How fat can pandas get?

Pandas are cool and fat because they spend nine hours of their day eating up to 30 pounds of bamboo. Now, this alone wouldn't make them fat, as they only absorb about 20% of the total nutrients within the bamboo. However, what they do besides eat for 9 hours is sleep. They walk a little bit, but decide that any inclines are things they don't want to deal with. Basically they're fat because they're lazy.