Lots of useful, and some humorous, info in this thread. That watch is REALLY cool - however, I think its calorie count for riding motorcycles is off. Its basing calories burned on the data its getting from your heart rate, but normally when your heart rate goes up its because it needs to work to supply fuel and oxygen to other muscles which are also working (like your legs if you were bicycling or running or hiking). In the case of riding a motorcycle, those other muscles (with perhaps the exception of your sphincter) aren't burning calories, just your heart is. Your heart is indeed burning more then it would at your BMR (basic metabolic rate, ie. resting) so there is _some_ caloric benefit, but... The watch knows you are not doing one of those, which is good or you would get a really false reading as was previously pointed out, but I still think its reading high in terms of calories burned.
As someone who has lost almost 40 pounds (was 210-212, now 172-174) I can say that I was heavy when I exercised, and that diet alone does lower your metabolic rate. While you *can* lose weight using just one or the other, your will be more successful if you can incorporate both - and the best thing is to start tracking it all, because you will be amazed and just what we shove in our mouths (hence why exercise alone usually doesn't work - you work out, you get hungry and you eat, and you have a weight issue already, which means you usually eat too much, which will undo all the exercise).
