Diabetes Forecast

A Healthier Way to Lose Weight

A Diabetes Expert Shows That Not All Diets Are Created Equal

Researcher: Rodica Pop-Busui, MD, PhD
Occupation: Assistant Professor in the Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, and codirector of the Michigan Neuropathy Center, University of Michigan
Focus: Endocrinology
Research Funding: ADA Clinical/Translational Research Award

It's practically a given that people with diabetes who are overweight need to reduce pounds. But it turns out that weight loss alone may not automatically lead to better health—at least not when it comes to the heart.

Rodica Pop-Busui, MD, PhD, is an expert on the complications of diabetes, especially the changes the disease causes in the way the heart works. With a grant from ADA, she's looking at the impact of diet and exercise on the nerves that help keep the heart beating smoothly. "I want to know why patients with diabetes have much higher levels of cardiac complications," says Pop-Busui, an assistant professor of internal medicine at the University of Michigan.

The answer lies deep in the heart's control system, a set of nerves and chemical pathways that keep things ticking involuntarily, without any conscious thought. Pop-Busui's research has shown that these nerves often don't work as well in people with something called metabolic syndrome. "Metabolic syndrome is considered a pre-diabetic state," she says. It's essentially several risk factors that are clustered together: obesity, high blood pressure, and insulin resistance. In a healthy heart, a complex, precisely balanced set of chemical reactions keeps the nerves working smoothly. When the balance is thrown off, the chances of developing arrythmia, or irregular heart rhythm, rise.

Pop-Busui set up an experiment to see if a dramatic change in diet and exercise habits can have an equally dramatic effect on heart health. She started with 25 volunteers, all of whom have metabolic syndrome. Over the course of six months, the volunteers went through a rigorous diet and exercise program while being monitored for changes to the chemistry of their heart nerves. Their results are being compared with those of a healthy, non-obese group that didn't change its diet or take part in any special exercise program. The experiment involved both a program of cardiovascular exercise and a complete change in what participants ate. "We want to see the effect of intervention beyond weight loss," Pop-Busui says. "It's not just losing weight, but losing weight on a specific diet that helps cardiac function."

The diet Pop-Busui chose is based on a phenomenon that doctors first noticed in the 1940s. In many parts of the Mediterranean—Greece and Italy, for example—traditional meals include lots of fat. But when researchers looked at mortality rates in the 1960s, they found that people in the region had much lower rates of heart disease than their counterparts in America, and tended to live much longer. In 1995, a prominent paper in the American Journal of Clinical Nutrition by Harvard University School of Public Health epidemiologist Walter Willett suggested that the prominence of unprocessed vegetables, legumes, and fish—rather than red meat and white bread—in the region's cuisine constituted a "Mediterranean diet." Credit was also given to the widespread use of olive oil rather than animal fats in Greek and Italian cooking. Willett suggested the diet might be a model, "attractive for its famous palatability as well as for its health benefits."

But for people accustomed to eating American-style, a diet based on rural Greek farm food circa 1960 was a hard sell. Think no red meat, no butter, no margarine, and no cream. "The diet requires a lot of work," says Pop-Busui. "A lot of the patients couldn't even understand what it was, it's so different from what they've been eating before." Study participants had to cut out commercial candies and pastries in favor of fruit (three or more servings a day) and replace white bread and rice with whole-grain bread, whole-grain pasta, and beans. To help them make sense of the diet's demands, the researchers provided sample menus and carefully monitored their food intake and how they prepared meals—tracking each food item eaten using a points system. "I had many patients tell me, 'I didn't realize I'd like fish so much,' " Pop-Busui says. (Red wine is an integral part of the program, which eases the pain a bit.)

Pop-Busui's theory is that the diet's benefits might extend to people at risk for diabetes. She wanted to see if the diet and exercise program could alter the way the heart's nerves work, halting or reversing the changes caused by metabolic syndrome. To spot shifts in the heart's mechanics, Pop-Busui used chemical tracers and special scans to see how the heart's nerves were working. As the study progressed, she also tracked participants' weight, waist size, and muscle mass. Exercise can convert fat to denser, heavier muscle, keeping weight the same but improving cardiac function and overall health. "They're not necessarily losing that much weight, but they're completely changing their body composition," Pop-Busui says. In that sense, she says, "the changes are spectacular. So far we are very encouraged by what we are seeing." If this research pans turns out as she expects, it could mean yet another crucial tool for managing type 2 diabetes.

To sponsor an ADA research project at the Research Foundation's Pinnacle Society level of $50,000 or more, call Elly Brtva, MPH, managing director of Individual Giving, at (703) 253-4377, or e-mail her at ebrtva@diabetes.org.



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