I just googled the term "Garmin 500 not calculating calories" and got a page full of the same complaints. Many forums, including Garmin's, have posts that address this issue so it's not just us. What I did read is that Garmin is aware of the issue and they will be coming out with a firmware upgrade to fix it soon. All I can say is just keep upgrading your Garmin when there is a firmware upgrade and see if it fixes the problem. Everything else on the 500 works great and I'm pleased with the computer in every other aspect.