I would say a 630 calorie donut is pretty huge. After looking at the calorie info for a bunch of Tim Hortons donuts, the average seems to be around 250 calories.
Sugar (and now HFCS) in everything magnify this problem. I wonder how much calories food would have if manufacturers reduced the amount of sweeteners. Probably makes the food taste worse though.
Come on down to the US and you will find 600 calorie donuts aplenty.