What scientific studies say about low-carb diets
Is the Atkins diet a sound choice? According to the following studies, the answers are yes and no:
Dr. Eric Westman, director of the Duke (University) Diet and Fitness Center, conducted the first scientific study of the Atkins diet. It appeared in the June 2002 issue of the American Journal of Medicine. Fifty subjects were put on a very low-carbohydrate diet that allowed them to eat an unlimited amount of meat and eggs, two cups of dressed salad and a cup of low-carbohydrate vegetables. The average subject lost approximately 20 pounds and experienced improved cholesterol levels. However, 20 percent of participants dropped out before the end of the six-month study. Westman also expressed doubts about the diet's long-term safety.
University of Cincinnati researcher Bonnie Brehm studied 53 obese women for six months and reported her results in the Journal of Clinical Endocrinology and Metabolism last year. The subjects were divided into two groups: one following the low-fat diet of the American Heart Association - which financed the study - and the other following Atkins.
Participants met with a dietitian weekly. Although the Atkins patients lost twice as much weight, they had trouble staying on the diet because they missed eating fruit, juice, bread and pasta, Brehm said in a phone interview.
Despite the diet's effectiveness, she said, "I have my doubts that it's safe over the long term. It's low in calcium, low in fiber, and it's cutting out one of the big sources of vitamins and phytochemicals: fruits and vegetables." Phytochemicals are substances in foods that, while they have no nutritional value, might help protect against various diseases, including cancer and heart disease.
Gary Foster of the University of Pennsylvania School of Medicine randomly assigned 63 overweight men and women to the Atkins diet or a conventional low-calorie, low-fat diet. The Atkins dieters were given a copy of Atkins' book to follow, but otherwise they were on their own.
The yearlong study, published in the New England Journal of Medicine in May, found that the Atkins subjects lost more weight at three months than the conventional dieters, but by the end of the yearlong study, the difference in weight loss was insignificant. About one-third of the participants dropped out before the study was completed.
"Based on the few studies, it looks encouraging, but we do need longer and more comprehensive studies before we change public-health recommendations," he said in a phone interview.
Another study, also published in the New England Journal of Medicine in May, involved 132 severely obese subjects who fol lowed low-fat or low-carb diets. The low-carb group lost more weight than the low-fat group. However, 40 percent of participants dropped out before the end of the trial. The principal investigator was Dr. Frederick Samaha.
In April, the Journal of the American Medical Association published a systematic review of studies of miscellaneous low-carbohydrate diets, concluding that there was "insufficient evidence to make recommendations for or against the use of low-carb diets." The study also found that weight loss in low-carb diets was related to reduced calorie intake, not reduced carbohydrate intake.
- Fran Henry
The skinny on low-carb diets
Plain Dealer Reporter
They'll tell you how many pounds they've lost with out feeling hungry, and they'll tell you how many people they've converted. But when Atkins dieters get together, it's hard to tell if they're talking about a diet or a religion.
Such is the enthusiasm engendered by the high- protein, low-carbohydrate weight-loss program that Dr. Robert Atkins launched in his 1972 book, "The Diet Revolution," and its 1992 update, "The New Diet Revolution," which has sold in excess of 10 million copies and has been on The New York Times' best-seller list nearly seven years.
Despite unattractive side effects commonly associated with the Atkins plan - "fruity" breath, frequent urination and sluggish bowel movements - about 30 million Americans have been seduced by the diet's irresistible promise of weight loss without hun ger, according to the Atkins Physicians Council, which provides guidance and education about the diet.
"It's an exciting craze," said Dr. Stuart Trager, a Philadelphia orthopedic surgeon who is the council's spokesman and chairman.
"It's bringing people together to teach them to make better nutritional choices."
While the Atkins regimen has dieters salivating at the thought of unlimited steak, merchants are salivating at Atkins' profit potential.
Specialty food stores, supermarkets and even drugstores are peddling low-carbohydrate foods, including pricey Atkins products. Restaurants and fast- food outlets alike are beginning to dish out Atkins-acceptable menu items - such as Hardee's Thickburger, which is "wrapped" in iceberg lettuce rather than a bun; and Donato's "protein crumble" doughless pizza. Chef Roger Thomas, owner of Akron's Piatto restaurant, recently began to offer Atkins-style entrees when customer requests increased from a couple a week to six or eight a night.
But what's been missing from the ear-splitting Atkins buzz are discussions about the safety of the diet's unorthodox approach and its long-term consequences.
Atkins promoted the diet for 30 years before it underwent scientific scrutiny, a detail minimized by the Atkins empire.
"Before 2002, the diet was based on Dr. Atkins own personal observation, what he saw," Trager said. "He didn't claim that that was scientific evidence, but reporting on his own experience was very valuable. When Atkins was able to fund research, he did."
Researchers worry about long-term effects
A physician unrelated to the Atkins empire encouraged Atkins to seek scientific evidence for his diet.
"I was the guy who went up to Atkins and said, 'You've got to study it,' " said Dr. Eric Westman, director of the Duke (University) Diet and Fitness Center, in a phone interview.
Atkins agreed, Westman recalled. In short order, Westman embarked on a six-month study financed by an unrestricted grant from the Atkins Center for Complementary Medicine. Terms of the study allowed Westman to operate independently of Atkins. Westman concluded that the diet was effective for weight loss and improving cholesterol levels, results published in the July 2002 issue of the American Journal of Medicine.
While Westman said he was impressed by the diet's results, his doubts about the diet's safety were unabated.
"The jury is still out that it's healthy," he said. "Science says that for a six-month period, there's no terrible downside, but the number of people enrolled in the study is inadequate."
Despite his reservations, Westman has added a low-carb, high- protein diet option at the Duke diet center, where patients are under close medical supervision.
Three subsequent studies and a review of miscellaneous weight-control studies also found the diet to be an effective tool for weight loss. But all the researchers, including Westman, had lukewarm enthusiasm for the regimen. All suggested that long- term studies would be necessary to establish total safety.
(See accompanying story for details on previous studies.)
A common theme throughout the studies is the difficulty of maintaining the diet over the long term.
Dr. Gary Foster, clinical director of the Weight and Eating Disorders program at the University of Pennsylvania, expects to gain a clearer picture of Atkins' safety through a new five-year study, financed by the National Institutes of Health. The 360 male and female subjects will be assigned to the Atkins diet or a high-carbohydrate, low-fat diet based on behavior modification. Two groups of dieters will be treated for two years each.
"We'll have a lot more people, a lot more measures, not just cholesterol and weight, but also the effects on bone mass, kidney function and ability to exercise," he said. The Atkins dieters will not be given copies of the Atkins book, as they were in Foster's previous study.
Many who believe they are following the Atkins diet might not be, said Barbara Moore, president and CEO of former Surgeon General C. Everett Koop's organization, Shape Up America!
A survey commissioned by Shape Up America and reported in December found that more than 67 percent of Atkins dieters did not know tomatoes are rich in carbohydrate, 47 percent did not know apples are high in carbohydrate, and 14 percent thought steak is a carbohydrate.
"Confusion is everywhere, not just among dieters," Moore said. "It makes strict adherence to the diet nearly impossible."
Low fat vs. low carbs
The Atkins council maintains complete confidence in the diet, despite the reservations expressed by the various researchers.
"It's a nutritional strategy that can be followed safely without close medical supervision," said Trager, of the Atkins Physicians Council.
"We know the low-fat approach has failed. Obesity results in 300,000 deaths a year in the United States. For many people who were unable to limit consumption, this allows them to manage health and weight. Atkins works in the real world. It's not about what works in the lab or what works for the heart patient."
Dr. Paul Robinson, however, is concerned about the diet's effect on heart muscle. A University of Missouri associate professor, Robinson studied the August 2000 death of a Missouri teenager who collapsed at school and died of cardiac arrest on the eighth day of her second go- round with the Atkins diet.
The teenager had no history of heart disease, Robinson noted in an article published in the Southern Medical Journal in September 2002. Her initial electrocardiogram, he wrote, "revealed ventricular fibrillation, an unusual presenting arrhythmia in a 16-year-old adolescent without underlying cardiac disease or electrolyte imbalance." The girl's electrolyte levels were found to be critically unbalanced, a result of excessive urination common among high-protein dieters, he said in a phone interview.
"Muscles contract based on electrolyte shifts . . . The heart's a muscle, and if you get abnormal levels of electrolytes, it can create abnormal heart rhythm."
The Missouri case, he said, leads him to believe that "we're having lots of near misses that we don't know about."
Trager called Robinson's article "anecdotal reporting."
The most vocal critic of Atkins is the Physicians Committee for Responsible Medicine, a nonprofit Washington-based organization that promotes preventive medicine but is somewhat controversial. The committee says the diet's low-fiber and high- fat content increases the risk of colon cancer, cardiovascular disease, impaired renal function and osteoporosis - allegations Atkins vehemently denied until his death in December from a fall-related injury.
The committee, which maintains an online registry of health problems related to high-protein dieting, has asked the government to warn the public about the dangers of such diets in the next version of the Dietary Guidelines for Americans, which is being updated for an anticipated 2005 version. It is also asking the U.S. Centers For Disease Control to investigate "what problems, what fatalities, could be or could not be linked to this kind of diet fad."
Other major health organizations have not taken an official stand on the diet's safety and efficacy.
For now, at least, dieters are focusing more on results than research.
"Atkins is for people who can't control themselves," said Solon nurse Cindy Zito, 49, who attends a low-carb support group at Sugar Freedom, a Lyndhurst low-carb food store. She's been on and off the diet for six years. "Every time I want to get myself under control, I jump on it."
If she deviates from the diet, she said, her carb addiction kicks in. "I crave, and I can't stop eating. Once in a great while, I'll eat half of an apple dipped in peanut butter. I know after I've eaten it, I'll start craving, 'What can I eat next?'
"Every morning, I ask God to give me strength to resist the wrong food."
Another support-group attendee, Jeff Lee, 60, of Lyndhurst said he decided to try Atkins when his weight peaked at 213 pounds. He lost 9 pounds his first 10 days on the diet. His goal is 160 pounds.
"And I'm not hungry," he said. "I haven't been hungry since I started."
And that explains the ongoing success of Atkins, said Shape Up America's Moore.
"Americans want the magic potion, something quick and easy," she said. "But it isn't what we recommend."
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