May 21, 2003 -- The Atkins diet rules -- at least in the short
May 21, 2003 -- The Atkins diet rules -- at least in the short term.
Compared with a low-fat diet, overweight and obese people lose more weight -- faster -- on the Atkins diet. That's the finding from two reports in the May 22 issue of TheNew England Journal of Medicine.
But is it safe over the long haul? On that crucial question, the jury's still out. And there are a lot of reasons to think the final verdict may go against the Atkins diet, says Robert H. Eckel, MD, director of the general clinical research center at the University of Colorado Health Sciences Center, Denver.
"We have to give Dr. Atkins credit for saying all along that these diets would be more effective in the speed and size of weight loss," Eckel tells WebMD. "But our worries over the Atkins diet go way past the question of whether it is effective for losing weight or even for keeping weight off. We worry that the diet promotes heart disease. ... We have concerns over whether this is a healthy diet for preventing heart disease, stroke, and cancer. There is also potential loss of bone, and the potential for people with liver and kidney problems to have trouble with the high amounts of protein in these diets."
Even so, both of the new studies offer encouragement for fans of low-carb diets. People on the Atkins and a similar low-carb diet didn't just lose more weight than those on a low-fat diet. They also had lower levels of fats (triglycerides) in their blood. Those without diabetes had improved insulin sensitivity. And those on the Atkins diet had higher blood levels of "good" HDL cholesterol.
In the first study, Gary D. Foster, PhD, clinical director of the weight and eating disorders program at the University of Pennsylvania, studied 63 obese men and women. Half were randomly assigned to the Atkins diet -- they were simply given the Atkins book and asked to go for it. The other half were prescribed a low-fat diet. Like most dieters, neither group got much diet advice from doctors or dietitians.
Those on the Atkins diet lost significantly more weight over the first six months of the study. After 12 months, there was little difference in weight between those on the Atkins diet and those who stayed on the low-fat diet.
"The Atkins diet is a viable option that requires more testing," Foster tells WebMD. "The Atkins diet works at producing weight loss. If you are looking for weight loss, yes, it works. If you are looking for improvement in triglycerides and HDL cholesterol, yes, it works. The Atkins people stayed in the study longer: a 15% versus a 30% dropout rate. But over time, weight loss turned out to be pretty much the same as with the low-fat group.
The big question, of course, is whether the Atkins diet is safe. Eating a lot of protein is hard on the kidneys and liver. And there's some evidence that a high-protein diet promotes bone loss.
"This was too small and too short for a safety study," Foster says. "You need measures of kidney function, liver function, bone mass -- and that is exactly what we are doing right now in a larger study."
In the other NEJM report, a team led by Frederick F. Samaha, MD and Linda Stern, MD, of the University of Pennsylvania and the Philadelphia VA Medical Center studied 132 severely obese men and women. These people were not healthy -- they had an average body-mass index (BMI) of 43 and weighed an average of 289 pounds.
These people got a lot of input from experts in nutritional counseling. Half were randomly assigned to a low-carb diet of no more than 30 grams per day of carbohydrates (the Atkins diet begins with no more than 20 carb grams a day for a short induction period, gradually increasing until a stable weight is reached). The other patients were put on a low-fat diet with no more than 30% of calories from fat.
"Only a few in either group lost 10% or more of their body weight," Samaha tells WebMD. "This was a really tough group of patients who were very severely overweight. They had failed to lose weight on many previous diets. It was a tough crowd to lose a lot of weight. But those in the low-carb group did lose significant weight."
"Some people on the low-carb diet lost significant amounts of weight," Stern tells WebMD. "Some lost more than 50 pounds. They were incredibly enthusiastic about the low-carb diet."
Like Foster, both Samaha and Stern warn that their study didn't look at long-term safety.
"If you are able to lose weight on a low-carb diet, is it really safe from the standpoint of heart attack, cholesterol, stroke, and diabetes? We don't really know," Samaha says. "But at least in the short term there were some favorable metabolic effects such as lower triglycerides, and less insulin resistance in patients without diabetes. The diet itself may have contributed to these effects beyond what would be expected just from the weight loss. Still, it may be premature to recommend this to the public until we have more endpoints."
But Stern says the data give doctors one more option in dealing with obese patients who just can't lose weight.
"As a primary care doctor, I am clearly seeing a lot of severely overweight patients," she says. "Even though we don't yet have the evidence we are hoping for to show safety, our short-term results are in some ways promising. With so many patients, I have my back to the wall. They are failing to follow low-fat diets. I don't have medications that can help them. I don't want to send them for a surgical procedure. So I have been coaching people, cautiously, on low-carb diets. The results range from those who can't do it to those who are quite successful. But it is important to be cautious."
Samaha says that most overweight and obese people are eating too many carbs -- and too many fats. He says that diets should be individualized to cut back on calories from too much of both kinds of food. Stern totally agrees.
"We are the fattest people in the history of the planet," Stern says. "The take-home message here is we are eating too much food. It is a mistake just to emphasize a low-carb diet. People may think that means they can eat unlimited quantities of meat and fat. Nothing could be further from the truth. I don't want to reinvent the 40-ounce steak.
