Early research of a small number of men suggests that the "love hormone" oxytocin may reduce appetite, potentially leading it to become a new tool for weight loss.
For the study, researchers tested a synthetic nasal formulation of oxytocin and found the hormone treatment reduced the number of calories that men consumed, especially calories from fatty foods.
"We are seeing early signs that oxytocin reduces how much food someone eats at a meal and improves the way their body handles blood sugar," study lead author and assistant professor of medicine at Harvard Medical School in Boston, Dr. Elizabeth Lawson says.
The hormone oxytocin is linked to many activities that bond people together, including sex, hugging, kissing, holding hands, giving birth and breast-feeding. In medicine, it's used to induce labor, manage bleeding in mothers after birth and coax out breast milk in nursing women, Lawson says.
"Not much is known about oxytocin effects on appetite and food consumption in humans."
For the study, researchers randomly assigned 25 men (12 of whom were obese) to take either synthetic oxytocin via nasal spray or an inactive placebo. After receiving the hormone or placebo, the men ordered breakfast from a menu and they were given double portions of whatever they ordered. At the end of the meal, researchers measured how much food was eaten.
The men then returned to repeat the experiment, only they received the placebo if they took the oxytocin the previous time, or the reverse.
Researchers found that those who took the oxytocin at an average of 122 fewer calories. They also consumed less fatty food - about 9 few grams on average that translates to approximately 80 calories from fatty food.
There are some caveats to the study. For example, the researchers didn't explore if the men who ate less were hungrier later, and women weren't included leaving the affects on women still unknown.
The study, while small, still shows potential according to Paul Zak, founding director of the Center for Neuroeconomics Studies at Claremont Graduate University in California.
"From an evolutionary perspective, oxytocin is released during positive social interactions -- when we are around others who care about us. This is just when food sharing is likely to occur. If we want to lose weight, having others around us who care about us can help reduce appetite," he suggested.
Lawson agrees that more research is needed and plans to continue the study of the use of oxytocin before meals as a treatment for obesity, and researchers also want to better understand the effects in women.
