Oxytocin makes men eat less, choose healthier foods

Can this hormone singlehandedly prompt the evolution of male humans?

First, we learn that the "love hormone" oxytocin makes men more trusting, nurturing and sociable. Then, we learn that a shot of the stuff makes partnered men less likely to stray or even flirt with other women. Now, we learn that a puff of oxytocin up the nose makes men eat less, and choose foods that are less fatty.

If there were a scientific conspiracy to turn men into cuddly, highly evolved salad-eaters, oxytocin might be a powerful weapon.

A study released Thursday found that 25 healthy men who got a dose of aerosolized oxytocin and then offered a man-sized serving of breakfast consumed fewer calories, decreased their fat intake, and showed improved measures of metabolic function such as insulin sensitivity.

The study, led by Harvard Medical School's Dr. Elizabeth Lawson, is to be presented in San Diego this Sunday at the annual meeting of the Endocrine Society, a leading group of hormone experts active in treatment and research.

The men served as their own control group: during one session a subject would receive a puff of ocytocin; at anotherm he would get a placebo.

“Our results are really exciting,” Lawson said. Although she said further study would be needed, she suggested oxytocin might be "a promising treatment for obesity and its metabolic complications.”

Oxytocin's role in fostering sociability has led to its preliminary use as an aid to teaching those with autism improved social skills. But new research is broadening understanding of the hormone's powers: last week, a study suggested oxytocin, which counteracts the inebriating effects of high alcohol intake, might help in the treatment of alcoholism, and possibly other addictions.

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