Recent headlines on the fitness wires trumpeting the benefits of yoga for weight control grabbed our attention: Could the calming discipline not just boost flexibility and build strength but melt calories, too? That would jolt us into an extended sun salutation -- if only it were so.

A published study did show that, on average, middle-aged people who practiced yoga controlled their weight better than those who did no yoga, but the findings come with some major caveats: First, the findings were based on self-reports of participants (a technique considered less reliable than data gathered by clinical observation). Second, the weight differences reported didn't reflect calories lost through yoga -- most yoga does not meet the American College of Sports Medicine's definition of moderate-intensity exercise, that is, exercise rigorous enough to burn substantial calories. Instead, researchers speculated, the weight drops may have stemmed from yoga practitioners' being more aware of their bodies, nutrition and fitness than non-practitioners.

The study of 15,500 people aged 53 to 57, which appears in the July/August issue of the journal Alternative Therapies in Health and Medicine, showed that the 102 participants of normal weight (with a body mass index, or BMI, under 25) who practiced yoga for four or more of the prior 10 years gained, on average, 3.1 fewer pounds (9.5 pounds vs. 12.6 pounds) during the period than did the other 7,000 normal-weight people who did no yoga at all.

Overweight participants who practiced yoga for four or more years -- only 30 people fit this description -- said they actually lost an average of five pounds over the 10 years, compared with an average gain of 13.5 pounds for the 7,500 or so overweight participants who did no yoga. Those who performed yoga for fewer than four years also fared better in weight control than did non-yogis, though their advantage was less. (Americans gain an average of one pound per year between ages 45 and 55.)

"We hypothesize that yoga's emphasis on developing body awareness and physical discipline supports the adoption of healthful dietary and exercise habits and thus indirectly affects weight control," the researchers wrote. That is, the deliberate micro-movements of yoga could give students a familiarity with -- and respect for -- their bodies that helps them avoid overeating and motivates them to pursue a physically active lifestyle.

It's also conceivable that the participants who did yoga are the type of people already more concerned about their bodies than the average person and that yoga is not a causative force in weight control, conceded researchers. In addition, this group of 15,500 is not thoroughly representative: It's a subset of a larger study's population, all from Washington state, who are more likely than most to use multivitamins and other dietary supplements.

Lead author Alan Kristal, associate head of the Cancer Prevention Program at the Fred Hutchinson Cancer Research Center in Seattle, readily acknowledged the study's limitations and said that a better-controlled study is needed to establish a strong link between yoga and weight control. But, he added, the survey results are promising.

"Techniques for weight loss are similar to [those for] smoking cessation," Kristal told us. "Not every method will work for everyone. This is just one more thing people could try if they are having trouble with their weight."

A more surefire weight control Rx: Get at least 30 minutes of moderate-intensity exercise at least five days a week, eat a healthy diet and get enough sleep.

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-- John Briley