calories expended

I've found them to be not very accurate. Also with some machines it depends how you use them, also.

For example, some people hold on using the treadmill - the machine doesn't know this so it gives a reading based on calorie burn without holding on when in fact if you hold on you burn way less.

Same with ellipticals and using legs only etc.

Against my HRM, treadmill has me out by 100-200 calories on a decent run (5-10k @ 6.7-7.5mph) and the elliptical sadly can almost double my calorie burn. On the recumbent bike this am, the bike said 84 cals and the HRM said 26.

My advice would be to either log less than the machines say or invest in a heart rate monitor - especially if you eat back exercise calories