We’re mere days away from the most wonderful time of the year. I’m referring, of course, to Fat Bear Week. Every year, wildlife officials in Alaska’s Katmai National Park hold this annual single-elimination tournament celebrating the park’s fattest bears during their pre-hibernation feasting period. This year’s Fat Bear Week takes place from September 29 to October 5, and I’m ready—but I’m jealous, too. I’m jealous of these bears who get to double their body weight, stumble into bed, and snooze the frigid winter days away. Meanwhile, I’m over here consuming a calorically consistent diet with the knowledge that I’m still gonna have to walk to the bus stop when Chicago temperatures hit zero. Why shouldn’t I join in the fun? Why shouldn’t I, a normal human lady, be able to train my body to enter hibernation mode until the spring? I pestered a few experts to find out what the human equivalent of a hibernation diet might look like.
How much do bears eat to prepare for hibernation?
Bears’ pre-hibernation phase is referred to as “hyperphagia”—literally, “excessive eating”—and begins in midsummer or early fall depending on the animals’ region. During hyperphagia, bears consume truly stunning amounts of food in order to pack on body mass for hibernation. Per the North American Bear Center, black bears with unlimited food and water ate between 15,000 and 20,000 calories per day and drank several gallons of water to help flush out waste. With that kind of feasting schedule, the average bear packs on around 30 pounds a week, effectively doubling its body weight over the course of about 26 weeks. Bears then use all of that stored fat to power their basic functions during their cozy winter slumber, which typically lasts between five and seven months. During that period, grizzlies and black bears don’t eat, drink, defecate, or urinate. Just vibes, baby. Just vibes.
How much would a human have to eat to prepare for hibernation?
Hypothetically, if I, a lady of average heft, were physically able to hibernate, I’d need to double my body weight and gain about 155 pounds. (She’s revealing her weight on the internet!!!!!! Prepare the crash cart!!!!!!!!) That’s 155 pounds of pure fat, which, by traditional calculations, equals about 542,000 extra calories on top of my current ~2,000 calories a day. If I nixed my daily workouts, remained intentionally sedentary, and consumed 5,500 total calories a day, I could presumably put on about seven pounds of fat in a week. That’s 155 extra pounds in about 22 weeks, putting me roughly on par with Katmai National Park’s award-winningly plump bears. (For the record, there’s a whole community of YouTube bodybuilders focused on “making gains” by consuming roughly this same amount of calories.)
But how could I ensure that my 5,500 calories were building fat efficiently? To answer that, I checked in with Ricci-Lee Hotz, MS, RDN, a nutritionist and in-house expert at Testing.com. Hotz recommends consuming “foods with a high caloric and nutrient density such as fats (things like nuts, seeds, peanut butters, avocado),” because they could, hypothetically, help achieve the desired intake with less gut-busting volume. Of course, as Hotz points out, “high-fat and high-sugar desserts, as well as animal proteins, can also be helpful in getting dense calories without a lot of excessive volumes.” Hotz did feel the need to warn me that her suggestions were “helpful for the hypothetical goal, but are not focused on healthy weight gain and could result in health problems if attempted without medical and registered dietitian support.” Of course. This is purely fodder for my daydream about becoming a bear.
How hibernation impacts the body
After my chat with Hotz, I was feeling good. Feeling hypothetically capable of hibernation. But then I heard from Carl Borg, an environmental expert and the founder of outdoor resource Outforia. Borg assured me that humans simply can’t achieve the “controlled comatose state” that bears achieve during hibernation. Turns out that bears aren’t just sitting around playing bear video games during hibernation; their bodies instinctually reduce their oxygen consumption and metabolic rate by as much as 75% throughout the hibernation period.
Hibernating bears also experience significantly reduced blood flow to skeletal muscle, particularly the legs, which could prove harmful for humans. “The human body works in such a way that we can only lie in bed for a week before our tissues begin to atrophy, while hibernators have evolved to endure months without moving,” Borg says. Finally, bears have evolved to form a “fecal plug” in their intestine up to 2.5 inches in diameter during hibernation. Try as I might, I couldn’t get any wildlife experts to instruct me on growing my own. I hate science!
Boo! This sucks!
According to Borg, humans can’t hibernate because we’ve never needed to, which is a good thing.
“Evolution made humans an endothermic species whose sebaceous glands regulate their own body temperature by generating internal bodily heat,” Borg says, explaining that this mechanism keeps the body warm without burning excessive fat stores. “Since early humans did not need to burn precious fat stores to survive winters like many animals, human brains consequently tripled in size, enabling humans to use their intelligence to their advantage.” Early civilizations then harnessed fire, hunting, and gathering to form productive societies.
“When early human settlements predicted food scarcity and low chances of survival in their residential area, they simply migrated to a more accommodating environment,” Borg says. No plug required.
Ultimately, my hibernatory quest was futile. Theoretically, would I enjoy snoozing through the darkest days of winter? Yes, yes I would. But I’d also probably miss out on those evolutionary pleasures that make humanity what it is—namely, scowling on my couch in mid-January watching reruns of crime procedurals. Maybe I’ll give that 5,500-calorie diet a try.