The ‘Love Drug’ Might Help With Appetite Control

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Photo: Darren Greenwood/Corbis

There’s a pretty widespread fascination with oxytocin, and for good reason: The so-called “love drug,” which promotes bonding between both romantic partners and mothers and their babies, may, according to early studies, have potential to provide all sorts of benefits when administered artificially via a nasal spray, from increasing feelings of warmth and good will to treating some of the symptoms of schizophrenia and autism.

Now we can (maybe) add an unexpected new benefit to that list: calorie control. In a study led by Dr. Elizabeth Lawson of Harvard Medical School, two groups of men were given a nasal spray to self-administer. Some of them contained oxytocin, while others were a placebo. Then, an hour later, they picked items from a menu and ate breakfast. During a return visit to the lab, the placebo group and the oxytocin group were switched, and the experiment repeated itself.

The results, from EurekAlert!:

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. There were no serious side effects and no difference in side effects between oxytocin and placebo, according to Lawson.

The men dosed with oxytocin didn’t report feeling less hungry, and the substance didn’t affect the levels of “appetite-regulating hormones measured in their blood,” so it’s unclear exactly what’s going on. In an email to Science of Us, Lawson offered up some informed speculation:

We used to think that oxytocin was only important in women for inducing labor and facilitating nursing. What we are learning is that oxytocin has important functions in both sexes. Evidence now shows that oxytocin is involved in social behaviors, mood, reproduction and regulation of energy balance. We don’t know for sure how all of these tie together, but one possible way to think about it is that when calories are readily available to the body, oxytocin favors social and reproductive activities.

In this view, then, oxytocin might have different effects on you depending on how recently and how much you’ve eaten. But Lawson and other researchers still have a lot to learn.

As for next steps, she said she and her team are “currently investigating the effects of oxytocin on other appetite-regulating hormones as well as brain circuitry involved in regulation of food intake in order to improve our understanding of how oxytocin works” — the goal being to figure out whether oxytocin has potential as a treatment for obesity and related conditions. (She also pointed out that they need to test it on women, too, to see if the effects are the same.) It might turn out that we’re selling oxytocin a little short by just referring to it as the “love drug” — it seems to do a lot of other useful stuff as well.