Chalk up another benefit to weight-loss surgery. A new study has found bariatric procedures — such as gastric bypass — curb the sweet tooth by acting on the brain's reward system, reducing sugar cravings.

In new research reported in the journal Cell Metabolism, Yale University School of Medicine scientists found that gastrointestinal bypass surgery, which is used to treat morbid obesity and diabetes, reduced sugar-seeking behavior in mice by reducing the release of dopamine in the brain.

The findings suggest the change in brain biochemistry may make sugary foods less rewarding after surgery.

"The problem of how and why bariatric surgery works has been perplexing scientists for years," says Yale researcher Ivan de Araujo. "By shedding light on how bariatric surgeries affect brain function, our study could pave the way for the development of novel, less-invasive interventions, such as drugs that reduce sugar cravings by preventing sugar absorption or metabolism upon arrival in the gastrointestinal tract."

Many people report changes in food preferences after weight-loss surgery, and some research has suggested such procedures may change the makeup of gut bacteria, which may in turn change brain signals tied to eating habits and food cravings.

But the latest study suggests weight-loss sugary also affects the brain dopamine reward system, tied to caloric intake. Specifically, the research team found that changes in gastrointestinal tract stimulate dopamine release in brain and impact the same biochemical circuitry that affects sugary food cravings.

"Our findings provide the first evidence for a causal link between …dopamine signaling and the outcomes of bariatric interventions," de Araujo said. "However, we certainly do not want to give the impression that we have an answer for how and why bariatric surgery works. Much more research is needed in this field."

Researchers now plan to compare the impact on the brain's dopamine cells produced by different types of bariatric surgeries — including gastric banding.

"We hope our work will provide new insights into how different bariatric interventions may lead to a diverse repertoire of behavioral modifications," de Araujo said. "However, ultimately we would like to help patients lose weight and reverse their diabetes without going under the knife."

This study was funded, in part, by the National Institutes of Health.