Low-Carb Diet Research and News

Diet doctors chew fat over obesity

DENVER (Oct. 23, 2000) -- Two of America's leading diet doctors faced off recently in a sometimes acrimonious debate over the best way to solve one of the nation's most vexing medical problems: the country's staggering rate of obesity.

But as Dr. Dean Ornish and Dr. Robert Atkins discussed such complex medical situations as glycemic control, insulin sensitivity and triglyceride levels, the key piece of advice -- albeit slightly bland -- came from Dr. Eileen Kennedy, a U.S. Department of Agriculture researcher: calories count.

"Any diet that restricts calories will result in weight loss" regardless of what foods are consumed, Kennedy told nutrition and diet experts attending the American Dietetic Association's annual meeting.

Ornish, an internist at the University of California, San Francisco, and author of "Eat More, Weigh Less," weighed in on the side of the government food guide pyramid, with its recommendation of a mostly plant-based diet rich in whole grains, low-fat dairy products and plenty of fruits and vegetables.

Atkins, a cardiologist and author of "Dr. Atkins' Diet Revolution," blames the USDA's carbohydrate-heavy pyramid for America's rise in obesity. He claims that Americans have gained staggering amounts of weight since the government encouraged people, through its pyramid, to eat low fat.

Fatter than ever
No one would argue that Americans are fatter than ever. Nearly 55 percent of U.S. adults are overweight and more than 22 percent are obese, according to the latest government statistics.

Between 1998 and 1999, obesity -- a leading cause of heart disease and diabetes -- rose 6 percent, Kennedy said.

The numbers may sound incredible, but this is no fuzzy math. On that, the two doctors agreed. Where they part ways is how best to trim the fat off of these figures.

"It's not a mystery. People are eating more fat, more calories and more sugar, and exercising less," Ornish said.

He argues that Americans consume too many animal products, the leading source of saturated fat in the diet. His mostly vegetarian reversal diet for those who have already been diagnosed with heart disease recommends no more than 10 percent of total calories from fat. Levels of fat are slightly higher for those who want to prevent heart disease or lose weight.

But restricting fat so much can be a tall order for a nation that has a hard time sticking to the government's recommendation of no more than 30 percent of total calories, of which no more than 10 percent should come from saturated fat, critics say.

Pyramid is erroneous
According to Atkins, Americans can no longer stomach such restrictions. In addition to being boring, they just don't work.

"Pushing the food pyramid is a major error," he said.

Instead, we should be substituting pasta, potatoes, bread and some starchy vegetables with beef, bacon, eggs and cheese. By restricting dietary carbohydrates, the body's preferred fuel source, the body is forced to use its fat stores for energy, he explained.

While Atkins concedes there are no long-term studies to support his claims ("But are there any diets that have been shown to have long-term success? I think not," he said), countless testimonials suggest that at least in the short-term, his plan seems to work.

He said he has found no evidence in the more than 40,000 patients he has treated that his diet is dangerous. He also cited a small study, which found that individuals on his diet lost weight, lowered cholesterol and triglycerides, another type of fat linked to heart disease, and raised levels of HDL ("good") cholesterol after four months.

But critics charge the diet is dangerously devoid of essential vitamins and minerals, raises a person's risk of heart disease and some forms of cancer, stresses the kidneys and causes the body to lose calcium. It is also said to cause constipation, headaches and bad breath.

The grain of truth
If there is a grain of truth to his claims, it is that eating simple carbohydrates -- white bread, pasta and bagels, for example -- seem to raise insulin levels, a risk factor for type 2 diabetes.

"There is some benefit in not eating simple carbohydrates," Ornish said. "The goal should be to eat more complex carbohydrates," which are high in fiber.

Studies have shown that fiber -- in short supply in the Atkins diet -- can improve the body's response to insulin. Protein and fat, Ornish noted, have been shown to raise insulin levels in the blood.

Another criticism is that restricting carbohydrate intake can lead to a sometimes dangerous medical condition known as ketosis, in which the body eats its own fat. While this may sound like dietary nirvana to some, it can change the blood's pH balance.

Atkins disputed the notion that the levels of ketones produced by his diet are dangerous. Ornish was not convinced.

"You can lose weight on chemotherapy but that doesn't mean it's a good way to do it," Ornish said.

Kennedy provided statistics from a government study of about 5,000 Americans who stuck to the food guide pyramid. About 20 percent to 30 percent of their calories came from fat; about 55 percent from carbohydrates; and 15 percent from protein.

Both men and women who followed the government's advice had a lower body mass index -- a measurement of a person's weight in relation to their height -- than people on a low-carbohydrate diet.

"Unequivocally, I can say the reason Americans are getting fatter is that they are not following the advice of the USDA," Kennedy said.

"The evidence is clear: long-term weight loss is slow and steady, with a dietary pattern that can be sustained over a long period of time," she added.