Fat Bear Week is one of the year’s gems, and it kicked off in Alaska this week. For the uninitiated, it’s an annual competition where the public votes for their favourite chunky brown bear in the Katmai National Park and Preserve. The portly mammals haven’t been letting themselves go – they’re bulking up ahead of their winter hibernation. How they can stay healthy despite being overweight and sedentary for months has long puzzled scientists. New research has identified particular proteins in bear blood that increase during hibernation and allow them to maintain their muscle mass while shedding the kilos – a finding that could one day be used to treat diabetes and other metabolic disorders in humans. But back to the fat bears – there are 12 in the running for the crown, including 4-time winner Otis, the 635kg Bear 747, and the aptly named Chunk the Hunk. May the best bear win…