The Low-Carb Lowdown
Should you consider the latest diet trend?
By Julie Rothschild Levi
Photos by Cliff Grassmick
These days, it’s more common to hear “hold the bun” than “hold the pickles, onions, and lettuce.” People are embracing low-carbohydrate diet plans in droves, stocking their kitchens with protein-rich foods and low-carb goodies—all with the hopes of shedding excess pounds, stabilizing blood sugar, and improving metabolic and cardiac health. There hasn’t been a diet trend like this since the advent of low-fat eating nearly 20 years ago. With 65 percent of the American adult population overweight or obese, it’s no wonder folks are seeking weight loss solutions.
But is reducing intake of grains, beans, and certain vegetables and fruits—all high in carbs—and loading up on meat and fats really a healthy idea? That depends on whom you talk to. Despite promising evidence that a low-carb diet can help you lose pounds quickly, many experts express reservations about the lasting safety of many low-carb plans because the longest low-carb study to date followed dieters for just one year.
Viewpoints could change, however, with the outcome of a large, five-year study sponsored by the National Institutes of Health that will compare the long-term health effects of low-carb, high-protein diets, such as Atkins, to conventional diets based on the now oft-disputed U.S. Department of Agriculture’s Food Guide Pyramid. But until that study is completed and the results released, many of us are left wondering what to eat—and which nutrition gurus, health experts, and dieters to heed. Here’s a look at the pros and cons of both perspectives to help you make your own decision.
The good-carb camp
Before you hop on the low-carb bandwagon, you should first know exactly what carbs are, what they do for your body, and why some experts think they are important for your health. Carbohydrates, which include the sugars, starches, and fiber abundant in the plant world, “provide the main source of energy for our bodies,” says Cathy Fitzgerald, MA, RD, a University of Michigan Health System nutrition specialist. Although the low-carb trend has many believing that all carbohydrates are bad, the unprocessed or unrefined “complex” carbs found in most fruits, vegetables, legumes, and whole grains are healthy, says Fitzgerald. They’re rich in the vitamins, minerals, fiber, and phytochemicals that help fight disease.
On the other hand, “simple” carbohydrates—the sugars that are added to food products—abound in refined breads, pasta, baked goods, juices, milk, and candies. These additives are virtually void of fiber and beneficial nutrients. Foods with a high sugar content and no fiber get digested quickly and rapidly convert into glucose, which jacks up blood sugar. This forces the pancreas to produce excess insulin to help the body process all the glucose. Subsequently, blood sugar takes a nosedive, sending a “hungry” signal to the brain, triggering people to eat readily available foods to restore their blood sugar quickly. Insulin also prevents the breakdown of stored fats, so the more your insulin levels go up, the more fat you eventually accumulate and the greater your risk for obesity, diabetes, and heart disease. Reducing or eliminating sugar from the diet is a step toward fixing the elevated blood sugar problem. But, says Fitzgerald, “it’s important we don’t cut [carbs] out of our diet” altogether.
John McDougall, MD, founder and medical director of the McDougall Wellness Center in Santa Rosa, California, and author of numerous health books including The McDougall Program for Maximum Weight Loss (Plume, 1995), agrees. He notes that most people run into trouble not by eating carbs, but by eating the wrong kinds of carbs. “The carbohydrates Americans eat are sugar and white flour,” he says. If you look at the healthiest, trimmest people in the world, says McDougall, their native diets are rich in carbs from rice, corn, millet, or potatoes. Their weight and health problems arise only after they move to the United States and decrease their intake of carbs, he says, while increasing their intake of protein and fat. McDougall’s own diet plan is high in carbs (70 percent to 80 percent of daily calories) and very low in fat and moderate in protein (approximately 10 percent of daily calories each).
Current government dietary guidelines recommend that 45 percent to 65 percent of daily calories come from carbohydrates (an updated USDA pyramid is slated for release in 2005); 130 grams of carbs should be the minimum daily dose, says Fitzgerald. Eat fewer than that, and there are implications for proper cognitive function. “Carbohydrate is the preferred fuel of the brain,” says McDougall. When there aren’t any carbohydrates in the system to burn, the brain will, in desperate circumstances, burn fat. Burning fat, McDougall explains, decreases circulation and drops the blood’s oxygen content by about 20 percent, impairing the nervous system. Not surprisingly, some low-carb dieters do experience sluggishness and “brain fog.”
The low-carb viewpoint
Low-carb supporters have a beef with the carbs-are-essential argument. “You really don’t need any carbohydrates at all,” says Michael R. Eades, MD, who practices nutritional and metabolic medicine and is coauthor of Protein Power Lifeplan (Warner Books, 2000). “You could live the rest of your life without eating another single carb and do just fine.” There are no carbohydrate-deficiency diseases, he points out, whereas protein-deficiency diseases do exist.
But if we don’t take in enough carbs, how can our bodies function properly? A healthy liver converts protein into glucose through a metabolic process called gluconeogenesis, says Eades. Not only does your body get the sugar it needs this way, say low-carb proponents, the process also eats up energy, allowing you to burn fat and lose weight.
Despite the weight loss boon, Eades acknowledges that a protein-only diet would be a “boring” one, and would lack many phytonutrients and fiber from plant foods. Therefore, low-carb diet plans—from Atkins to South Beach—allow for minimal amounts of carbohydrates in the diet, anywhere from 20 grams to 40 grams daily, during the initial weight loss phase. These carbs come mostly from nutrient-dense, fiber-rich fruits and vegetables, such as leafy greens and berries.
Carbs can have a bigger place in these diets—up to 120 grams daily, depending on the plan—once you near your goal weight. This means you can enjoy a greater variety of fruits and vegetables (even a small potato, shunned at first because of its high carb count), a slice of bread, or a half-cup of rice at mealtime.
But what about all the fat that accompanies a high-protein diet? After all, the American Heart Association (AHA) advises keeping calories from fat under 30 percent for optimal health. On a low-carb diet, fats constitute up to 50 percent of calories, albeit mainly from unsaturated plant fats (found in olive oil and avocados), omega-3 essential fatty acids (found in fish and walnuts), and some saturated animal fats.
“The only fats that are really harmful are trans fats, such as partially hydrogenated oils” found in margarine and processed foods, says Gil Wilshire, MD, president of the Carbohydrate Awareness Council, a low-carb advocacy group in Falls Church, Virginia. “I don’t see any data that animal fats by themselves are harmful.”
For decades, however, doctors have told us that eating too much saturated fat can lead to obesity and heart disease. In 1998, the AHA even stated that “there is overwhelming evidence that reductions in saturated fat, dietary cholesterol, and weight offer the most effective dietary strategies for reducing total cholesterol, LDL-C levels, and cardiovascular risk” (Circulation, 1998, vol. 98). And researchers recently found that significant premenopausal intake of saturated fat—mainly red meat and high-fat dairy foods—may be associated with an increased risk of breast cancer (Journal of the National Cancer Institute, 2003, vol. 95, no. 14).
Yet other recent studies, such as one in the New England Journal of Medicine (2003, vol. 348, no. 21), indicate that a low-carb, high-fat diet actually increases levels of “good” (HDL) cholesterol and decreases triglycerides (harmful fats in the blood), important factors in preventing heart disease. And any weight loss usually helps “bad” (LDL) cholesterol levels fall. So the low-carb debate continues.
A 2003 study showed that those on very low-carb diets lost twice as much weight as those on low-fat diets. Losing weight on low carbs
Of course, the number-one reason low-carb, high-protein diets are gaining so many followers is the simple fact that adherents are losing weight, and lots of it. A 2003 study in the Journal of Clinical Endocrinology and Metabolism (vol. 88, no. 4) showed that those on very low-carb diets lost twice as much weight as those on low-fat diets. And a study conducted by the Harvard School of Public Health, presented at last year’s annual meeting of the North American Association for the Study of Obesity, found that low-carb dieters who consumed 300 calories more than those on standard low-fat diets still lost more weight.
Aside from improving blood-lipid levels and weight loss, it’s the stabilization of insulin levels, proponents say, that makes low-carb diets especially beneficial for those with prediabetic conditions, as well as those with type 2 diabetes, high cholesterol, high blood pressure, and gastroesophageal reflux disorder.
Both Eades and Douglas Markham, DC, author of Beyond Atkins (Total Health Care Partners, 2004), say they’ve had success helping hundreds of patients reduce or get off cholesterol-lowering, blood-pressure, and diabetic medications. A recent study showed that a high-protein, low-carb diet improved insulin sensitivity in severely obese individuals more so than a calorie- and fat-restricted diet and resulted in greater weight loss (New England Journal of Medicine, 2003, vol. 348, no. 21). Still, eating low carb isn’t a foolproof way to lose weight, usually because dieters overeat protein and fat or become bored with their menu and veer off their plan.
The magic formula
What’s undisputed among nutritionists is that low-carb diets are weaning people off unhealthy carbohydrates and turning them back to healthful oils, nuts, seeds, and fiber-rich fruits and vegetables. Many of the new low-carb plans steer away from the steak, bacon, and butter-drenched meals some low-carb diet plans advocate, instead highlighting leaner cuts of meat, low-fat cheeses, fish, and poultry as healthy protein options. They also recommend that any grain foods you eat come from whole-grain sources.
In the end, many experts say the secret to getting and staying trim is decreasing your caloric intake while increasing the calories you burn each day through exercise. According to Fitzgerald, the country has a weight problem because processed foods have become convenient and inexpensive (pretzels and cookies are less expensive than nuts and apples). And, most important, people have lost sight of portion control. On the Food Guide Pyramid, for example, one serving size is a half-cup for pasta or rice. “Many eat much more than that,” she says.
So it seems the real magic formula is to eat less and exercise more. It’s not glamorous. It’s not a fad. Some may prefer to achieve this formula while on a low-carb, high-protein diet. Others will continue to enjoy their pasta. Either way, it’s important to pay attention to the diet plan that feels right for your body, your lifestyle, and your health goals.
Julie Rothschild Levi’s perfect meal contains protein, complex carbs from vegetables, and simple carbs from dark chocolate.