Hibernating Bears Hold Clues to Human Obesity

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Photo: Uriadnikov Sergei

When I close my eyes and imagine my best life, I think of bears. If I guzzled honey straight from the jar with my bare hands, people would call it a worrying sign of an unhealthy relationship with sugar, or at the very least gross; when they do it, it’s endearing. They can leave the house sans pants and no one bats an eye. Stealing picnic baskets, spouting bad jokes underneath a doofy hat, taking a break every so often to lecture strangers on fire safety — you have to admit, it sounds like a pretty good way to pass the time.

And then there’s the hibernation envy. Our species, unfortunately, is one that tends to frown upon extended food binges followed by very long naps — bad for your health, they say, and also for your status as a functioning member of society. Whatever. Bears go for it.

If you can’t join ‘em, though, at least you can learn from ‘em. As Erica Goode reported in the New York Times earlier this week, research on hibernating bears is having a moment — and it may yield some valuable information for the human fight against obesity.

Hibernation — in which bears and other animals completely sleep through the winter, without eating or drinking — requires a temporary but dramatic overhaul of the way the body functions. As Goode explained:

Hibernating bears, grown fat from summer feasting, do not eat, drink, urinate or defecate while they are hibernating. But they lose no muscle mass from inactivity. Platelets in the bears’ blood become less sticky, acting as a natural blood thinner, the researchers found, perhaps to counteract blood clots that could form during long periods of immobility. The bears’ metabolism drops to 25 percent of its normal state and their kidneys stop functioning, yet they do not have kidney failure.

Notably, bears’ response to insulin — a hormone that helps the body process blood sugar — also fluctuates depending on the time of year. In the summer, past research has shown, they’re more sensitive to insulin; during winter hibernation, they become more insulin-resistant — a state that’s linked to both obesity and diabetes in humans. In one study, scientists succeeded in making hibernating bears’ fat cells more sensitive by treating them with chemicals from summertime blood.

The study authors, Goode reported, “hoped such studies would eventually lead to drugs to treat diabetes or cure obesity,” but such real-life applications are still a ways down the road — particularly because in bears, insulin resistance doesn’t seem to carry the same negative health effects as it does in humans. In fact, “obese bears are healthier,” the veterinary professor Heiko T. Jansen told the Times. “They have all the advantages, which is so counterintuitive to human biology.” Once again, the bears are doing it better.