Replacing other foods with a few daily servings of yogurt may help obese adults trim their waistlines better than calorie-cutting alone, a new study suggests.

Among 34 obese men and women who went on a 12-week, reduced-calorie diet, those who ate three daily servings of yogurt shed more fat around the middle compared with dieters who got little to no dairy and low amounts of calcium.

The findings add to recent evidence linking calcium and dairy foods to slimmer waistlines, including research showing that children and teens who get the recommended amounts of milk, yogurt and cheese tend to be leaner than their peers who shun dairy.

Though calcium is believed important for maintaining healthful levels of body fat, evidence is accumulating that dairy products may be particularly good weapons in the battle of the bulge, according to Dr. Michael B. Zemel of the University of Tennessee in Knoxville.

“Dairy contains a wide array of bioactive compounds,” said Zemel, who led the new research.

In the study, published in the International Journal of Obesity, Zemel and his colleagues had participants followed one of two diets for 12 weeks. One regimen slashed 500 calories from the dieters’ normal daily intake and allowed no more than one serving of dairy and 500 milligrams (mg) of calcium per day.

The other diet also cut out 500 calories, but included three daily servings of fat-free yogurt, which brought participants’ calcium intake to 1,100 mg - in line with the recommended intake for adults.

General Mills, maker of the Yoplait yogurt used in the diet, funded the research.

By the end of the study, both groups had lost weight and body fat, Zemel’s team found, but those in the yogurt group shed 61 percent more in fat pounds, as well as 81 percent more abdominal fat. They also held on to more lean, muscular body tissue compared with men and women in the low-calcium group.

Usually, Zemel said, when people lose weight through dieting, the tendency is to lose both fat and lean tissue.

It’s thought that calcium may keep body fat in check through effects on hormones that help regulate the storage of calories as fat and the breakdown of fat cells. Low calcium levels in the body, Zemel explained, may result in “bigger, fatter fat cells, and more of them.”

But some studies have suggested that dairy products, independent of their calcium content, help trim fat from the middle. The reason, according to Zemel, may rest in the fact that dairy foods have certain compounds, including a high concentration of small protein particles called branched-chain amino acids, whose metabolic effects may promote fat loss while preserving muscle.

However, he said, yogurt is no magic recipe for melting fat, and as the weight-loss mantra goes, “calories count.”

“There’s no monolithic answer to Obesity,” said Zemel, adding that a healthful overall diet and exercise are vital.

Also, yogurt is not unique among dairy products. This study focused on yogurt for “practical reasons,” Zemel said, because adults are likely to find several daily servings of yogurt more palatable than a few glasses of milk.

Still, while the study results are “impressive,” the mechanism by which calcium and dairy may promote fat loss remains a matter of speculation. according to an editorial published with the report.

And a chief question is whether the calcium must come in the form of dairy protein, writes Ruth B. Harris, an associate professor of food and nutrition at the University of Georgia in Athens.

It’s also unknown whether a cup of yogurt and a calcium supplement, for example, produce the same fat loss as three servings of yogurt, Harris notes.

“Identification of the factors that are important in promoting weight loss…is essential for the development of appropriate dietary recommendations,” she writes.

SOURCE: International Journal of Obesity, April 2005.