MIAMI -- There's no question low-carb diets can knock off the pounds, but there have been many questions and claims about the eating plan's long-term effects on heart health.

Now, new research is weighing in on that debate.

"It's the diet that defies conventional weight loss logic," Dr. Yvonne Braver, Women's Health Specialist from the Cleveland Clinic Internal Medicine said. "Low-carb plans often give the green light to generous portions of high-fat foods."

Advocates and some short-term studies suggest the diet may even help ward off heart disease, but the first long-term study finds the answer may be somewhere in the middle.

"The high-protein, high-fat diets are helpful for a lot of people," Braver said. "They do help a lot of people lose weight."

Harvard researchers said they analyzed 20 years of eating habits of more than 80,000 women and found no increase or decrease in the risk of heart disease among the low-carb eaters.

Researchers said they did find one exception -- women who chose fat and protein from vegetable sources had a 30 percent lower risk of heart disease.

They noted that the findings point to the importance of choosing healthy fats and complex carbohydrates when dieting.

Braver said she stresses to her patients that even with trendy diets, balance is still key.

"For people to find the best diet, they need to get on a sensible plan," Braver said. "Basically, eating normal food normally, incorporating lots of healthy fruits veggies and limiting portion sizes along with incorporating exercise into routine helps."

Researchers said the study is certainly not the final word on low-carb diets, but does add weight to the evidence that picking the right foods, even fats, can make a difference.

Short-term studies have suggested that low-carb diets may improve cholesterol and other risk factors for heart disease.

The study appeared in the Nov. 9, 2006, issue of The New England Journal of Medicine.