Carb control [the smart way]: take the very best of the reduced-carb diets and lose the rest—including extra pounds

Shape, June, 2004 by Katherine Tallmadge

As a registered dietitian, I've come to realize that I'm more likely to win the lottery, fly to the moon or write tragedies that surpass Shakespeare's than talk someone out of going on a low-carb diet. Everywhere I go, the low-carb craze is all anyone is talking about, and it shows no signs of abating. In fact, 26 million Americans--about 12 percent--have put carbohydrates on their enemies list, according to a recent poll by Opinion Dynamics Corp., a market-research firm based in Cambridge, Mass.

Why we've got low-carb fever

The appeal is easy to see: Low-carb weight-loss plans like Atkins, the Zone and the South Beach Diet offer two things nearly everyone wants in a diet: First, these programs are easy to understand and follow--no measuring portion sizes, counting calories or consulting charts. Even better, you can eat foods that many of us love, such as burgers, bacon and cheese. The theory behind low-carb regimens is easy to wrap your head around too: If you take in too many carbs, which makes blood sugar (glucose) peak, you spur insulin production, which then causes blood sugar to abruptly dive. This increases appetite, which in turn causes you to eat more and gain weight. So it's a (seemingly) simple equation: Cut your carbs and you shed pounds.

The most important reason for the diets' appeal, however, is the most obvious: You see results quickly. Not surprising when you consider one very basic truth: Calories matter. "If 55 percent of your calories are from carbohydrates and you cut those carbs out, you're cutting a lot of calories," says Joanne Slavin, Ph.D., R.D. a carbohydrate researcher and professor in the department of food science and nutrition at the University of Minnesota in St. Paul. "You will lose weight."

No (carb-) free lunch

But as strong as the appeal of these low-carb diets is, it's far from the whole story when it comes to health--and weight loss. Cut carbohydrates down to the very, very low amounts recommended by diets like Atkins--which advises just 20 grams of a certain type of carb in its minimum two-week induction period--and you'll put yourself at risk for a host of troubles. Perhaps most worrisome is how the brain is affected when the body doesn't get enough carbohydrate: In one study at the University of Pittsburgh School of Medicine, 21 overweight women were placed on a very low-calorie diet for 28 days. Eleven women in the group ate just 10 grams of carbs a day, while the rest were fed meals with a balance of protein, carbs and fat. Weight loss was comparable for both groups, but those on the carb-restricted diet had difficulty completing a task that required higher-order cognitive function.

In another study, of 600 subjects at the Massachusetts Institute of Technology (MIT) in Cambridge, researcher Judith Wurtman, Ph.D., director of the Program in Women's Health at the MIT Clinical Research Center, found that low carb equals lowered serotonin levels too. Reduced amounts of this mood-regulating, feel-good neurochemical may help explain the grumpiness and fatigue some low-carb dieters experience--a side effect that may strike women more acutely, as they produce less serotonin than do men.

The physiological process that impairs your brain (and body) when you go very low carb is called ketosis--the breakdown of fats in the body as a result of a carbohydrate deficiency. While it does work to suppress appetite, ketosis also causes the excretion of calcium and potassium in the urine and may harm the bones and kidneys if carb deprivation is unchecked.

Still not convinced? Then consider the results of a six-month study at Duke University funded by the Atkins Center for Complementary Medicine (the same folks behind the Atkins diet): The study found that while subjects did lose weight, 68 percent of them experienced constipation, 63 percent had bad breath, 51 percent reported headaches, and 10 percent noted hair loss.

Is the weight loss worth it? Probably not. When researchers at three universities (the University of Pennsylvania School of Medicine in Philadelphia was the lead center) compared a low-carb, high-fat, high-protein diet (with no restriction given on number of calories) to a high-carb, low-calorie (1,200-1,500 calories for women), lowfat diet, they found that while the Atkins-diet group lost about 4 percent more weight in the first six months, by one year weight loss was comparable for both groups. In the end, a low-carb diet is as difficult to adhere to as any--and may actually be harder to stick with, since the choice of foods is more restricted and there are more side effects than with a lowfat, calorie-controlled diet.

A saner, healthier approach

"Fortunately, you can follow a lower-carb diet that's nutritionally sound and healthy," says Jo Ann Hattner, M.P.H., R.D., author of Help! My Underwear Is Shrinking! (American Diabetes Association, 2003). This is especially good news if you are someone who is able to lose weight more easily by eating fewer carbs. (That likely includes many of us: A recent report from the Centers for Disease Control and Prevention found that American women are consuming far more calories than they did 30 years ago--335 more a day, on average!--and there's reason to believe much of that is coming from refined carbohydrates such as those found in pizza, salty snacks and restaurant foods.) So it seems many of us could benefit from a (sane) reduction in carbs. Here, then, are the four essential things you need to remember when following a healthy lower-carb diet for weight loss.