DURHAM, N.C. -- A new diet study aimed at trying to reverse diabetes or diminishing its symptoms will allow participants to eat favorite high-fat foods like brownies and pizza by replacing the real fat with Olestra, a fat substitute now found only in snack foods like potato chips.
The study is being funded by Duke University Medical Center and the food is being provided by Procter & Gamble, manufacturers of Olestra.
The premise behind the study is that fat, not sugar or excess weight, is the primary culprit responsible for the exponential rise in type 2 diabetes among Americans, the Duke researchers say. More than 12 million Americans have type 2 diabetes, and 2,200 more people are diagnosed with the disease every day.
Using Olestra will enable the researchers to study a low-fat diet independently from a low-calorie diet, a proposition that had been nearly impossible before the development of Olestra. Subjects will eat the same number of calories they did before in order to prevent weight loss, but their fat intake will be reduced.
If the study confirms that fat is the primary trigger for diabetes in susceptible individuals, then patients would have a new treatment tool at their disposal. Instead of having to lose weight, they could reduce their fat intake by eating foods prepared with fat substitutes, which could be an easier proposition than cutting calories or total food intake, the researchers say.
"Weight loss is an effective way of managing diabetes, but it is extremely hard to achieve and even harder to maintain," said Dr. Richard Surwit, vice chairman of the department of psychiatry at Duke and co-investigator of the study. "Reducing fat without reducing calories or weight would prove much easier for the population at large, although we certainly do advocate that people maintain a healthy lifestyle that includes exercise and a nutritious diet."
Surwit maintains there is strong evidence that dietary fat is responsible for triggering a variety of diseases in genetically prone individuals. Diets like Pritikin and the Duke Rice Diet have shown that a low-fat diet can reverse heart disease, hypertension and diabetes, among other diseases, he said.
Surwit cites a 1998 Duke study of diabetes-prone mice in which feeding them a low-fat diet (10 percent fat) resulted in a reversal of their diabetes. The mice showed a drop in glucose and insulin levels -- primary indicators of diabetes -- before they lost weight, suggesting that fat reduction acts on insulin and glucose independent of weight loss.
"Science has clearly established that people and animals can develop diabetes before they become obese, so it stands to reason that people can begin to reverse their diabetes before they lose weight," said Dr. Mark Feinglos, professor of endocrinology at Duke and co-investigator of the study. "Weight loss and nutrition are certainly connected, but they are not inseparable."
As an example, Feinglos points toward the difference in how the body metabolizes fats and carbohydrates. He said that while a small candy bar (high in fat) and a bagel (high in carbohydrates) have the same number of calories, the body does not metabolize and store the two foods in the same way.
"All calories are not equal," Feinglos said. "Carbohydrates require burning of energy to convert to fat, whereas fat is converted directly to fat."
He said the current study is the first in humans to test the hypothesis that fat reduction alone can halt or slow diabetes progression. Until now, the medical community has relied on medication, weight loss and exercise to treat the disease. But statistics show that fewer than 5 percent of adults who lose weight are able to keep it off for five years, no matter what weight-loss method they use, and 62 percent of them regain all of their lost weight within five years.
By lowering dietary fat -- but not total calories -- in the typical American diet from 35 percent to 10 percent, the researchers hope they can mimic the results of their animal study, or at least produce a noticeable improvement in symptoms. While a 10 percent fat content is extraordinarily low, it can be accomplished using foods prepared with a fat substitute like Olestra, reputed to be tasty but having some unpleasant gastrointestinal side effects. Surwit said he will study the prevalance and severity of these side effects as well.
The Duke study will use specially prepared foods that contain Olestra instead of real fat.
Participants will eat all their meals at the Duke study site or take them to work or home. They will also keep a diary recording any foods consumed outside the diet. Weight checks and measures of glucose (blood sugar) and insulin levels will provide researchers with data on how the diet is affecting their diabetes.
"We expect to find that when participants are switched from a moderate-fat (35 percent) diet to a 10 percent fat diet, they will show a significant improvement in glucose metabolism," Surwit said.
Subjects interested in participating in the study must have type 2 diabetes but not currently be taking medication for their diabetes. For information, call (919) 684-3019.
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