Weight loss surgery curbs sugar craving by acting on the brain's reward system, a new study has found.
The researchers found that gastrointestinal bypass surgery is used to treat morbid obesity and diabetes, reduced sugar-seeking behavior in mice by reducing the release of a reward chemical called dopamine in the brain.
"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," said senior study author Ivan de Araujo of Yale University School of Medicine.
Bariatric surgeries are more likely to succeed when patients substantially reduce their caloric intake, and reducing sugary foods is an important part of these behavioural changes.
The researchers found that positive outcomes are more likely if sugary foods seem less rewarding after surgery.
Patients have reported a change in the type of food they preferred after weight-loss surgery.
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Building on past studies that showed that the brain dopamine reward system regulates caloric intake as well as findings from his team that nutrient sensing in the gastrointestinal tract stimulates dopamine release in the dorsal striatum, de Araujo set out to test whether bariatric surgery relies on the same brain circuitry to curb sugary food preference.
They performed surgery in mice to bypass the first part of the small intestine, directly connecting the stomach to a lower section of the gastrointestinal tract. The same procedure is performed in humans, but no gastric pouch was constructed to limit food intake.
But bypass surgery inhibited the sweet-seeking impulse, almost as if it prevented the sugar addiction from taking hold.
"Our findings provide the first evidence for a causal link between striatal dopamine signalling and the outcomes of bariatric interventions," de Araujo said.
"However, ultimately we would like to help patients lose weight and reverse their diabetes without going under the knife," de Araujo advised.
The study was published in Cell Metabolism.