COLUMBUS, Ohio - If dieting is on your New Year agenda, it might pay to be mindful of a study suggesting there is little hard evidence that mindfulness leads to weight loss.

Ohio State University researchers reviewed 19 previous studies on the effectiveness of mindfulness-based programs for weight loss. Thirteen of the studies documented weight loss among participants who practiced mindfulness, but all lacked either a measure of the change in mindfulness or a statistical analysis of the relationship between being mindful and dropping pounds. In many cases, the studies lacked both.

The single study that did quantify simultaneous weight reductions and increases in mindfulness showed no relationship between the two. Another study that documented participants' increase in mindfulness indicated that the intervention did not affect weight loss.

"There is an aura around mindfulness intervention in weight loss and yet we need to know, in this era of evidence-based medicine, what the data tell us," said Charles Emery, professor of psychology at Ohio State and senior author of the study.

"There are many reasons to think mindfulness would be relevant for weight loss because people may have a range of behavioral and psychological responses to eating that mindfulness can address, including helping them slow down and focus on enjoying a meal," Emery said. "But our review of the research shows we still have a long way to go to provide convincing evidence of the benefits of mindfulness for weight loss and, especially, how it may work. "

To be clear, the research review is not meant to knock the pursuit of weight loss or of mindfulness as a New Year's resolution - or ever.

"Any effort to make behavioral change should be applauded," Emery said.

Emery conducted the analysis with KayLoni Olson, a graduate student in clinical health psychology at Ohio State. The review is published online in the journalPsychosomatic Medicine.

Mindfulness originated in East Asian tradition and reflects the Buddhist concept of mindfulness meditation. For overall health, mindfulness is thought to help with self-control and regulation of sleep and emotions. In the context of weight loss, mindfulness could help with management of behavioral changes that many equate to punishment - monitoring food intake, increasing physical activity and avoiding stress eating, for example.

The researchers set out to analyze previous studies of weight-loss interventions that included a mindfulness component. A key criterion for eligibility: Weight had to be measured at the beginning and end of the study.

From an initial keyword search that yielded 353 potential studies, the researchers identified 19 studies - 12 published in peer-reviewed journals and seven unpublished dissertations - that satisfied their requirements. They categorized the studies according to research methods used, and found that none met what they considered the gold standard: a randomized controlled trial that included measures of both mindfulness and weight at baseline and completion, as well as statistical analyses evaluating the relationship between mindfulness and weight loss.

Established ways to measure mindfulness include self-reports, time spent in mindfulness practice or number of mindfulness practice sessions.

"We were pretty loose in our definition of mindfulness intervention," Emery said. "In two good studies that documented decreased weight in the mindfulness group and not in the others, the mindfulness intervention was only one session. That's nice, but it further makes you ask: Is a change in mindfulness the mechanism by which that kind of intervention works?"

The combination of mindfulness with other interventions was an additional complicating factor in determining the specific effects of being more mindful on weight loss.

"There are many interventions that incorporate a mindfulness component, but that means weight loss could be explained by factors other than mindfulness," Olson said.

Emery and Olson note that their review raises important research questions about mindfulness and weight loss that remain unanswered: Does being mindful reduce stress and related problematic eating and if so, is it the best intervention available? And if meditation practice, which is a component of mindfulness interventions, leads to eating more slowly, is that about being mindful or just a serendipitous behavioral change?

"Because the data provide some support for the utility of mindfulness for weight loss, we think it's important to find out why," Emery said. "Depending on the mechanism involved, there may be ways of modifying interventions to make them even more effective. If behavioral changes are triggered by mindfulness, there may be additional direct ways to bring about change."