It’s long been known that the hormone leptin helps control hunger, but a recent study has revealed that it may also help govern what foods we like and dislike.

In the study, two teenagers who don’t produce leptin because of a rare disorder were given the hormone. Before getting leptin, they were insatiably hungry, and not choosy about which foods they ate. Once given the hormone, however, they began to discern favorite foods and reject others. The choosiness allowed them to lose weight. Lead researcher Paul C. Fletcher explained,

This work shows that the rewarding properties of food have strong effects on brain areas concerned with liking and desire, and that the tendency for some people to overeat because they like food is influenced by specific hormones and chemicals in the brain.

Leptin research will likely lead to a better understanding of appetite and obesity. But it’s also leading to some controversial suggestions, most notably “leptin babies.” A British scientist, Michael Cawthorne, is developing a baby formula supplemented with leptin, which would ostensibly help regulate how the body produces the hormone, essentially inoculating the child against obesity and its attendant health problems (diabetes, heart disease). This kind of tinkering makes some people deeply uncomfortable. Cawthorne argues,

How is it different from giving children vaccinations to prevent infectious disease? Obesity is a disease with life-or-death consequences. We need to do something about it, and it’s pretty obvious that what we’re doing isn’t working.

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