Though health-conscious eaters often shun whole milk, a new study suggests that adults who favor full-fat dairy gain less weight over time.

Swedish researchers found that among more than 19,000 middle-aged women, those who had at least one serving of whole milk or cheese each day put on less weight over the next 9 years than women who consumed these foods less often.

The potential role of dairy foods in weight control won much attention after some recent studies suggested that milk, yogurt and other dairy foods might help regulate body fat. However, the picture is far from clear, as other research has failed to find that dairy products benefit the waistline.

The new findings, published in the American Journal of Clinical Nutrition, are unlikely to clear up the confusion.

For one thing, only whole milk, and not low-fat milk, seemed to offer protection against weight gain. For another, the benefit was seen only among women who were normal-weight at the start of the study.

It's always possible that the associations between dairy intake and weight gain do not reflect a direct action of dairy foods at all, according to Doctor Magdalena Rosell, a researcher at the Karolinska Institute in Stockholm and the study's lead author.

Eating habits can be seen as a marker of overall lifestyle, and women who favored whole milk might have had other habits that aided their weight control, Rosell said.

It's also possible that women who had already been gaining weight opted to drink low-fat milk making the milk a "marker," but not a cause, of weight gain, according to Rosell.

The findings are based on data from 19,352 women ages 40 to 55 who were surveyed about their diets, weight and other health factors at the study's outset and again 9 years later.

Women who said they had whole milk or cheese at least once a day throughout the study period were less likely to report a significant weight gain defined as 1 kilogram or more per year.

One theory on why dairy products have been linked to lower body weight is that the calcium aids in fat regulation, but a number of studies have refuted that notion. The new findings cast further doubt, since low-fat milk showed no positive weight effects.

It's possible, according to Rosell, that a type of fat found in dairy foods called conjugated linoleic acid, or CLA, aids in weight control.

However, she added, there's not enough evidence yet to support that idea. At this point, there's no reason, Rosell said, for people to eschew the general advice to choose low-fat dairy products, which are lower in artery-clogging saturated fats.

"From what we know today, I do not see any reasons to change that recommendation," she said.

(China Daily January 8, 2007)