A Single Dose of Oxytocin Nasal Spray Helps Overweight Men Improve Self-Control

The “love” hormone could help with weight loss.

Dubbed the “love” or “hug” hormone, oxytocin is released in our bodies when people cuddle, hug, or socially bond with one another — it makes us feel good.

Since the hormone has positive effects on relationships, researchers have been looking into its potential to help troubled couples patch up their relationships, and studies have shown that oxytocin nasal spray can lower stress and promote feelings of friendliness and trust.

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Now, researchers from Massachusetts General Hospital have found an intriguing new potential use for the nasal spray that has nothing to do with love or friendship. Instead, it has to do with helping overweight men improve their self-control.

Oxytocin nasal spray is a synthetic version of the hormone oxytocin, which the researchers say is important for controlling food intake and weight. Right now, it’s approved in Europe, but not in the US other than in clinical trials. In either an intravenous or injectable form, an oxytocin drug (Pitocin) is used to induce labor.

Last year, the researchers from Massachusetts General Hospital reported that oxytocin nasal spray reduced the intake of calories and fat during a test meal without affecting appetite, but they weren’t exactly sure how the drug had this influence.

In a new study, the researchers measured participants’ ability to suppress impulsive behavior with a psychology research test called the stop-signal task. This test involves sitting in front of a computer and responding to a square symbol on the computer screen by hitting a designated left button on the keyboard, and hitting a button on the right when a triangle symbol pops up on the screen.

After the participant became familiar with the task, they were told to hold back from pressing a button when heard a beep — the stop signal — along with a symbol. Since the beep sounded after the symbols popped up with a varying delay adjusted to each new subject, the new task required the participants to control their behavioral impulse to respond by hitting the button.

According to Franziska Plessow, an instructor in medicine at Harvard Medical School and a research fellow in the Neuroendocrine Unit at Massachusetts General Hospital, the results of the study in 10 overweight and obese men suggest that the way in which oxytocin lowers food intake is by improving self-control.

The participants took the test two separate times — one after they self-administered a dose of oxytocin nasal spray in each nostril and a second time after they unknowingly self-administered a placebo spray.

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The study, which received grants from the National Institutes of Health-funded Boston Nutrition Obesity Research Center and the Nutrition Obesity Research Center at Harvard, showed that the men acted less impulsively and exerted more control of their behavior after receiving a dose of oxytocin.

"Knowing the mechanisms of action of intranasal oxytocin is important to investigating oxytocin as a novel treatment strategy for obesity," Plessow said in a press release. "This information may allow us to move forward to large clinical trials, identify who can benefit from the drug, and help optimize the treatment."

Plessow said that future research is necessary to figure out exactly how oxytocin alters self-control, and the drug will also need to be tested in women.

"Our preliminary results in men are promising," she said. "Oxytocin nasal spray showed no strong side effects and is not as invasive as obesity surgery."