News that detoxing is potentially dangerous will have caused ripples of panic among those who rely on it for inner cleansing and occasional inch loss. Dawn Page, a 52-year-old mother of two from Oxfordshire, made headlines when she received more than £800,000 after suffering permanent brain damage while on a detox diet that instructed her to reduce her salt intake and consume large amounts of water.

Long before this case, reputable dieticians were questioning the effectiveness and safety of detoxing. A detox diet can last anything from 48 hours to 21 days, and most involve drinking two litres or more of water a day, along with dandelion coffee and herb teas that are thought to help expel environmental nasties. Most also recommend additional fluids - carrot and apple juice are favourites because of their “digestion boosting” properties - and some allow unlimited consumption of raw fruit and vegetables, but little else. Catherine Collins, chief dietician at St George's Hospital in London, says she has seen dozens of people with debilitating detox side effects, usually as a result of consuming more water and less salty food, often in conjunction with increased activity.

One was a 23-year-old patient who had slipped into a four-day coma as a result of hyponatraemia (water intoxication, which causes blood sodium levels to plummet and the brain to swell) induced by a three-week detox diet. Too much fluid and too little dietary sodium mean body salts, or electrolytes, in the blood become dangerously diluted. “Sticking to a detox regimen for a day or two won't be harmful for most people - neither will it have any effect on their long-term health - as there is no scientific basis for it,” Collins says. “But when detox plans promote longer periods of severe dietary restriction, which many do, they can cause problems.”

So, with detox phobia rife, is there a more moderate and less risky alternative? Some scientists think so and are advocating an approach called alternate-day fasting (ADF), which should appeal to those who have trouble sticking to a harsh dietary regimen in the first place. For most of us, diets are a calorie seesaw: you cut down your intake with grim determination one day, only to be ravenously hungry the next. And, according to the scientists who have studied ADF, this may be no bad thing. Their admittedly controversial research has shown that restricting calories for 24 hours and reintroducing them the following day will not only help you to shift pounds and fat cells, but also to live longer.

A quick internet search reveals there are hundreds of visitors to ADF and “intermittent-fasting” chat rooms, along with thousands of sites detailing the purported benefits of this bizarre trend for self-imposed semi-starvation. In America, a raft of books on the subject, such as The Alternate-Day Diet and The QOD Diet: Eating Well Every Other Day, have further raised its profile and appeal. “Alternate-day fasting lets you focus your hunger in manageable periods,” says Brian Delaney, author of The Longevity Diet. “You are not a little hungry all the time, like you are on a normal diet, but you are very hungry for a little time.” And with a growing body of scientific backing for its health benefits, AFD is, potentially, more than just another diet fad.

Recently, nutritionists at the University of California found that eating half as much as usual every other day could shrink fat cells and boost some of the mechanisms that break down fat. Krista Varady and her team put some mice on a full alternate-day fast, while others were allowed to eat half as much as usual on their fasting days. The results showed that, while the first group lost more weight, the fat cells of all the dieting mice shrank by at least 35%. Another study, published three years ago in the American Journal of Clinical Nutrition, showed that people who followed the ADF diet for just three weeks lost an average 2.5% of their body weight and 4% of their body fat.

Even if you fast one day, then are so chew-off-your-arm hungry the next that you gorge on highly calorific goodies, there seem to be health benefits. In a study carried out at the National Institute on Ageing, American scientists allowed mice to eat nothing one day and trained them to tuck into as much food as they wanted during the next 24 hours. Although they were too greedy on their eating days to shed weight, they still had improved insulin sensitivity - meaning they cleared sugar from the bloodstream more efficiently, a vital factor in preventing diabetes - and a longer life span than the mice who ate regular meals every day.

So, how does ADF work? Like our hunter-gatherer ancestors, who spent days searching for food and ate only intermittently, we are genetically programmed to adapt to cycles of fasting and feasting. Scientists say the temporary withdrawal of food for short periods appears to stress the body in a positive way, so that a gene called Sirt1 is switched on. This gene is also activated by resveratrol, the antioxidant present in red grapes and wine that is known to ward off heart disease and help the body to use fats in the bloodstream for energy.

Not all nutritionists think ADF is the way to go, however. Some argue that it is impossible to stick to long term. In the few human studies carried out on ADF, subjects have often reported feeling tired, tetchy and hungry on the days they were required to fast. Critics suggest that those looking to lose weight do not need to subject themselves to such a harsh regimen. They point to a study by researchers at Cornell University that showed that simply restricting calories for one meal a day could help to shift pounds. When a group of people were asked to cut their usual lunch to 200 calories, they didn't compensate by eating more during the rest of the day.

Those who try ADF should bear in mind that food must be ultra-healthy, as “with no calories to spare, every bite you take needs to be packed with nutrition”, says Susan Bowerman, assistant director of the Center for Human Nutrition at the University of California, who has reviewed the trend. “There is a lot of research to be done before the animal studies that have proven it to be healthy are replicated in humans,” says Lisa Miles, a nutrition scientist at the British Nutrition Foundation. “If you have overeaten one day, then it will help to balance out your calorie intake by eating less the next, but it is not something that we would recommend on a long-term basis.”

Detox fads: the big three

Master Cleanse: Also known as the Maple Syrup Diet or the Lemon Detox, it involves drinking glasses of Madal Bal natural tree syrup mixed with lemon juice and cayenne pepper — see The Complete Master Cleanse by Tom Woloshyn (Ulysses £6.99). During the recommended 10-day fast, it is suggested that no food is consumed. Beyoncé reportedly lost 22lb on this.

Verdict: Contains too few nutrients and might be dangerous.

21-day detox: Oprah Winfrey tried it recently. Devised by Kathy Feston — it featured in her American bestseller Quantum Wellness (Weinstein £12.70) — it advocates adopting a vegan diet of whole grains, beans and legumes, and steamed or sautéed vegetables for three weeks.

Verdict: Cutting out whole food groups, such as meat, can leave you prone to serious nutritional deficiencies.

The Longevity Diet (Four Walls Eight Windows £6.99): the author, Brian Delaney, is president of the Calorie Restriction Society, a group that practises what they preach. This regimen has been shown to increase life expectancy in animals.

Verdict: Too strict — followers are allowed to consume only 1,200 calories a day.

My week of hunger

There comes a time every summer when you wish you had started on that bikini diet a little earlier. Two weeks ago, that time struck me. So, in a blind panic at the thought of baring my unprepared body by the pool, I embarked on a detox. The General Motors Diet — so called because it was invented for the overweight employees of the American car manufacturer — promises to help you shed 10lb-17lb in a week. Perfect, I thought.

It is marginally easier to follow than some other detoxes, in that each day is different. So, it’s fruit only on day one (but you can eat as much as you like), veg on day two, fruit and veg on day three, bananas and milk on day four (odd, yes), beef and tomatoes on day five (even odder), leading you to the end of the week, when you start to eat things that actually resemble meals. And there’s no sugar or alcohol.

The rules are simple, but sticking to them? Harder. I started off the week with gusto, keenly munching on copious amounts of melon, and cancelling all plans in favour of a camomile tea in front of the telly. But by day three, I caved in — felled by a vodka and tonic — and it was all downhill from there. I discovered that, if you have a normal job and social life, you can forget about doing them and a detox at the same time. Not only do you feel faint, hungry and listless — you also feel stifled, bored and boring. Much like the diet itself. So it’s sarongs and kaftans again for me this year.

Gemma Soames