Just figured out exactly why I stopped losing weight.

Plus, if you are circuit training you get cardio as well as resistance training and burn mega calories. Have you ever done Jillian's Shred? I mean, I am dripping in sweat after 25 minutes. I am sure I burn at least 350 calories.

250 calories in 15 minutes sounds awfully high.

What kind of HRM did you get?

Ya really! I WISH! I am a ball of sweat most days and depends on the workout, it varies! But thats alot of cals burned in a small amount of time

I have a Polar f6 and worked with my trainer today for 30 minutes with 8 - 10 - and 12-lb weights. My HRM said I burned 186 calories during that time. I was also on the Bosu doing some jumping off and on which really got my heartrate up! That does sound like a huge burn for 15 minutes. ;-)

Weight training also burns more calories after you stop working out, just to point out......

Just for giggles, I popped on the weight machine dialed in the max it does 180 and for 15 minutes popped off bench and lat pulls, and other various exercises on it. Total calories burnt: 138. I'm inc. large and using max that machine had as fast as I could crank out 15 reps at a time. I held my HR at 158-163, I use a polar FT40, I think you might have you VO2 MAX set on the default, you need to do a quick est. VO2 MAX test and make sure that is set right, otherwise it'll give you some weird numbers. I learned that when I first got my polar. I just thought, ehhh default should work. Yeah you will want to change that. It takes 12 minutes or so to do the test for the most accurate results.

I have my HRM set up for Own Zone with all of my personal statistics - age, weight, etc.

What is endo/mesomorph?

One of the ways you can tell if you are getting accurate info and eating enough while lifting is assessing how you feel. If you are not able to lift heavier each time or you start getting sick and feeling tired all the time you are not eating enough, specifically protien. You want lean protien for this. It is actually very difficult to gain muscle if you are in a calorie deficiet, and if you are in too much deficiet then your body will start grabing protien... from your muscles, hence the tiredness, non-progresion, and sometimes even weakening can occurr. The more overweight you are the more likely you can gain muscle while losing fat. In short if you start feeling weaker, extra tired all the time and ar getting sick, then you need to eat more. Esp protien, but try for lean protien., you may actually need to adjust your ratio of macronutrients.

Speaking of macronutrients. Keep in mind when I say carbs I mean starchy low nutritional value stuff like grains, pasta, potatos; sugars and corn. I try to avoid carbs at night unless I'm weight training, and I also try to aviod them on non weight training days., though I usually find myself STARVING the day after weight day and I lift heavy. 5X5 each of Squats, Bench, Rows and then the alt work out of Squats, Overhead Presses and Deadlifts. google 5x5 and check the thread on MFP.

What the other poster meant about burning calories long after your lifting session is over is that the body, on that day continues to burn calories at a higher rate, for much longer than standard cardio. This is also true of High Intensity Interval Training (HIIT) and Circuit training as well.