No ‘One Size Fits All’ Weight Loss Diet continued...
"What is newsworthy about this study is it offers a biological explanation for the observation that different people respond differently to the same diet," Fernstrom tells WebMD. "There is a subgroup of people who squirt out a lot of insulin in an exaggerated response to sugary foods -- and maybe these are people who respond much better to a low-glycemic-load diet."
Low-glycemic-load diets are often called "slow-carb" diets. The idea of these diets is to avoid starchy and/or sugary carbohydrates -- such as white potatoes or white rice -- and to eat lots of fruits, nonstarchy vegetables, legumes, and whole grains.
It's an offshoot of high-fiber diets that cut cholesterol and heart disease risk, says David J.A. Jenkins, MD, PhD, DSc, director of the clinical nutrition and risk factor modification center at St. Michael's Hospital, Toronto, and professor of nutritional sciences at the University of Toronto.
"Many of the things we use in our high-fiber diet -- such as barley, oats, and psyllium -- have significantly lower glycemic indices than their low-fiber counterparts," Jenkins tells WebMD. "The sticky parts of fiber keep your blood sugar down and your cholesterol down. Two birds are hit with one stone."
Studies of the low-glycemic-load diet get mixed results. The new study offers an explanation, says Stephen Cook, MD, assistant professor of pediatrics at the University of Rochester, N.Y. And the findings may explain why a diet that works at one stage of life does not work later in life.
"We know insulin sensitivity changes over time," Cook tells WebMD. "People in their 20s and 30s are much more sensitive than older people. So in looking at this data, I think it is important to keep in mind the fact that adults go through different developmental stages, just as children do."
Cook says there's still no good clinical test for insulin secretion. But Fernstrom suggests that the current three-hour glucose challenge test could be adapted to a 30-minute version acceptable to most patients.
"If the prediction made in this study holds out with further study, this could be a very useful tool," Fernstrom says. "This study shows that everybody who is fat does not have problems with glucose and insulin, but some do. So maybe we can identify a subgroup of people where we can say, 'This kind of diet could work really well for you.'"