The hormone oxytocin in a nasal spray form may be used to treat obesity. The spray reduced caloric intake in healthy men, particularly consumption of fatty foods, after a single dose, a new study says.
Oxytocin nasal spray reportedly lowered the number of calories men consumed at a subsequent breakfast whether they were normal weight or overweight.
"Our results are really exciting," said lead investigator Elizabeth Lawson of Harvard Medical School, Boston. "Further study is needed, but I think oxytocin is a promising treatment for obesity and its metabolic complications," Lawson added.
In addition, the researchers found that oxytocin improved metabolic measures, such as insulin sensitivity, which is the body's ability to successfully clear glucose (sugar) from the bloodstream.
The oxytocin nasal spray (made by Novartis) is approved in Europe but not in the U.S. other than in clinical trials. Lawson and her colleagues enrolled 25 healthy men into the study, with an average age of 27. Thirteen of the men had a healthy weight, and the other 12 were overweight or obese.
The men were randomly assigned to self-administer a single dose (24 International Units, or IU) of either oxytocin nasal spray or a placebo (dummy drug) after fasting.
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All were unaware which treatment they received. One hour later, the men received breakfast, which they picked out from a menu. Each meal contained double portions. After the meal, the researchers measured how many calories each man ate.
On average, the men ate 122 fewer calories and 9 grams less fat at the meal after they received oxytocin nasal spray compared with placebo, the study data showed.
Oxytocin also reportedly increased the use of body fat as a fuel for energy. Oxytocin had no effect on self-reported appetite or on appetite-regulating hormones measured in their blood, the researchers discovered.
Therefore, how oxytocin affected caloric intake is unclear, Lawson said. The findings are scheduled to be presented on March 8 at The Endocrine Society's 97th annual meeting in San Diego.