes that the diet actually regulates the appetite, meaning that if people have eaten lots one day, they will be less hungry the next.

Denney disagrees. "Eating lots one day and little the next doesn't teach people the importance of balance in their diet," she argues. "Young people in particular need to learn to regulate what they eat, and a day of gluttony followed by a day of starvation won't help them to do this."

Dr Johnson's book claims that the roller-coaster calorie consumption of alternate day eating is not only easy to follow, but also triggers physical effects that help followers to lose weight. While most low-calorie diets slow down the metabolism, reducing the rate at which the body burns calories and thus hindering weight loss, Dr Johnson insists that his diet works to speed up the metabolism, tricking the body into burning up more calories than before.

"There was a study at the Pennington Biomedical Research Institute where volunteers ate nothing at all every other day for three weeks. They lost 2 per cent of their body weight over that time, but their resting energy expenditure didn't change. The alternating days system prevented the metabolic rate from dropping."

The idea for the diet came about after Dr Johnson, who had struggled with his own weight, spotted a scientific study in the American Journal of Clinical Nutrition which suggested that mice that were fed only every other day experienced significant weight loss and other health benefits.

"When I read it, it struck me like a thunderbolt," says Dr Johnson. "It just made sense. Personally, I knew that I couldn't do 'not eating anything' on alternate days, but I could cope with consuming about 20 per cent of my normal daily intake."

In the clinical trials Dr Johnson conducted in 2004, he said that volunteers lost on average 8 per cent of their body weight over an 8-week period, and experienced other health benefits.

"I was sure that the diet had benefits other than losing weight, so I picked some asthma sufferers to take part in the trial," adds Dr Johnson. "They showed dramatic improvements in their peak flow (how fast you can blow air in and out of your lungs). There is a clear biological hypothesis for this - the very low calorie intake on the down day triggers an anti-inflammatory gene, which improves the asthma."

Johnson believes that his diet can also help to lower blood pressure and improve conditions such as arthritis, as well as reducing levels of potentially harmful free radicals in the bloodstream - claims that have already met with some scepticism.

"I'm unaware of any evidence that supports this hypothesis," insists Dr McGregor. "I mean, what happened to the Atkins? People who try diets like this might lose weight at first - because they are watching what they are eating - but they'll put it back on again."

While doctors may be right to question such a radical diet, Dr Johnson's plan does seem to have tapped into something. Internet message boards are heaving with glowing testimonials from thousands of people already subscribing to the schizophrenic eating patterns. Oddly, perhaps it is precisely because it is so extreme that Dr Johnson's "feast and famine" approach appeals to the dieters of 2008 - in a culture of size zeros and rising obesity levels, it doesn't seem all that crazy.

Day by day: the diet

I'm not desperate to lose weight, but with summer on the way, the thought of baring arms, legs or anything in between is enough to make me wish that the needle on the scales hovered a few lines lower. I decide to start on an "up" day, meaning that I can eat anything I want. Turns out, I want a lot of food, most of it fattening.

My usual breakfast of porridge or toast is eschewed in favour of a cinnamon roll and two pains au chocolat, sushi lunch swapped for a giant panini and crisps, and modest dinner replaced with an Indian banquet, followed by a box of chocolates. I could get used to this diet.

I wake up the next day nursing a "food hangover", complete with dry mouth, gurgling stomach and slightly sick feeling. If this continues, avoiding food should be a doddle.

Needless to say, it doesn't last. At 10.30am I can smell toast, and it's a damn sight more appealing then the strawberry meal-replacement shake Dr Johnson recommends I "sip throughout the day". By 4pm, I'm grumpy, tired, shaky, and more than a little hungry.

I'm allowed a meal in the evening, as long as it is less than 250 calories, and leaf through Dr Johnson's recipes in search of something edible. No such luck. I settle for a broccoli omelette, which wouldn't fill the gap in a hollow tooth. I sneak in a cracker with jam before bed, which sends me over my calorie limit. This is nowhere near as fun as yesterday.

The cycle continues for the rest of the week - I feel too full one day, and too hungry the next. When I finally step on the scales, I find I have lost 2lbs. I'm pleasantly surprised, but I won't be sticking with it. Dr Johnson is right about one thing - it doesn't feel like a diet. Shame it doesn't feel great either.