For threatened polar bears, the climate change diet is a losing proposition

With Arctic sea ice shrinking from climate change, many polar bears have to shift their diets to land during parts of the summer

For polar bears, the climate change diet is a losing proposition, a new study suggests.

With Arctic sea ice shrinking from climate change, many polar bears have to shift their diets to land during parts of the summer. A study looking at Hudson Bay polar bears tries to figure out if they can keep up their roly-poly figure, which is what's needed and found that an overwhelming number of them are dropping the pounds no matter what they do to try to beef up their weight.

Some bears find a lot of food — berries, eggs, sea birds and even caribou antlers — but it takes so much effort, so many calories are burned trying to eat, that they end up losing weight and expending more energy than they take in, according to a study in Tuesday's journal Nature Communications.

Other bears go into a stage of semi-hibernation, don't do much, but they also shed the pounds, so either way doesn't work, said study lead author Anthony Pagano, a U.S. Geological Survey wildlife biologist.

Researchers found that 19 of the 20 bears studied dropped an average of 47 pounds (21 kilograms) over three weeks of being studied in research that monitored their calorie intake, energy use and respiration in the wild. That's losing about 7% of their body mass on average in just 21 days, the study concluded.