The fat and the thin of it
A study published this week argues that the controversial Atkins diet does help you lose weight - and is safe. Ian Sample reports
Friday May 23, 2003 The Guardian
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It's little more than a month since Dr Robert Atkins, the millionaire diet guru, died from head injuries after slipping on ice outside his New York clinic. His big idea, that slashing carbohydrates while feasting on high-protein foods, was the answer to the western world's spiralling fat epidemic, drew criticism as soon as it was first published in 1973, and has remained controversial ever since.
But this week, arguably the best evidence that the diet is not only effective, but safe, too, was published in a respectable medical journal. So is it time for the establishment that united against him to eat its words?
Until now, most scientific studies apparently supporting the benefits of Atkins' diet have largely been rubbished. For them, too few studies compared people on the Atkins diet with those on more conventional diets, or on no diet at all.
Without the comparison, it was impossible to work out just how effective, if at all, the Atkins diet was. But whatever the scientists thought about it, the Atkins philosophy has proved a remarkably attractive one. In the 30 years since it was first published, Dr Atkins New Diet Revolution has sold more than 10 million copies and been read by some 30 million people. And in recent years the diet has soared to new heights of popularity, inspired by the example of celebrities like Jennifer Aniston, Geri Halliwell, Minnie Driver and Renee Zellweger, all of whom have been linked with the low-carb philosophy.
Countless women all over the world now routinely sit down to meals consisting almost entirely of meat, eggs and cheese, in the hope of a miraculous weight drop. But can it really be true that eating this way can make you thinner, without any cost to your health?
The publication of two papers in the New England Journal of Medicine this week prompted headlines that suggested the confirmation Atkins had long wished for had finally arrived. First, a team at the University of Pennsylvania tested the effect of the Atkins diet against a conventional low-fat diet on 63 obese men and women over the period of a year. Meanwhile, another team in Philadelphia followed 132 severely obese people on either a standard low-fat diet, or an Atkins-like low- carbohydrate diet.
At first glance the results do indeed appear convincing. Both studies found that those on the low-carbohydrate diet lost more weight in the first six months - six or seven kilograms as opposed to two or three kilograms. Philadelphia's study found that the levels of a blood fat called triglyceride had also dropped. Newspaper headlines enthusiastically heralded the holy grail of diet plans.
But as a more detailed reading of the research reveals, they may have been premature. At the end of a year, the group tested in Pennsylvania showed no difference in weight loss, regardless of the diet they had been on. The results of both tests, it seems, should be treated with caution. "My take on both papers is that they didn't recruit enough people and there was a large drop-out rate, which makes it very difficult to read anything into them," says Robert Bonow, president of the American Heart Association. Nearly half of those taken on for the studies dropped out.
The Atkins diet is supposed to work like this. If you all but strip out carbohydrates from your diet, but eat lots of protein, your body is forced into an unusual situation. First of all, your body will stop releasing floods of insulin, the hormone Atkins referred to as the "fattening hormone". The result, the argument goes, is that less fat is stored in the body. There's a secondary effect, too. Load the body full of protein and you force the kidneys to work to get rid of them. This takes energy. Without the carbohydrate to power the process, the body starts breaking down fat to make fuel. That, at least, is the idea.
It is true to some extent. Talk to someone who has been on the Atkins diet for long enough and you will likely smell pear drops on their breath. It's the result of compounds called ketones that are released when fat is broken down in the body. The condition is called ketosis and often makes people feel nauseous. Which is a side-effect that can help people lose weight, simply by putting them off their food.
But nutritionists reckon this only contributes a tiny amount to any weight loss. The real reason the diet works, they say, is because it is so horrendously dull. The fact that people dropped out of the diet studies, and typically fail to keep going with the Atkins diet in real life, too, is exactly what you would expect, they argue.
"The diet works because you are simply not eating as many calories," says Toni Steer at the Medical Research Council's Human Nutrition Research Unit in Cambridge. "It's simply too monotonous. If you sit down and try to eat just a plate of meat, it's very difficult to do it in any quantity. And at the end of the day, a calorie is a calorie, however you get it."
What's more, the Atkins diet is still considered to be likely to cause medical problems. As the body strives to break down the extra protein it has been landed with, it produces by-products that make the blood more acidic. To neutralise it, the body starts excreting calcium, which would otherwise go into making bones. "Since women are more susceptible to bone-wasting conditions like osteoporosis, losing calcium is a big issue," says Sarah Stanner of the British Nutrition Foundation.
That the Atkins diet can potentially cause medical problems is not a new idea and many people - mostly women who give the diet a try - are aware of this. But why do they take the risk knowing there are healthier ways of dieting? "People today want to see quick results. They want dramatic weight loss in a short time. They see celebrities in the media who appear to have transformed themselves, and that contributes to it," says Steer.
"People are more motivated by cosmetic issues than health issues," says Stanner. "If they think they are going to lose weight, they might be motivated by that even if it's not the best thing for their health."
Calcium loss is just one of the problems nutritionists are concerned about. The Atkins diet is also low in fibre, the results of which are well known. "Because it's low in fibre, people complain of diarrhoea or sometimes constipation," says Stanner.
Fruit and vegetables are not something the body can live healthily without for long. "If you don't eat fruit and vegetables, you are excluding a lot of essential minerals and vitamins from your diet. And we know that consuming these foods reduce your risk of cardiovascular disease and cancer," says Steer. The problem is that long-term studies to find out if going without these foods does lead to more heart disease and cancer have not been done. "We still need to know more, and until we do no more, I'm not going to recommend the Atkins diet," says Bonow.
One of the biggest problems is that many of those trying to lose weight are obese people who are susceptible to diabetes. Because diabetes slowly but steadily damages the kidneys, the extra burden of a high-protein diet can be enough to speed up the kidney damage. "If you've got that early, slow kidney damage going on, and many diabetics don't know it, a high-protein diet is going to be a problem," says Bonow.
So the jury remains out on Atkins' big idea, and the prognosis for the future of dieting is rather more mundane. According to Bonow, to lose weight and keep it off, you need three things: motivation, diet and exercise.
And unless you want to lose weight fast, only to put it all back on again in a few months, your best bet, he says, is to choose a reduced- fat diet. "No one has ever shown that with the Atkins diet you can both lose weight and maintain that loss. But with reduced fat diets, you can do this.
"The initial weight loss is easy. It's maintaining it over the course of time that's more difficult. Studies that look at people who are successful at losing weight and maintaining weight loss for five to 10 years are primarily people who are on a reduced-fat diet and exercise more," he says.