I don't know if anyone here is into fitness or nutrition, but...

I need (want) to lose ten to fifteen pounds of fat. I've been exercising, though not always seriously, most of my adult life. With this in mind, I was quite surprised to learn (via a special test at my gym) that my anaerobic threshold (AT) is very low--113 heartbeats per minue. (The anaerobic theshold is the point at which your muscles are using more oxygen than your heart and lungs can deliver. Since stored body fat requires oxygen to burn, your muscles go from burning fat to burning glucose for fuel.)

I'm currently taking a 6-week aerobic class called "O2 training." Some of the women in my class are older and fatter than me, but many of them have a much higher AT (140-165 bpm).

I had assumed that my threshold was at least 145--based on the not-so-scientific, "talk test" method (the point at which you can talk comfortably but no longer sing during exertion). At 113, I'm not out of breath AT ALL, I can talk, sing, whatever...and I could exercise at this level for hours on end if I had the time and the will. I never seem to have both simultaneously, though.

Staying below 113 bpm would be wonderful were it not for the fact that total calories burned is quite low at such a low heartrate. With hardly any calories getting burned overall, it becomes less meaningful that most of them are fat calories. If I work above 113, I'm burning more total calories--but almost no fat.

I know I can raise my AT by doing bursts of exercise above it. Any suggestions other than that?

I guess here is as good a place as any to post my most recent problem. Sorry I couldn't be a help to you OnlyNow...I just changed my daily workout from a 3 mile a day run, with about an hour of weight training and 45 min yoga, to a 10.5 mile run with the rest the same. I gained 10 lbs in this first week, but not of muscle (maybe 1/3 muscle). Not only did I increase my run I cut my calorie intake about 300 calories a day (to about 1500), and increased my water intake to about 160 oz/day. How is it even possible that I gained weight?

You need to cut your calories by 3500 per week in order to loose one pound of fat per week. Pay special attention to calories you may be consuming and not even knowing it, such as liquids.

I know a gram of fat is what 9 calories or something, so the 3500 calorie/lb of fat makes total sense, but then how the hell did I gain 10lbs this week if the total calories consumed was about 11000? I like to think that a 10 mile run burns at least 500 calories, and I count all liquids in my calorie count. It is driving me crazy. My weight gain like isn't mathematically possible.