Low-Carb Diets Work, but Safety Still an Issue

Not Enough Research to Declare Low-Carb Safe in the Long Term

From the WebMD Archives

Sept. 2, 2004 -- The Atkins diet and other low-carb diets help people lose weight -- at least in the short term. But the long-term safety of low carb diets is still an issue, Danish nutrition experts argue.

Nutrition expert Arne Astrup, MD, PhD, heads the Institute of Human Nutrition at the Centre of Advanced Food Research of the Royal Veterinary and Agricultural University in Copenhagen, Denmark. Astrup and colleagues ask in the Sept. 4 issue of The Lancet, "Atkins and other low-carb diets: hoax or an effective tool for weight loss?"

After reviewing the scientific literature, the Danish experts say the Atkins diet is no hoax. They say Atkins and other low-carb diets work better than low-fat diets -- for up to a year -- in helping people lose weight and lower their risk of heart disease and diabetes. And the diets seem safe, too. What's the catch?

"Our paper seems to be kind of an endorsement of the Atkins diet -- but not really," Astrup tells WebMD. "I say it is apparently safe."

Low-Carb Diets: Safety Issues?

Eventually, Astrup says, low-carb diets have the same problem as other diets: They're too restrictive for people to stay on for the rest of their lives.

"After six months, from six months to one year, the efficacy of low-carbohydrate diets seems to go away," he says. "After one year it is still better than low-fat, high-carbohydrate diets -- but people are regaining weight. They do this on all diets, so there is no reason to blame Atkins. This is probably due to lack of adherence."

What worries Astrup is that low-carb diets don't, in his opinion, have enough fruits, vegetables, and whole grains for long-term health.

"What we are more concerned about is that people on low-carbohydrate diets begin to complain about side effects: headache, muscle weakness, and cramps and diarrhea. This is consistent with carbohydrate deficiency," he says. "On Atkins, you are far below the minimum requirements -- 150 grams a day -- of carbohydrate. So the organism and the brain are probably suffering from the lack of glucose to burn, and that is disturbing the normal function of the tissues."


Or maybe the real problem is that Astrup doesn't understand the Atkins diet, suggests Mary Vernon, MD. Vernon is co-author of Atkins Diabetes Revolution, a member of the Atkins Physicians Council, and vice president of the American Society of Bariatric Physicians. She notes that the Atkins diet severely restricts carb intake only during the first two weeks.

"Many of the things he discusses apply only to the two-week induction period," Vernon tells WebMD. "For me, the great thing about Atkins is it allows people to find their own level of carb tolerance. You go down to 20 grams of carbs at first, then you go back up until you find your own level. People with diabetes have to go slower. But in both cases, you don't stay at 20 grams of carbs for the rest of your life. An Atkins maintenance plan would have whole grains like barley and vegetables like baked squash at various levels according to your personal metabolic needs."

Astrup says his research suggests that low-carb diets work not because they are low in carbs, but because they are high in protein. Bite for bite, lean protein is more satisfying than carbs or fats. So people who eat a lot of protein don't feel like eating a lot of anything else.

"The low-carbohydrate diet is working, but this is no reason to skip the six servings of fruits and vegetables and the whole grain that you need every day," Astrup says. "Instead of all the fat in these diets, it is better to have some of the good carbohydrates. ... That is the problem with Atkins. We are concerned that in long term, if you don't get plenty of fruits and vegetables and grain, you don't get sufficient fiber and vitamins."

Therefore, Astrup says, the best diet would include plenty of healthy carbs and a good bit of lean meat, fish, and lean dairy products.

"If you simply increase your intake of lean meat from fish, poultry, pork, beef, and the lean dairy products, which could quite easily be incorporated into a delicious, palatable diet, and you will eat fewer calories," he says. "We think it necessary to get the benefits of Atkins, the high protein, but at the same time to get more fruits, vegetables, and whole grains."


That's an interesting idea, Vernon says -- but no more than an "interesting hypothesis."

"I think more protein is not the secret. The science isn't in on this -- that is Dr. Astrup's personal slant," Vernon says. "Others feel the fat component may be important. But if you want to look at outcomes, look at the outcomes in the studies Dr. Astrup cites: People on Atkins have a better cardiovascular risk, their weight is lower, and their diabetes risk is lower. For me, this is the most potent tool I have ever found to manage people's metabolism."

Both Astrup and Vernon are eager to see more research. And with all the interest in low-carb diets, more research is sure to come. Stay tuned. Meanwhile, both Astrup and Vernon agree that an active lifestyle -- that is, more exercise -- is absolutely needed for weight loss and good health.

"Obesity is an imbalance between your genes and your environment. You cannot change your genes so you must change your environment," Astrup says. "Our main problem is we are so physically inactive we burn off too few calories every day. Increasing physical activity makes it so much easier. Then you don't need all these diets. You can just stick to some of this easy advice like 'cut portion size' and 'cut down on fat and drinks full of sugar or alcohol.' That may be enough -- if you are physically active."

WebMD Health News


SOURCES: Astrup, A. The Lancet, Sept. 4, 2004; vol 364: pp 897-899. Arne Astrup, MD, PhD, professor and head, Institute of Human Nutrition, Centre of Advanced Food Research, Royal Veterinary and Agricultural University, Copenhagen, Denmark. Mary Vernon, MD, co-author, Atkins Diabetes Revolution; member, Atkins Physicians Council; and vice president, American Society of Bariatric Physicians.
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