A grizzly with access to salmon will weigh more. The bears feed on carrion, salmon, trout, small rodents, insects, berries, succulent vegetation and roots. Since they can't digest fibrous vegetation, they are selective feeders.
Bears are highly intelligent and use complex problem solving skills to find food.
When they come in contact with humans they usually retreat, but will attack if wounded or cornered. Reports of bear attacks are generally exaggerated, or the result of a bear that was familiar with being fed by humans, as in a park. Bears usually den up, and spend their winter in the state of winter dormancy, called torpor. They do not truly hibernate. Walking plantigrade allows the grizzly to walk upright, therefore they are a more menacing foe, and have more access to food.