The only polar bear on public display in the UK was lured on to the scales with his favourite fishy treats to allow keepers to weigh him.
Walker was given a trail of sardines to follow to tempt him on to a large wooden platform attached to a set of scales which revealed he has gained around 330lb (150kg) in just over a year.
The three-year-old bear weighed in at 63 stone (403kg). When he arrived at the Highland Wildlife Park in Kingussie, Inverness-shire, in December 2010 he was around 39 stone (248kg). It will be another two or three years before he is fully grown. By the age of six he will weigh an estimated 80-110 stone (500kg-700kg).
After Walker's weigh-in, keepers checked his teeth and tongue and then allowed him to return to play in his enclosure with a hard hat, his favourite toy.
Una Richardson, head keeper responsible for Walker, said: "The weigh-in this morning with Walker went extremely well. We managed to tempt him on to the scales with a few of his favourites: sardines.
"We are really pleased with Walker's weight. He's a big boy at 403kg, which is around 63 stone. It's slightly higher than what we had expected. We guessed he could be around 62 stone, which is around 395kg.
"It's a good, healthy weight for a polar bear of his age and size and is close to the weight we had expected. After we took his weight reading he was off to play with his favourite toy - a hard hat - and enjoy the rest of his morning.
"Knowing precisely what he weighs gives us a very good indication of how well he is doing and, should we need to anaesthetise him for any reason or give him any medication, knowing what he weighs allows us to give him a more accurate and therefore a more effective dose.
"Weighing Walker is a two-person job. One of us has to be ready to take the weight reading and the other has to get Walker on to the scales."
Staff at the park, which is owned by the Royal Zoological Society of Scotland, said the UK could have a second polar bear on display by the end of this year. Ms Richardson said: "We have hopes of getting Walker a mate sometime this year but at the moment he is enjoying his bachelor lifestyle." However, Walker will not reach sexual maturity for at least two more years.