Men treated with the “love hormone” began to eat fewer fatty foods almost immediately, according to new work presented at the annual Endocrine Society meeting that took place in San Diego over the weekend.
The hormone oxytocin helps promote trust (and cuddling) between romantic partners as well as bonding between moms and their babies. In the U.S. for example, oxytocin is approved as an injectable drug to induce labor and facilitate nursing. And recent work with animals suggest that this same “cuddle chemical” promotes social behaviors in macaques and dogs, as well as sobriety in rats.
Well, now add weight loss to the list. “Further study is needed, but I think oxytocin is a promising treatment for obesity and its metabolic complications,” Harvard’s Elizabeth Lawson says in a news release. For their study, Lawson and colleagues recruited 25 men with an average age of 27 years: Just over half of these men had a healthy weight, while the other 12 were either overweight or obese. The men were randomly assigned to self-administer a single dose of either oxytocin nasal spray or a placebo after fasting. This synthetic oxytocin nasal formulation is approved in Europe, but not the U.S. except for use in clinical trials.
An hour after taking either the “love drug” or the dummy drug, the men got to pick what they wanted to eat for breakfast off a menu. Each meal consisted of double portions, and after breakfast, the researchers measured how many calories each man consumed. On another visit, the men repeated the same procedures, but with their treatments switched.
Turns out, after a single dose of oxytocin, the men (regardless of their weight) reduced their caloric intake at breakfast: On average, they ate 122 fewer calories and 9 grams less fat at breakfast, compared with men who received the placebo. Furthermore, oxytocin appeared to improve metabolic measures. It increased the use of body fat as a fuel for energy and insulin sensitivity—the body’s ability to successfully clear sugar from the bloodstream.
However, because oxytocin had no effect on the men’s self-reported appetite and no effect on the appetite-regulating hormones in their bloodstream, its effect on caloric intake is unclear for now. Although, previous studies have suggested that the hormone is somehow involved with certain pathways in the brain that reduce hunger.
Next, the researchers want to study oxytocin in women, since the hormone has sex-specific effects, and extended trials with both men and women will also need to be conducted.
