Adding yoga practice to an existing weight loss regime (including commercial ones such as Jenny Craig or Weight Watchers) can increase its effectiveness according to Dr Alan Kristal, associate head of the Cancer Prevention Program in the Public Health Sciences Division at the Fred Hutchinson Cancer Research Centre.

Mindfulness, not exercise, is the key

Dr Kristal says that the mindfulness that results from regular yoga practice is responsible for this phenomena. He says that yoga as an exercise regime doesn't burn much in the way of kilojoules (Calories) and this is what prompted him, and his fellow researchers, to look for other reasons as to why their initial study found that regular yoga practice helped prevent middle-age spread in normal-weight people and appeared to promote weight loss in those who were overweight.

At the time, the researchers thought it probable that the weight-loss effect was likely due to increased body awareness, especially an awareness of hunger and satiety rather than the physical, calorie burning, activity of yoga practice.

Their follow-up study, published in the Journal of the American Dietetic Association in 2009, in which they used a "Mindful Eating Questionnaire" to survey more 300 people, confirms their theory. The questionnaire surveyed:

• disinhibition - eating even when full;
• awareness - being aware of how food looks, tastes and smells;
• external cues - eating in response to environmental cues, such as advertising;
• emotional response - eating in response to sadness or stress; and
• distraction - focusing on other things while eating.

The initial study had found that "men and women who were of normal weight at age 45 and regularly practiced yoga gained about 3 fewer pounds during that 10-year period than those who didn't practice yoga," Dr Kristal said. (Regular yoga practice was defined as at least 30 minutes once a week for four or more years.)

"This finding was independent of physical activity and dietary patterns. We hypothesized that mindfulness - a skill learned either directly or indirectly through yoga - could affect eating behavior," he said.

The new research found that people who ate mindfully - that is, those who were aware of why they were eating and who stopped eating when they were full - weighed less than those who ate mindlessly, who ate when they weren't hungry or used food as comfort in response to anxiety or depression. According to their article, "The researchers also found a strong association between yoga practice and mindful eating but found no association between other types of physical activity, such as walking or running, and mindful eating."

Dr Kristal, who is also a yoga enthusiast for the past 15 years, said that "These findings fit with our hypothesis that yoga increases mindfulness in eating and leads to less weight gain over time, independent of the physical activity aspect of yoga practice".

Why yoga works

"Yoga cultivates mindfulness in a number of ways, such as being able to hold a challenging physical pose by observing the discomfort in a non-judgmental way, with an accepting, calm mind and focus on the breath. This ability to be calm and observant during physical discomfort teaches how to maintain calm in other challenging situations, such as not eating more even when the food tastes good and not eating when you're not hungry," he said.

The bottom line

The take-home message of this research is simple, according to Dr Kristal: "Mindful eating is a skill that augments the usual approaches to weight loss, such as dieting, counting calories and limiting portion sizes. Adding yoga practice to a standard weight-loss program may make it more effective".