I know some people use the wrist watch style monitors, or the monitors on tredmills. I dont believe they are very accurate, besides if your heart rate is up, you will know, and if your losing fat you should be able to tell via the scale.
I dont know that i would buy a monitor, but that seems like your only option if you want to monitor that closely.
I don't do this for my family, my friends, women, accolades, pride, or ego. I do it for me and no one else, its just part of who I am.