Getting fast results

Eat 600 calories two days a week and lose weight. Is this a fad or cutting-edge approach, asks Helen O’Callaghan

DAILY, unending deprivation, with no let-up, is the downfall for most dieters. Now, this is contradicted by a radical approach: intermittent fasting (IF) and its more rigorous cousin, alternate-day fasting (ADF). Both buck the accepted wisdom — that one must never skip a meal. This diet advocates ‘fasting’ — reducing your calories to one-quarter of the daily recommended intake — on at least two non-consecutive days a week, and eating whatever you want on the remaining days.

With the element of sacrifice dramatically reduced, dieters on both sides of the Atlantic are saying ‘yeah, I could handle that’.

Brad Pilon, in his 2006 book, Eat Stop Eat, recommended a break from eating to give the body ‘a chance to house-keep’. But the recent interest in IF arose after Dr Michael Mosley’s documentary, Eat, Fast and Live Longer, for BBC Two’s Horizon programme last August.

Mosley said he had “always thought of fasting as something unpleasant” and that he was “not strong-willed enough to diet over the long-term”. But he went on the 5:2 diet — eating normally five days a week and eating 600 calories on each of two days. The recommended daily calorie intake for men is 2,500, for women 2,000.

On his fast days, Mosley split his 600 calories between two meals — breakfast was scrambled eggs, a thin slice of ham and black tea; dinner was grilled fish and veg. Six weeks into the diet, he had lost a stone. Soon after the programme, Mosley said the diet had worked and he’d continue it.

Dr Krista Varady, of the University of Illinois, has been researching IF for seven years and has put scores of people through trials of fasting on alternate days. In one seven-day period, they’ll have three fast days and four feed days, and vice versa for the next seven-day period. On fast days, they eat one meal — lunch — which supplies 25% of energy needs for the day. Between 12am and 2pm, participants eat a pasta dish, fruit or veg and a small dessert (cookie, crackers or nuts).

“The majority of people lose between 10-30lbs in three months,” Varady told Feelgood. “Everyone reports that the first 10 days — which comprise five fast days — are pretty rough. After that, they feel normal again — they don’t feel hungry at breakfast and dinner time.”

While dieters can eat whatever they want on the feed days, they don’t gorge.

“I assumed, if someone ate only 25% of their energy requirements on one day, that the next day they’d eat 175% to compensate. We’re not seeing that — they’re eating 110% of their needs on feed days,” she says. This may be because dieters’ stomachs shrink or they become attuned to their fullness cues.

Many religions extol fasting as a spiritual practice. The Muslims have Ramadan and, until some decades ago, Catholics fasted overnight before receiving communion. Short periods of fasting may improve health.

Standard ‘healthy eating’ advice recommends three meals a day. Yet, after five weeks on the IF regime, Dr Mosley found that, among other blood markers, his glucose and cholesterol had improved. This doesn’t surprise Dr Varady. Among 200-300 participants in her ADF trials, LDL (bad cholesterol) reduced by between 10-25% in eight weeks, triglycerides (fat found in blood) went down by 10% to 35% in eight weeks, and blood pressure also reduced in an eight- to 12-week period.

“We’re seeing really nice decreases in cholesterol, blood pressure and glucose — all indicators of cardiovascular disease risk. The ADF diet is healthy in that you’re lowering your risk of heart attack in the next 10 to 20 years,” says Dr Varady.

Eating less — as well as reducing protein intake — also lowers levels of IGF-1. High levels of this growth hormone are good when you’re in the growing phase, but not so good in later life because, when the body’s in what Mosley calls go-go mode, cells furiously burn fuel and grow too rapidly, so there’s no room for repair.

Degree of cell-proliferation can be an indicator of cancer risk. “Every time cells multiply, DNA is replicated. If this is happening a lot, there’s an increased risk of mutation in DNA. Lowering replication rate of cells lowers cancer risk,” says Dr Varady.

When, for short periods, our bodies have reduced access to food, they switch from growth to repair mode. This repair mode is “characterised by high protection against toxins and low cell division and growth,” says Professor Valter Longo, director of the University of Southern California’s Longevity Institute, who has studied Ecuadorian villagers who have a rare genetic defect called Laron syndrome.

These people have very low levels of IGF-1 — they are short in stature and seem immune to cancer. The ‘Laron’ mouse — which Longo has in his lab — has been genetically engineered to produce very low levels of IGF-1. The mouse has a 40% increased life expectancy. “Animal and preliminary human data indicate that certain type of periodic fasting can affect ageing,” Longo told Feelgood.

Increasingly, studies also suggest IF benefits the brain. “In animals, it definitely does. In humans, we can’t say definitively — studies are planned,” says Dr Mark Mattson, head of the laboratory of neurosciences at the National Institute on Ageing and professor of neurosciences at John Hopkins University, Baltimore, who also spoke to Feelgood.

Since the late 1990s, Mattson’s laboratory has maintained rats and mice on ADF diets. Mattson has found that as a result of nerve cells in their brains, they are more resistant to dysfunction or degeneration in models of stroke, Parkinson’s disease or Alzheimer’s. Mattson’s research has found that IF stimulates nerve cells to produce neurotrophic factors, one of which is BDNF, critical for brain and memory and found — in human post-mortems — to be decreased in Alzheimer patients.

Dr Daniel McCartney, lecturer in human nutrition and dietetics at DIT, says the IF diet is an important new factor in weight-loss intervention. “Data from research trials finds people tend to lose reasonably substantial amounts of weight quite quickly. And there’s evidence that what’s being lost is visceral fat — the dangerous fat around the tummy. People with reduced visceral fat are less likely to get high blood pressure, diabetes, heart disease and certain cancers,” he says.

But McCartney cites caveats. First is longevity. It’s all very well, he says, for a mouse to get a 40% increased life expectancy, when this means an extra six months. It’s an altogether different matter for humans. As we age, we lose mineral from our bones, which is why older people get osteoporosis.

“If you fast two days a week, your calcium intake may be very low on those days. Irrespective of what you do on the other days, your average weekly calcium intake might be significantly lower [than recommended]. If you have a functional lack of calcium in the diet, but an increased life span of 10-20 years, this could potentially be very bad news. You might survive for longer, but not have optimum skeletal health.”

McCartney is concerned about the consequences of the body’s tissues being broken down to make up for inadequate protein and carb intake on fast days.

“Even if you re-supply protein on subsequent days, it doesn’t necessarily follow that the protein derived from your own tissue will be readily replaced.”

This is a big issue, he says, “if you get intermittent protein depletion of structural proteins in heart muscle or bone”.

There’s a suggestion that our bodies evolved on IF during hunter-gatherer phases of history, and so we may respond well to that style of eating. But periodic fasting was a necessity for our ancestors. “We didn’t live nearly as long, so degenerative diseases like osteoporosis weren’t an issue,” says McCartney.

What worries him about IF diets is the ‘you can eat what you want on feed days’ message. In trials, Varady found participants who ate a high-fat diet on feed days got the same protective heart benefits as those who consumed low-fat diets on theirs. But what about the micro-nutrient content of the diet, asks McCartney? What about mineral and vitamin intake? What of the fact that 50% of young women already don’t get enough iron in their diet?

“By advocating fasting on two days and anything you like for the remaining days, by not giving guidance on how to optimise mineral and vitamin intake on days when you eat … that’s a problem,” he says.

Are there side-effects to IF? Varady’s dieters feel “really strong feelings of hunger — an empty-stomach feeling”, which stop bothering them after they get used to the regime.

Dr McCartney expects dieters might feel tired and cold, particularly in winter, and their concentration may be lower.

Who should avoid IF? While moderate calorie restriction (cutting down by 500-600 calories) — coupled with plenty of exercise —

works for people with diabetes, IF-style diets are a no-no for diabetics. They should also be avoided by people who have anorexia, by pregnant or breastfeeding women, and by those planning a pregnancy. Nor are they good for children, adolescents or sports people, says Dr McCartney.

At the University of Southern California’s Longevity Institute, Longo recommends people eat a highly nourishing diet between fasting cycles — “mostly plant-based, many vegetables with some fish, proteins should be kept at 0.8g of body weight per day”.

Longo urges people to consult a physician before embarking on any type of fasting. “Fasting is much more potent than people realise,” he says.