Grizzly Bears

A Metabolic Gift for Gaining Weight and Hibernating

For some of us, gaining weight (especially at this time of year) is a metabolic curse. But there are individuals for whom gaining weight is a metabolic gift and, in fact, essential for surviving in good health. In this case, we are thinking about grizzly bears. These animals gain tremendous amounts of weight every year as winter approaches. Hyperphagia drives them to eat incredible amounts of food in the fall (say, 30,000 calories per day) and effectively double their body weight.

This is weight cycling that’s essential for survival. And they have a metabolic gift for gaining all that weight without any risk of diabetes or other health complications that humans suffer.

Clues for Understanding Diabetes and Obesity

Researchers at the Washington State University are working hard to understand exactly how they do this. Their research may give us clues to understanding why humans are so vulnerable to obesity these days. Even better, it may lead to understanding how we can better protect ourselves.

The most recent research from this group comes from Michael Saxton and colleagues. They identified eight serum proteins that drive a genetic response in hibernation to control insulin sensitivity. This metabolic pathway can tell us a lot about how these bears hibernate in good health.

Healthy Obesity?

Nope, this is not healthy obesity. This is an expression of normal metabolic health for grizzlies. As we’ve noted before, the terminology of metabolically healthy obesity is problematic. It presumes that obesity is defined purely by BMI. Likewise, the chatter about an “obesity paradox” misses the mark. Folks who pursue these tangents forget that impairment of health due to abnormal or excess adiposity defines obesity. BMI is a clue, not the definition.

And this is why the grizzly research might be so valuable. These bears gain tremendous amounts of weight, but they don’t have obesity or develop diabetes. They have an exquisite metabolic gift for gaining weight they need to survive the winter.

Implications for Us

Co-author Blair Perry explains why this research may be important for human health:

“We have a lot more shared at a genetic level with bears than you might expect. If we can figure out how they’re able to turn off insulin resistance, essentially make things work as they did before they went into hibernation, make that same thing work in human tissues, we might be able to develop new medications that can help humans to overcome insulin resistance, and avoid that progression down to type 2 diabetes.”

So, yes, we have a lot to learn about obesity from grizzlies. Simply because they gain lots of weight without suffering the effects of obesity.

Click here for the recent study by Saxton et al. For more research on this subject, click here, here, and here. Finally, for further perspective, click here, here, and here.

Grizzly Bears, painting by Albert Bierstadt / WikiArt

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December 24, 2022