CAMBRIDGE, United Kingdom — How are those New Year’s weight loss resolutions going so far? For people who need more motivation to cut the fat out of their diet, a new study finds your average elephant is probably in better shape than most humans. An international research team says, despite their massive size, zoo elephants actually carry less body fat than the average person.
The team, led by Daniella Chusyd of Indiana University, wanted to understand why Asian elephants (Elephas maximus) living in zoos had lower birth rates than their peers in the wild. Researchers say it was thought these captive elephants were overweight and this was leading to a fertility crisis among the zoo population. Such a connection is similar to what health experts see happening in overweight people.
“I was interested in discovering whether methods predominantly used in human health research could help us learn more about elephants,” says Chusyd, formerly from the University of Alabama at Birmingham (UAB), in a media release. “Obesity is not clearly defined in humans, let alone elephants.”
How do you check if an elephant is obese?
Until now, study authors say no one had ever checked how much fat Asian elephants carry in captivity.
Chusyd, Janine Brown from the Smithsonian Conservation Biology Institute, and Tim Nagy of UAB measured the amount of water in the elephants’ bodies. They then subtracted that from their body mass to calculate each animal’s level of fat.
It may sound simple, but measuring body water in an elephant is no small task. The best method is by giving each animal a dose of heavy water, however, the team had to be creative in their approach so the elephants wouldn’t spill the liquid.
“We came up with the idea of using bread soaked with heavy water to deliver it to the elephants,” Chusyd explains.
The researcher adds that elephants particularly enjoy this treat.
“I quickly became their best friend.”
Zoo keepers also collected blood samples prior to the heavy water treatments and up to 20 days after the experiment. Researchers examined elephants from zoos around the U.S. and Canada for this study. With help from scientists at the University of Aberdeen, researchers successfully calculated the water and fat content of these creatures.
Are you fitter or fatter than an elephant?
The results reveal that obesity is not to blame for lower birth rates among Asian elephants in captivity. In fact, the average male elephant carries slightly less fat (8.5%) than females (around 10%). In comparison, researchers find the average human carries between six and 31 percent body fat.
Overall, fat in female elephants ranged from two to 25 percent. Males in the study were larger and carried more total fat. However, does this mean zoo elephants aren’t fit?
To test their fitness, the team attached an elephant-sized fitness tracker to their legs. The gigantic wearable device measured how much walking each animal did each day. The results reveal, even in a zoo, elephants walk about the same distance daily distance as free-ranging elephants — between 0.01 and 1.7 miles every hour. The youngest elephants in the group walked the farthest.
When it comes to the potential fertility crisis at zoos, researchers say they were surprised to find infertile females carried the least fat. The results appear to be more similar to disrupted fertility cycles in underweight women. When looking at elephant insulin levels, fatter elephants tend to have the highest amounts of insulin.
“It is possible that elephants could develop a diabetic-like state,” Chusyd suggests.
“They are doing a great job… they know their individual elephants best,” Chusyd says of the zoo keepers.
The study appears in the Journal of Experimental Biology.