Foods high in sugar and refined carbohydrates such as bread, pasta and cereal increase the body's production of insulin. At high levels, insulin easily can cause food to be converted into body fat, according to Atkins' Web site.
"The name of the game is to reduce insulin levels," agrees Dr. Michael Eades, who co-authored the book "Protein Power" in 1996 with his wife, Dr. Mary Dan Eades. They opened Colorado Center for Metabolic Medicine in Boulder, Colo., in 1997.
People on the "Protein Power" plan initially reduce carbohydrate intake significantly. The plan promotes obtaining carbs from fruits and green, leafy vegetables instead of grains and starchy vegetables such as potatoes.
As its name suggests, the plan also calls for a higher consumption of protein, including fish, red meat, poultry and wild game. The amount of protein a person needs is determined by activity level, Eades says.
Eades says most people on the "Protein Power" diet don't have any restrictions on fat intake. He says fat and protein are more filling than carbohydrates and therefore people eat less and lose weight.
But diets that reduce carbohydrates and call for an increase in protein and fat consumption can increase cholesterol levels, says Carolyn Sagle, a registered dietitian at Jefferson Memorial Hospital in Ranson, W.Va.
In his 20 years in medicine, Eades says he has seen high-protein/low-carbohydrate diets have the opposite effect.
"It's the single-most effective thing I've seen for lowering cholesterol," he says.
Eades says about 15 percent of the cholesterol in the blood comes from food - the rest is produced by the body. Insulin stimulates cholesterol production, he says, so by cutting back on foods that promote the body's creation of insulin, cholesterol levels decline.
"The body prefers the breakdown products of carbohydrates," one of which is sugar, says Joyce Blakeman, a registered dietitian at Washington County Hospital. "Every cell wants sugar for energy."
Dr. Luis Balart, staff gastroenterologist at Memorial Medical Center in New Orleans and one of the authors of "Sugar Busters!" emphasizes the need to eat the most natural forms of carbohydrates.
He recommends substituting whole-grain rice for white rice and sweet potatoes for white potatoes to reduce sugar intake. He also suggests people avoid highly processed cereals and reach instead for bran cereals or oatmeal.
"The more back-to-nature you go ... the harder your body has to work to digest these things," says Balart, also chief of gastroenterology at Louisiana State University Medical School.
The slower foods are absorbed, the less appetite you'll have, he says.
Moderation is best
American Diabetes Association recommends a diet that contains 50 to 55 percent carbohydrates, 15 to 20 percent protein and 30 percent fat, Sagle says.
Many people get so caught up in the desire to reduce weight quickly that they don't consider the long-term effects of depriving their bodies of carbohydrates, Sagle says.
"We're so sick of being told low-fat, low-fat, that we're looking for something else," Sagle says.
People too often go to extremes in their eating habits rather than trying everything in moderation, Sagle says.
"We need to get more of a balance," Sagle says.
Sagle says those who eliminate carbohydrates from their diets risk deficiencies in vitamin C and calcium. They also may lose potassium, though it can be found in some lean meats, she says.
A lack of vitamin C can cause aching joints and bleeding gums. Such a deficiency also can make wounds heal more slowly and can weaken the body's ability to resist infection, Sagle says.
Eades says diets such as Protein Power that call for obtaining carbohydrates from the fruit and vegetable food groups provide plenty of essential vitamins.
-- What some of the diets recommend