Calories

Buy a heart rate monitor. It doesn't have a be an expensive one. I have a Polar T4 and it seems pretty accurate in recording my calorie burns for rebounding, cycling, treadmill workouts and the like.

I bought an inexpensive heart rate monitor from Wal-Mart ($20) and log it under circuit training. I then average the number my heart rate monitor and MFP gives me and use that. I think MFP over estimates a lot.

Most heart rate monitors are accurate only for sustained aerobic exercise at a moderate to intense level. They're not accurate for activities where you start and stop a lot, or where your heart rate doesn't get up very high.

They work OK for running, cycling, cross-country skiing, rowing, etc. They won't be too accurate for walking, unless you're really out of shape. They're not good for calisthenics, yoga, weightlifting, and other activities where your heart rate isn't closely correlated with the activity of your large muscle groups.

They're not always that accurate for sustained exercise either. One study of the Polar F6 showed that, even calibrated with subjects' actual VO2max and HRmax, it overestimated energy expenditure by 27% (http://www.ncbi.nlm.nih.gov/pubmed/21178923). An earlier study showed that the Polar S410 overestimated energy expenditure in women by 12% (http://www.ncbi.nlm.nih.gov/pubmed/15292754). Another study found that the Polar S810i overestimated expenditure when exercising lightly but not moderately (http://www.jssm.org/vol9/n3/21/v9n3-21abst.php). The research seems to suggest that HRMs are less accurate for women than they are for men.