Exercise can reduce the amount of fat stored in muscle and around the organs better than cutting calories, say new findings out of St. Louis University.
The study also found that reducing calories can cut some risk factors for diabetes and heart disease with an effectiveness equal to exercise.
"We learned that exercise and calorie reduction have health benefits independent of one another," said Edward Weiss, assistant professor in the department of nutrition and dietetics at St. Louis University.
"You need a healthy, low-calorie diet and exercise to get the most out of your health," Weiss said. "Don't be fooled if you're a healthy weight and only doing one of the approaches."
The findings are part of a series of studies he has led for years. In those studies, researchers unexpectedly found that connection between cutting calories and a reduced risk factor for diabetes and heart disease, Weiss said.
"We expected calorie restriction to work well but not as well as exercise-induced weight loss," he said. "We thought we'd see a greater improvement in diabetes risk for exercisers, but we didn't see that.
"We don't know why yet, but we think it might have something to do with changes in the intestines."
That sparked the "Calorie Restriction, Exercise and Glucoregulation in Humans," or CREG, study which began late last year and is expected to last another year or more, Weiss said.
The finding that exercise in some cases had double the effect of calorie reduction was somewhat of a surprise. Most weight loss experts say calorie reduction is the only effective way to lose fat.
"Calorie restriction promotes weight loss but in some cases, exercise alone can reduce weight," said Kathy Kress, associate professor in the nutrition and dietetics department and one of the researchers.
Excess body fat is blamed for a myriad of conditions, most of them bad. Controlling fat is the target for scores of researchers.
In Weiss' studies, the fats under scrutiny are:
• Intermuscular fat that's deposited between muscle fibers. "That would be like the marbling in a steak," Weiss said. The form being studied makes up about 10 percent of the total body fat.
• Visceral fat packed around organs and behind muscles, makes up about 10 percent of a person's body fat.
• Subcutaneous fat, the "love-handle" fat just below the skin and above the muscles is about 50 percent of body fat. "That's the fat you can pinch," Weiss said. It's less of a health threat except for causing joint problems among people who are obese, Weiss said.
Liver fat, the most dangerous place to accumulate fat, isn't part of the study.
The remaining body fat is in other places doing other things, for example, components of nerve tissue, Weiss said.
In the CREG study, 45 people have been divided into three groups: Some work on losing weight with exercise only; some by eating less and some by doing both.
The test subjects are "reasonably healthy" people who are free of diabetes and cardiovascular problems, ages 45 to 65, and no one has a body mass index over 30 — the line between being overweight and obese.
Kress helped dieters plan meals and make healthy choices. "If that didn't work, we sent food home with them," she said.
Exercisers used gym machines for 60 to 90 minutes six to seven days a week, then added more walking steps to their daily routines, Weiss said.
"The misconception is that if you do 20 or 30 minutes of exercise (a day), you can lose weight. That amount of exercise is not going to add up to weight loss," Kress said. "Weight loss is work and it takes effort."
Over one year, exercisers lost six to 10 pounds of fat, Weiss said, more of it the troublesome fat. The reduction in subcutaneous fat was on average identical among exercisers and dieters.
Those who have exercised and dieted have done better than either of the other groups, Weiss said.
The final data should be available in about two years, Weiss said.
Dr. Samuel Klein, a professor of medicine at Washington University School of Medicine and head of the school's Weight Management Program, strongly advocates calorie reduction as the front line of weight loss.
The study doesn't change that, he said. Instead "It shows an additional beneficial effect of exercise on body composition during diet-induced weight loss," he said.
Those who exercised lost more body fat "... in areas that are associated with metabolic abnormalities," he said.
That doesn't change that "Exercise is a very difficult way to lose weight," Klein said.
"So if you run for a mile and come home and eat a slice of pizza and a beer, everything you've done has been (negated)," he said. "And in some people, increased exercise stimulates appetite and in some people it reduces appetite."
The studies have been funded by grants from federal and private sources.