Very true. I burn 1000 kcals in an hour of running on an easy day, and closer to 1300 during a tempo workout.

Also, the health benefits of cardio are numerous, ranging from stress reduction to neurogenesis to longer telomeres. It's not just about how good looking your body is.

700 kcals is on the extreme high end for an hour of cycling. You'd have to be fairly heavy already and pushing it as hard as you can go. A normal person putting in average effect is probably more like 250-300 kcal.

I weigh 145. 700 kcals is about "tempo" effort: hard, but still fun-hard. All out, in the best shape of my life for one hour is around 900 kcals. I'm in good, but not phenomenal shape; my brief flirtations with road racing ended in utter humiliation.

I know this because of my on-bike power meter, which measures mechanical work in kJ. That "perfect hour" was around 280 W, and I've done it twice. (Cyclists have a very narrow range of biological efficiencies, so you can just multiply mechanical by a constant to reckon metabolic work.)