High-Carb Diets May Help Maintain Weight
Key Is to Choose Fiber-Filled, Unprocessed Foods
By Sid Kirchheimer
WebMD Medical News Reviewed By Brunilda Nazario, MD
Aug. 4, 2004 -- A message to the estimated 40 million Americans currently trying to control their weight by counting carbs: It's not enough to do the math; you also need to consider vocabulary.
New research shows what many health experts have long said. It's not carbohydrates, per se, that lead to weight gain, but the type of carbs eaten.
Tufts University researchers find that middle-aged people can successfully avoid middle-aged spread by eating a high-carbohydrate diet -- as long as those carbs are fiber-rich, unprocessed foods such as fruit, vegetables, legumes, and unrefined bread.
"Now that everybody is talking about counting carbs, many people believe that carbohydrates are the enemy," says study researcher Katherine Tucker, PhD, of the school's Jean Mayer USDA Human Nutrition Research Center on Aging. "But the truth is very simple: It's the type of carbs you eat that makes a difference. You need to eat more whole foods and less refined foods."
Her study, in the August issue of the American Journal of Clinical Nutrition, builds on a previous trial by her same research team published last year comparing food patterns in 459 middle-aged adults over an average of two years. The patients kept detailed food diaries and their weight and waistlines were measured throughout the studies. Based on their food choices, they were categorized into any of six "eating patterns."
Belly Fat: A Reality Sandwich?
In the first study, people eating the greatest amount of white bread and other highly refined foods gained the most belly fat, while those eating the typical "meat-and-potatoes" American diet gained the most overall weight, but it was more evenly distributed around their body than just settling around the midsection.
The new study confirms those findings, but also stresses an even more important message. To not gain excess weight during the years, focus on a diet that's rich in unrefined carbs and fibers such as "whole" foods like fruit, vegetables, legumes, and low-fat dairy and nonwhite bread. In both studies, Tucker says most people following this eating plan -- also said to reduce the risk of cancer, heart disease, and other conditions -- typically gained no weight, or had such little weight gain that it was insignificant.
"That's important, because there is a tendency [in middle-aged people] to gain more weight as they age," Tucker tells WebMD.
But that wasn't the case with those eating roughly the same number of calories each day, but whose carbs included more refined, packaged, and processed foods, or starchy vegetables such as potatoes. Their waistlines expanded three times more (about a half inch per year) compared with the group that ate unrefined and less processed "whole" foods.
Consider the Source
The take-home message, according to a noted obesity expert not involved in Tucker's research: Don't forego carbs altogether, just the bad ones.
"Many people on low-carb diets are making the same kind of mistake seen with low-fat diets in the past, namely, there's the consideration that an entire category of food -- in this case, carbohydrates -- is unhealthy," says David Ludwig, MD, PhD, director of the obesity program at Children's Hospital in Boston." Just as we know there are good fats and unhealthy fats, there are good carbohydrates that are rich in fiber, and less helpful carbohydrates such as white bread, excessive intake of potato products, refined breakfast cereals, and the like."
In fact, Ludwig headed a 1999 study, published in the Journal of the American Medical Association, finding that how much fiber was eaten was a better predictor of weight gain, insulin levels, and other heart disease factors in young adults than how much saturated or other fats were consumed.
Stand by Your Bran
High-fiber foods help control weight in several ways: They tend to fill you up faster, so you're less hungry and less likely to overeat. But they also tend to be lower in their glycemic index, producing less of a spike in blood sugar levels after meals and therefore less of an increase in insulin levels. High glycemic foods -- which include most refined foods and starches -- are associated with more weight gain and greater risk of diabetes.
"It's unclear whether it's the fiber itself, properties associated with fiber such as vitamins, minerals, and phytochemicals, or the fact that people who eat a high-fiber diet have much smaller swings in blood sugar," Ludwig tells WebMD. "But there's little doubt that eating more whole foods rich in fiber is optimal, for controlling weight and good health."
Most experts recommend getting at least 35 grams of fiber per day, but most Americans get about 12 grams -- largely because fiber is reduced or removed from foods that are refined, packaged or otherwise processed.
"If you look at people in Africa, Asia, and South America, they typically consume fiber in the 50-75-grams-per-day range, and it's quite easy to get that amount consuming a diet based on fruit, vegetables, legumes, and a moderate amount of animal products," Ludwig says. "But it's very hard to achieve that when you're eating highly refined, packaged foods."
SOURCES: Newby, P, American Journal of Clinical Nutrition; August 2004; vol 80; pp 504-513. Newby P, American Journal of Clinical Nutrition, June 2003; vol 77; pp 1417-1425. Ludwig, D, Journal of the American Medical Association, Oct. 27, 1999; vol 282; pp 1539-1546. Katherine Tucker, PhD, director, Epidemiology and Dietary Assessment Program; professor of environmental nutrition, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston. David Ludwig, MD, PhD, director, obesity program at Children's Hospital; associate professor of pediatrics, Harvard Medical School, Boston.
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High-Carb Diets May Help Maintain Weight
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