Cut carbs to lose weight?

It may not be that simple.

So, now the latest study has arrived, showing that Americans have eaten steadily more carbohydrates as their waistlines have expanded.

Already, low-carb advocates are pointing to the news as proof of their argument: that carbs, not fat, are the villains packing on the pounds.

"I'm very glad this has actually come out," said Dr. Robert Campbell, assistant professor at the University of South Florida, a family practitioner who specializes in treating obese patients. "I've been touting low-carbs for seven years, and now the data is starting to show it."

Don't pass the bacon yet, other scientists say. They point to the same data from the federal Centers for Disease Control and Prevention to show the real problem simply is that as a nation, we're eating more. More carbs, yes. But also more fat. And more is fatter.

"We eat too much," said registered dietitian Elaine Turner, an associate nutrition professor at the University of Florida. "That's really the main finding, that we are continuing to increase our calorie intake. And when you do that, you're going to gain weight unless you increase your energy expenditure."

Both sides find some points of agreement. Calories matter. So does exercise. And not all carbs are the same: Cookies are not cauliflower.

"I don't think it's either-or," said Gary Foster, clinical director of the Weight and Eating Disorders Program at the University of Pennsylvania School of Medicine. "It's probably both. These data suggest pretty strongly that carbs are the major culprit in increasing calories. ... One way to decrease calories is decrease carbs."

The most recent data, reported Friday by the CDC, show that over the past 30 years, the calories Americans eat have markedly increased - by 22 percent for women and 7 percent for men from 1971 to 2000. Most of that increase has come from carbohydrates.

Those findings only add fuel to the fat vs. carb debate. Low-carb advocates have been buoyed by studies showing that low-carb, high-protein diets cause people to lose more weight than groups on the traditionally recommended low-fat diet.

Still, many of the studies are small, and some of them are contradictory. For example, Foster recently conducted a study that showed low-carb dieters lost more weight at first, but regained it just as fast as other groups. Larger studies are under way, and for most scientists, the debate is far from settled.

"I'm not promoting that diet at this point, because we just don't have enough data yet," Foster said. "But I do think it's surprising. It might give overweight people a viable alternative. We have to nail down whether it's safe in the long term."

Try explaining that to the folks already inspecting food labels for "net carbs" and buying low-carb beer. A generation ago, many Americans responded to low-fat diet advice by buying fat-free cookies - low in fat, but high in calories.

"When we saw the words "fat-free' on the label, we forgot there were calories," said Nadine Pazder, a registered dietitian at Morton Plant Hospital in Clearwater. "We developed a kind of fat-free amnesia there."

Now, many nutrition experts worry people will do the same with carbs.

"I went to the store recently and looked at these new low-carb products, and they're not any lower in calories," said James Hill, director of the Center for Human Nutrition at the University of Colorado Health Sciences Center and a past president of the North American Association for the Study of Obesity. "We've got to get over the idea that if we stop eating fat, or carbs, or protein, everything is going to be okay. It's about total calories."

But for advocates, carbs play a role in gaining weight, and low-carb diets make losing weight easier. The Atkins theory: that carbs, especially simple carbs such as white bread or cookies, make people hungrier because they increase blood sugar rapidly, releasing a flood of insulin into the bloodstream. The surge of insulin sweeps sugar away so fast that blood sugar drops too low - resulting in cravings for more carbs.

"Once we became industrialized, we increased the amount of processed and refined sugars," Campbell said. "We've got to rethink our strategy."

Campbell said he has seen many of his patients lose weight on low-carb diets, and he is now working on a study comparing low-carb diets to others. But even Campbell said he always offers patients different options, and he's reluctant to recommend high-protein, low-carb diets to patients with certain health problems, such as kidney disease.

The CDC's study isn't perfect. Jacqueline Wright, epidemiologist with the CDC's National Center for Health Statistics and lead author for the report, pointed out that the data came from asking people to report what they had eaten in the past 24 hours. People tend to forget some of what they ate, she said.

Still, she said, the study's bottom line, that people are eating more, should be accurate.

"We may be underestimating with the method we're using, but we were underestimating with the same method in 1971," she said.

For Turner, more information is needed.

"I don't think we've come to a science basis for saying there's something about carbs that make us fat, or fat that makes us fat," she said. "It's about balance."

But, she says, that's just not appealing.

"It's not a flashy message: Eat in moderation and exercise," Turner said. "It sounds hard. And when something sounds hard, we continue to look for something that will be easy."

- Lisa Greene covers medicine. She can be reached at greene@sptimes.com

Nutritionists say "good" carbs are complex carbohydrates that are digested more slowly and have more nutrients and fiber. "Bad" carbs are refined and processed foods that are digested quickly and contain less fiber and more sugar.

Oatmeal

Broccoli

Whole grain bread

Spinach

Pears

Strawberries

Doughnuts

Cookies

White bread

Croissants

Potato chips

Soda

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