Is the Atkins diet safe?

The Atkins diet, which is based on consuming high levels of protein and low levels of carbohydrate, has become a popular weight-loss approach among celebrities and the public. Two studies have been publicised as supporting the diet and confirming the weight-loss ability. But is this really the case? Are there still safety issues and is the diet a suitable approach for long-term weight loss?

What were the headlines?

Coverage of the two studies appeared in a range of publications. Headlines included "The fat and the thin of it", "Atkins diet is more effective and healthier than rival regimes", "High-fat diet confounds experts", "Controversial dietary plan proves healthier than expected", and "Atkins diet 'is beneficial and twice as effective as rivals'".

Most reports took the stance that together the studies prove the validity and safety of the high-protein diet, but although this may seem the case at first glance, a closer look at the research uncovers a different, and mostly unreported, story.

What is the bigger picture?

Both studies were published in the New England Journal of Medicine (NEJM). The first was conducted by the Philadelphia Veterans Affairs Medical Center, where 132 severely obese patients were randomly put on either a low-carbohydrate diet, or a low-fat diet, for six months. The Atkins dieters limited their carbohydrate intake to 30g a day and received counselling on healthy types of fat, such as omega-3 fatty acids. The low-fat dieters were put on a calorie-controlled diet, with no more than 30 per cent of total calorific intake from fat.

Only 79 people managed to complete the six-month trial. Low-carbohydrate dieters lost an average of 13 pounds, compared to four pounds for low-fat dieters. No significant changes in cholesterol or blood pressure levels were noted in either group, but the low-carbohydrate consumers did reduce their levels of triglycerides (blood fats) by an average of 20 per cent, compared to only 4 per cent in the other group.

"This study demonstrates that a low-carbohydrate diet can have beneficial effects in treating obesity," said senior investigator, Dr. Samuel Klein. "Additional research is needed to understand why subjects assigned to a low-carbohydrate diet lose more weight than those assigned to a conventional diet and to evaluate the long-term efficacy and safety of low-carbohydrate diet therapy."

The second study was carried out over one year, led by researchers at the University of Pennsylvania School of Medicine. Only 63 obese men and women took part, and were either assigned to a low-fat diet or the Atkins approach. All the participants met with a registered dietician at the start and then at three, six and 12 months into the programme.

They discovered that at three months Atkins dieters had lost an average of 14.7 pounds, compared with 5.8 pounds; at six months the losses were 15.2 pounds and 6.9 pounds respectively, and at one year they'd lost an average of 9.5 and 5.4 pounds. At one year, Atkins participants had greater increases in HDL cholesterol (18 per cent, compared with 3 per cent) and greater reduction in triglycerides. There was no change in either group in levels of bad (LDL) cholesterol.

"These preliminary data suggest that weight losses will be comparable to conventional approaches over a one-year period, but there may be more favourable effects of a low-carbohydrate approach in term of triglycerides and HDL (good) cholesterol," said Dr. Gary Foster, one of the researchers.

Although on the surface both studies appeared to show benefits from the Atkins diet, delving deeper into the details reveals a number of negative points. Most notably:

* Both studies were very small.
* Both used obese, or severely obese, participants, which isn't representative of the average UK dieter.
* There was a high drop-out rate, suggesting that people found the Atkins diet hard to stick to.
* They didn't address the harmful effect the diet could have on the kidneys.
* The difference between the weight losses at the end of the studies wasn't really that different.

Dr. Amy Joy Lanou, director of the Physicians Committee for Responsible Medicine in America, was quick to point out health dangers of the Atkins diet. "A Harvard study published earlier this year in the Annals of Internal Medicine showed that high-protein diets may cause permanent loss of kidney function in anyone with reduced kidney function. Other studies have shown that meat-heavy diets significantly increase one's risk of colon cancer and osteoporosis," she said.

Dr. Foster acknowledged the potential problems and said they're planning a longer five-year study. "This larger study of 360 participants will help us more fully assess the benefits and risks of low-carbohydrate diets on bone mass, kidney function, arterial function and exercise tolerance," he said.

What does this mean?

Brigid McKevith, a nutrition scientist at the British Nutrition Foundation (BNF), said, "We welcome the fact that the Atkins diet is being studied scientifically and that randomised controlled studies have been carried out, because it's very popular with the public."

However, she expressed concern at the small number of people studied and the high drop-out rate, as well as a number of key safety questions that are still left unanswered. "There are several potential problems with the Atkins diet. These include long term bone health, as with a very high protein intake the excretions of calcium increase, so there could be implications for the health of bones," she explained.

"There could be difficulties for people who have an underlying problem with their kidneys or liver, because it would be putting more strain on those organs, and problems in terms of heart disease too, as it's a diet very low in fruits and vegetables. Also, it's very low in fibre, so in terms of digestive health, it's not in keeping with our fibre and complex carbohydrate recommendations."

Belinda Linden, head of medical information at the British Heart Foundation, holds similar views. "The new studies do not indicate a dramatic weight loss for excessively obese people," she said. "Previous studies have shown that weight loss from the Atkins Diet may involve muscle loss rather than body fat. Another potential problem is that it is so far unclear from studies whether weight loss is sustained over a longer period than six months. One of the studies shows no significant difference at 12 months."

She added that, "With minimal fruit and vegetables included in the diet, it holds serious implications for coronary heart disease and cancer. Diets need to be varied to protect against these conditions - and this one isn't. This diet requires further long term and larger studies before its effectiveness can be confirmed."

What does this mean to me?

"My general feeling about the Atkins diet is that, like anything that severely restricts your calories, you'll lose weight. In the short term, if you want to do it for two weeks and lose weight, it probably won't do you any harm," said Dr. Paula Franklin, from Bupa Lighten Up.

However, she warned, "What you need to do in order to be healthy in the long term is to ensure your body has all the nutrients it needs. So, a long-term diet that doesn't include many fruit and vegetables (ie the Atkins) wouldn't be good."

"If you want to be a healthy weight in the long term, the best approach is really lifestyle change," said Dr. Paula Franklin. Fad diets lure people with a quick fix cure, but, says Dr Franklin, "there's no magic with weight loss, and unless you change both what you eat and what you do, you'll put weight back on again."

Summary

The Atkins diet is a very different approach to the recommended weight loss methods and the general consensus is that it's important more research is done into the long-term health effects, as at the moment they're currently unknown.