Nutrition Hotline
by Suzanne Havala Hobbs, DrPH, MS, RD
This issue’s Nutrition Hotline addresses the effectiveness of and the health concerns surrounding popular low-carbohydrate diet plans.
QUESTION: “Are high protein, lowcarb diets a good idea for weight control? They seem at odds with a vegetarian diet.”
ANSWER: True or false? Carbohydrates are bad for you.
You might guess “true” based on what we see in supermarkets and in advertising these days. For all the attention carbs are getting, it’s as if a scientific panel had announced they’re deadly.
But nothing about the science of sustainable eating practices actually changed to prompt the low-carb craze that has made the Atkins diet so popular. Nevertheless, consumer perceptions—and buying habits—have changed dramatically. How that happened says a great deal about how Americans get and interpret nutrition information.
The late Dr. Robert Atkins published his first book in 1972. His notion that you can lose weight by limiting carbohydrates rather than fat had an immediate and enduring appeal. It allows adherents to follow a hyper-American diet of bacon and egg breakfasts, double cheeseburger lunches, and steak dinners—and lose weight, too. That the diet directly contradicts years of advice from nattering nutritionists to cut the fat makes it all the sweeter.
The popularity of low-carb diets surged after a provocative July 7, 2002, article in The New York Times Magazine. Atkins quickly labeled the article a validation of low-carb dieting.
Eleven hundred words into the article comes a pivotal sentence:
“If the alternative hypothesis [that carbohydrates are what make us fat] is right—still a big ‘if’—then it strongly suggests that the ongoing epidemic of obesity in America and elsewhere is not, as we are constantly told, due simply to a collective lack of will power and a failure to exercise.”
Did you catch that? “Still a big ‘if’?”
The remainder of the 7,800-word article is constructed atop that “if,” a two-letter word upon which the worlds of fad diets and food marketing have turned during the past 22 months.
But low-carb dieting has not been vindicated.
It’s true that you can lose weight on the Atkins diet or other controlled-carb diets. But you can also lose weight on high-carb, low-fat diets, rice diets, and grapefruit diets. In fact, I’m certain you can lose weight on pine bark or Pez diets, too.
Research suggests that weight lost on the Atkins diet, as with other diets, is the result of cutting calories, not carbs.
While it may sometimes be desirable, and medically beneficial, to shed weight over a short period of time, what most people need is an enjoyable and sustainable eating plan that helps them control their weight and promote overall health over their lifetimes. Inaccurate nutrition news reporting and misleading hype has led many people away from that goal during recent months.
Here’s an example:
The results of two studies of low-carb diets involving a small number of people were published in May 2003 in the New England Journal of Medicine. News stories about the studies got a lot of media attention, often with headlines that echoed one the Associated Press put on its widely used story: “Pair of Studies Vindicate Atkins Diet.”
But here’s the headline the Reuters news service used: “Atkins Diet May Be No Better Than Just Cutting Fat.”
What gives?
Both studies found that, at six months, people on a low-carb diet lost more weight than those on a conventional low-fat diet. But after one year, the longer study found the low-carb dieters gained back more weight, leaving no significant difference in the amount of weight lost between the two approaches.
Authors of both papers cautioned that limitations of the studies, including the small number of study participants and short length of time they were followed, made conclusions difficult to draw. They also cited multiple concerns about the long-term healthfulness of low-carb diets, since most are low in fiber and high in protein and saturated fat, factors associated with increased risk for heart disease, cancer, diabetes, and other ills.
The authors of both studies said more research was needed to determine the long-term safety and effectiveness of low-carb diets. This is the final sentence of the conclusion of the six-month study: “Future studies evaluating long-term cardiovascular outcomes are needed before a carbohydrate-restricted diet can be endorsed.”
And yet, here’s part of what the Atkins Nutritionals, Inc., website said about the two studies: “… [T]hese significant results should make physicians and the rest of the health care community more comfortable recommending the low carbohydrate alternative to their patients.” (See www.onthetable.net for links and more details on these and other materials.)
LESSONS TO LEARN
- Read beyond the headlines. Look for nuances and contradictory details that don’t get into the headlines.
- Dig deeper. If you’re considering a dietary change based on news you’ve read or heard, make an effort to learn more. You can find more details about most research studies by doing an Internet search using the author’s name. You might be surprised at how often researchers’ summaries of their papers come across differently than the news stories do.
- Be skeptical. If it sounds too good to be true, it probably is—especially in nutrition news.
I spoke to Dr. Eric Westman, a Duke University medical researcher frequently cited by the Atkins marketing machine for his research on low-carb, high-protein diets. I asked if he has any hesitation recommending an Atkins-style diet long-term.
“Of course,” he said. “I’ll make no statement about it beyond six months.”
Westman said more direct study of the diet was needed before any statements can be made about its safety and effectiveness. For anyone contemplating following the Atkins diet for longer than six months, Westman said, “Only do it under the supervision of your doctor or health care provider.”
For now, he recommends a Mediterranean-style diet for the long run. He feels the approach taken by Harvard researcher Walter Willett, author of Eat, Drink and Be Healthy, is sensible.
I agree. It’s a diet plan—a lifestyle, actually—that draws from decades of research following tens of thousands of people.
For non-vegetarians, it emphasizes fish over other forms of meat. For vegetarians, here’s the translation:
Cut down on portion sizes and exercise more—much more. Trade in the refined carbohydrates in white bread, cakes, and soft drinks for foods rich in complex carbs in their natural state—foods like beans, oatmeal, and whole-grain breads and cereals. Eat lots more vegetables and fresh fruit. Get your fat from olive oil, avocado, nuts, and seeds instead of butter and hydrogenated oils. Get your protein from beans, nuts and seeds, vegetables, and grains. And make it a way of life.
