Could Brain Stimulation Fight Obesity?

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People with obesity could benefit from magnetic or electric stimulation of the brain that helps them to eat less, a new review of studies finds.

In the review, researchers looked at the latest work on two noninvasive brain-stimulation techniques, and found that for people with obesity, both electrical and magnetic pulses yielded promising, though very preliminary, results. The main target of the brain stimulation is usually a region called the dorsolateral prefrontal cortex, which is linked to dietary self-control, the review said.

For people with other eating disorders, such as bulimia and binge-eating, treatment with multiple sessions of noninvasive brain stimulation — usually magnetic pulses — may also have the potential to help. However, the researchers ultimately said the results were inconclusive. And when it comes to using the brain stimulation to treat people with anorexia, "the findings are quite mixed and less promising," said study lead author Peter Hall, a clinical psychologist and the director of the Prevention Neuroscience Lab at the University of Waterloo in Canada. [10 Things You Didn't Know About the Brain]

Much recent work has focused on the possible beneficial effects of noninvasive brain stimulation techniques, such as boosting creativity, enhancing math skills and helping patients recover from strokes. Two commonly analyzed techniques include transcranial direct current stimulation (tDCS), which applies electric current to the brain, and repetitive transcranial magnetic stimulation (rTMS), which uses magnetic pulses.

"There is a lot of interest in new techniques for treating disorders of eating, as many of our standard approaches [to treating eating disorders] don't work as well as we would like," Hall told Live Science.

In the review, the researchers looked at studies done on both tDCS and rTMS. They found in a number of those studies that stimulating the dorsolateral prefrontal cortex appears to decrease cravings.

In addition, three completed clinical trials and one ongoing one suggest that noninvasive brain stimulation can reduce food consumption and thus fight obesity. However, Hall and his colleagues noted that all these studies were short and had few participants, and that such work mostly highlighted the need for more clinical trials. [6 Foods That Are Good For Your Brain]

Hall and his colleagues also examined recent studies of people with bulimia and anorexia. Bulimia includes cyclical binge-eating episodes followed by purging behaviors such as self-induced vomiting or laxatives. Anorexia may also include binging and purging, but its hallmark feature is dangerously low body weight.

Some initial findings have suggested that rTMS may reduce short-term binging in people with bulimia, Hall and his colleagues said. However, no longer-term benefits have materialized yet.

When it comes to anorexia, they said the results have been significantly more unclear. For example, Hall and his colleagues noted one study where five women with long-standing anorexia were treated using rTMS. Although some of the patients noted improvements in their anxiety and stress levels, all of the women actually lost weight, averaging more than 5 lbs. (2.27 kilograms).

So far, the bulk of the research suggests that magnetic stimulation (rTMS) is more effective than electrical stimulation (tDCS), the researchers said.

"Direct current stimulation has received quite a bit more media attention, but has demonstrated weaker and less reliable effects on food cravings across studies so far," Hall said. "One implication is that while rTMS is already quite advanced and effective, tDCS may still be a work in progress."

A pattern may be emerging on whether noninvasive brain stimulation will have an effect on people with eating disorders, Hall said. For instance, binge-eating and bulimia are disorders that "involve loss of self-restraint in relation to high-calorie foods, whereas anorexia may arguably involve excessive self-restraint," Hall said.

In any case, noninvasive brain stimulation techniques are not ready yet to treat eating disorders, and should not be seen as a cure-all for these complex problems if they ever do reach patients, Hall said. "Instead, they might be very useful components to more comprehensive treatment packages when used very strategically," he said.

The scientists detailed these findings online March 11 in the journal Appetite.