“Food or sex, you have to choose one,” I remember one of the Friends’ characters pressing Joey in a corner. Joey struggles with it, moving from one to the other and so before saying, “both, I want women on bread.”

The people behind new research published in the journal, Cell Metabolism—neuroscientists Anne Petzold and Tatiana Korotkova at the University of Cologne in Germany—may well have been watching the legendary Joey Tribbiani in that Friends episode, because they have tried to find an answer.

Male mice were starved, their appetite suppressed with leptin, not given enough water, and then of course the conditions flipped, to observe the trade-offs.

More specifically they examined neurons in the hunger centre in the brain—the lateral hypothalamus—that are activated by leptin. Leptin promotes a feeling of fullness.

“Leptin is normally produced when an animal’s energy needs have been met, and that feeling of satiety could allow the animal to refocus its attention away from food and towards other interests,” explained Scott Sternson, a neuroscientist at the University of California, to Nature.

Fascinating research, and of course after prolonged hunger the mice would forego possibility of sex to seek food. However at moderate levels of hunger, it was the opposite choice.