I have had grizzly tracks around my tent the next morning.
First, NEVER take any food into your tent.
If you've had food in your tent, I would suggest getting another.
In a similar vein, do not pack you tent in a pannier with your food.
Second, in bear country change out of your cooking/eating clothes.
You may not smell the food odors, but a bear can and will.
Third, learn to hang you food and toiletries in a bearproof manner.
Grizzlies are too large to get correctly hung packs,
But black bear cubs - esp, around Yosemite NP have figured out how to get them.
In areas with bad bear problems, you must use a bearproof cannister.
Most frontcountry campgrounds have bear boxes - -
But you should know how to hang your food - just in case.
Parks Canada - Appropriate for Northern Rockies, too -