University of Michigan study reveals why male mice retain heat better

Researchers at the University of Michigan have discovered that testosterone and a skin protein called keratin 9 make male mice retain heat more efficiently, providing a biological clue for why women often feel colder than men. In experiments published in *Nature Communications*, the team altered hormone levels in adult mice and measured how quickly their bodies cooled after a brief exposure to a cold chamber. Male mice with normal testosterone levels lost heat 30 percent slower than females, while females given testosterone showed a similar slowdown. The effect disappeared when the researchers blocked keratin 9, indicating the protein’s key role in heat retention.

The finding matters because temperature perception influences daily comfort, workplace productivity, and health outcomes. Women regularly report feeling chilled in office settings, at home, or during outdoor activities, a complaint that has long been dismissed as “just a feeling.” Prior studies linked the difference to higher body fat percentages in women or to blood‑flow patterns, but none identified a molecular mechanism. Understanding why women get cold more easily could help design better heating standards, clothing, and even medical treatments for conditions like Raynaud’s phenomenon, where blood vessels over‑react to cold. The new mouse data suggest that hormonal balance and skin composition, not just circulation, shape how the body manages heat loss.

Lead author Dr. Maya Patel said the work opens a path to human studies that could confirm whether testosterone and keratin 9 act the same way in people. The team plans to measure skin protein levels in men and women across different ages and to test whether topical applications that boost keratin 9 expression can improve thermal comfort. If the results hold, they could lead to gender‑specific guidelines for indoor temperature settings or new dermatological products aimed at reducing cold sensitivity. For now, the study adds a concrete piece to the puzzle of sex‑based temperature differences, moving the conversation from anecdote to science.