With commentary by lead study author Marci E. Gluck, PhD, a research team member with the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health
When machines aren’t working right, sometimes a gentle push gets them back on track. That’s essentially what researchers in Phoenix, Arizona, just did with the brains of people with obesity, ultimately helping them eat and drink less and lose weight.
“Previous studies from our lab found lower levels of activation in the DLPFC after a meal in obese compared to lean people,” explains lead study author Marci E. Gluck, PhD, adding that this brain region affects reward processing and executive functions such as planning and decision-making. “We used that information to hypothesize that activating the DLPFC in people who are obese might improve their ability to make healthy food choices, and as a result, lose weight.”
In the study, published in the journal Obesity in November, Gluck and her team administered non-invasive brain stimulation—transcranial direct current stimulation (tDCS), which uses a constant, low current delivered directly to the brain via small electrodes—to a small group of people with obesity for 40 minutes a day on three consecutive days, while another group got a sham treatment. For the next three days, the participants chose their own meals from a special vending machine with a built-in computer to log energy intake. The researchers did this sequence twice, first using “cathodal” stimulation, which decreases excitability, making neurons less likely to fire; then switching to “anodal” stimulation, which increases excitability, making neurons more likely to fire.
Predictably, the cathodal stimulation didn’t improve participants’ eating behaviors. But after the anodal treatment, participants ate less—about 700 fewer calories, specifically from fat and soda, and lost more weight—.2 percent of their body weight, in less than nine days. The group that got the sham treatment for both sessions showed no changes in their eating and drinking, and their weight didn’t budge.
“Because self-control in reward-related decision-making tasks depends critically on the activity of the DLPFC, we think that anodal tDCS could have reduced food intake by suppressing food cravings,” says Gluck, “or that those who received anodal tDCS may have been able to exert greater control over their food choices, resulting in decreased intake and healthier food choices.”
While brain stimulation seems incredibly promising for obesity—it’s certainly easier, cheaper and safer than say, gastric bypass surgery—it may not be available anytime soon as a mainstream treatment. Gluck, a research psychologist, says we’ll first need more studies showing the same results with more people and over longer periods.
Gluck’s team has a larger study already in progress, examining food intake and weight loss using active compared to sham stimulation in people with obesity. The device they’re using to administer tDCS in this larger study is portable, so if future studies show promising results, tDCS could be used outside of a medical setting.
“Just as the light box became a home intervention for treating seasonal affective disorder,” Gluck says, “tDCS potentially could be used at home to treat weight-related disorders in combination with regular physical activity and healthy eating."