New Studies in 2002 Left Us Asking If High-Fat Diet Is Safe After All
By Gina Shaw
Reviewed By Brunilda Nazario
It's bad for you. No, it's good for you. It works. No, it doesn't work any better than any other diet. We're talking about the Atkins diet, of course, possibly the most controversial diet in America and one of the best-selling diet books in history. Until recently, medical opinion outside the Atkins fold was almost universal: Any diet that high in fat is dangerous -- particularly bad for your heart and likely to send cholesterol levels skyrocketing, for starters.
But recent studies have raised new questions: Could Atkins be safe and effective after all? At the American Heart Association meeting earlier this year, Duke researcher Eric Westman, MD, presented the results of a study comparing Atkins dieters to those who used an AHA "Step 1" diet: The Atkins dieters lost an average of 31 pounds compared with 20 pounds for the other group -- and they did it while improving their cholesterol levels. So should you pile your plate high with bacon, cheese, and steak?
Not so fast, say many experts. Even if early assumptions that Atkins must be bad for you were premature, the recent stampede of "maybe Atkins is good for you" headlines is just as much of a rush to judgment. In fact, even some of the authors of studies touted as supporting Atkins are nervous about the sudden public turnaround from skepticism to enthusiasm. Westman, whose research was funded by Atkins, was among the first to point out that it was a small, preliminary study that shouldn't change anyone's eating habits just yet.
"My concern is that anything that we've read recently about the Atkins diet is based on presentations at scientific meetings," says Gary Foster, MD, clinical director of the Weight and Eating Disorders Program at the University of Pennsylvania. "The few actual published studies are simple pre- and post-tests of the Atkins diet. Nobody's compared a conventional diet to Atkins in a randomized, controlled way."
That may soon change. Foster's own year-long study, the longest yet of the Atkins diet, is expected to be published next year, and he's already obtained a five-year grant from the National Institutes of Health to do an even larger, three-center study comparing Atkins to a conventional diet based on the USDA food guide pyramid. "The main outcomes we'll be following, besides weight loss, are lipid levels, bone density, kidney and [blood vessel] function, and exercise tolerance," Foster says.
So in five years, we'll probably know a lot more about Atkins -- but what do we know now? "Early unpublished data from several groups suggest that maybe Atkins isn't as harmful as we thought," Foster says. "However, all of these are small studies, and we need much larger studies with much broader, comprehensive assessments before we should change the dietary recommendations."
Atkins Diet -- It's the Calories
Volumetrics author Barbara Rolls, PhD, who holds the Guthrie Chair in Nutrition at Penn State University, offers a very simple explanation as to why people lose weight doing Atkins: They're cutting calories, even if they don't realize it. "No one has shown, in any studies, that anything magical is going on with Atkins other than calorie restriction. The diet is very prescriptive, very restrictive, and limits half of the foods we normally eat," she says. "In the end it's not fat, it's not protein, it's not carbs -- it's calories. You can lose weight on anything that helps you to eat less, but that doesn't mean it's good for you."
To be fair, the Atkins diet has gotten a somewhat undeserved reputation as an "all cheeseburgers, no vegetables" plan. Although the early "induction" phase drastically reduces carbohydrate consumption, requiring no fruits and only a very few leafy greens, that's only the first two weeks. "Induction is very severe, but then you go up the carbohydrate ladder. You may end up eating a fair amount of carbohydrates again six months down the line, although the diet really advises you to avoid some things, like white breads, white potatoes, and white rice, forever," says Foster. "People will say that Atkins doesn't let you eat fruits and vegetables, and that's inaccurate. He advises you to add fruits and vegetables and whole grains early on in the process."
But the diet still isn't balanced, says the American Heart Association, troubled by implications that it's changed its position on Atkins since the November meeting. (It hasn't.) "A high intake of saturated fats over time raises great concern about increased cardiovascular risk; the study did not follow participants long enough to evaluate this," the AHA said in a release.
So why did "bad cholesterol" levels go down for Atkins dieters in the studies? "Any time people lose weight by any means, cholesterol goes down," says Neal Barnard, MD, president of the Physicians Committee for Responsible Medicine and a leading Atkins critic. "But the idea that Atkins is a cholesterol-lowering diet -- the evidence on that is at best very mixed."
Plus, slashing carbs and gulping fat may be dangerous to more than just your heart health. Barnard points to research recently published in the American Journal of Kidney Disease, based on studies of 10 healthy people put on the Atkins diet. "Because their focus is kidney disease, they wanted to look at calcium loss. It was awful: On the induction diet, calcium losses were 65% above normal, and even on the more moderate maintenance diet, calcium losses averaged 55% above normal," Barnard says. "Osteoporosis is a bad enough problem as it is. If you do something that increases calcium losses, you're just asking for hip fractures."
So for now, the jury's still out on Atkins. "If it turns out that the diet is safe and effective, maybe we have something to learn from it," says Foster. "But we just don't know enough about it yet."
Published Dec. 26, 2002.
SOURCES: Gary Foster, PhD, clinical director, Weight and Eating Disorders Program, University of Pennsylvania • Barbara Rolls, PhD, Guthrie Chair in Nutrition, Penn State University • Neal D. Barnard, MD, president, Physicians Committee for Responsible Medicine • American Journal of Kidney Disease, August 2002. • American Journal of Medicine, July 2002. • WebMD Feature: Skeptics Think Twice About Atkins Diet
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