Could a love hormone help men eat fewer calories and keep the pounds off?

New research suggests a single treatment of a synthetic nasal formulation of the hormone oxytocin could cause men to follow a healthier diet, The Endocrine Society reported. The findings also showed oxytocin improved metabolic measures, such as insulin sensitivity, in these patients. The nasal spray in currently approved in Europe, but not in the U.S., other than in clinical trials.

"Our results are really exciting," said lead investigator Elizabeth Lawson, assistant professor of medicine at Harvard Medical School, Boston. "Further study is needed, but I think oxytocin is a promising treatment for obesity and its metabolic complications."

The recent study looked at 25 healthy men with an average age of 27. Thirteen of the study participants had a healthy weight and 12 were either overweight or obese. The men were assigned to self-administer a dose of either oxytocin nasal spray or a placebo after fasting. One hour after the treatment, the men were served a breakfast in which they were asked to select one double portion meal off of a menu. Following the meal the researchers calculated how many calories each participant had consumed. In a second portion of the experiment, the men's treatments (oxytocin or placebo) were switched, and they were served the meal again.

The team determined that, on average, the participants ate 122 fewer calories and nine grams less fat after they received oxytocin nasal spray. They also found the oxytocin increased the body's ability to use fat for fuel. There were no observed side effects associated with the oxytocin nasal spray.

The researchers noted that since oxytocin has sex-specific side effects, its influence on women's caloric intake requires study, and further research on its long-term use is also required.

The findings were presented at the The Endocrine Society's 97th annual meeting in San Diego.