I’ve gained 5 pounds since last summer. My body mass index (BMI) is still fine, but I need to stop gaining to keep it that way.
Grizzly bears put my weight gain to shame. In the late summer, they eat some 50,000 calories per day and gain more than 100 pounds. Then, when they hibernate, they fast and live on their body fat. While sleeping the winter away, they don’t pee or poop. They conserve their energy by having heart rates around 15 beats per minute. While hibernating, the sows give birth and nurse their young – activities all fueled by what they ate in the fall. When they emerge from their dens in the spring, the bears are much slimmer. In short, their “before” and “after” pictures are quite different.
Here’s the simple version of how grizzlies manage their huge weight transition. They first succumb to diabetes and then reverse slipping into that state. We know when they do this -- researchers are now investigating how they manage the trick.
Drs. Lynne Nelson and Charles Robbins of Washington State University work with grizzlies kept in the only research-based grizzly colony in the country. They study the bears as they go through their annual transformations. In the fall, when the bears are packing on the pounds, they are fed commercial kibble supplemented by such things as salmon, venison and apples. The bears also have access to a grassy meadow.
“Grizzlies are grazers,” Nelson told me. “People don’t always think of that, but they eat a fair amount of grass.”
One secret to how grizzlies manage to stay healthy while becoming obese is that they have a lot of “good” cholesterol. And their cholesterol levels don’t change much when they pack on the pounds. Studying how they do that could one day help with interventions in human medicine.