Too Much Fructose Could Leave Dieters Sugar Shocked
Dieters should focus on limiting the amount of fructose they eat instead of cutting out starchy foods such as bread, rice and potatoes, report the researchers, who propose using new dietary guidelines based on fructose to gauge how healthy foods are.
"There's a fair amount of evidence that starch-based foods don't cause weight gain like sugar-based foods and don't cause the metabolic syndrome like sugar-based foods," said Dr. Richard Johnson, the senior author of the report, which reviewed several recent studies on fructose and obesity. "Potatoes, pasta, rice may be relatively safe compared to table sugar. A fructose index may be a better way to assess the risk of carbohydrates related to obesity."
Many diets -- including the low-carb variety -- are based on the glycemic index, which measures how foods affect blood glucose levels. Because starches convert to glucose in the body, these diets tend to limit foods such as rice and potatoes.
While table sugar is composed of both glucose and fructose, fructose seems to be the more dangerous part of the equation, UF researchers say. Eating too much fructose causes uric acid levels to spike, which can block the ability of insulin to regulate how body cells use and store sugar and other nutrients for energy, leading to obesity, metabolic syndrome and type 2 diabetes, said Johnson, the division chief of nephrology and the J. Robert Cade professor of nephrology in the UF College of Medicine. UF researchers first detailed the role of uric acid on insulin resistance and obesity in a 2005 study in rats.
"Certainly we don't think fructose is the only cause of the obesity epidemic," Johnson said. "Too many calories, too much junk food and too much high-fat food are also part of the problem. But we think that fructose may have the unique ability to induce insulin resistance and features of the metabolic syndrome that other foods don't do so easily."