Originally posted to myfitnesspal.com on 8/14/11
In the world of instrument calibration there is an old saying: "The person with one clock always knows what time it is. The person with two is never quite sure." Monitoring weight loss and calorie burn seems to fall into this same category.
With weight loss, the solution seems relatively easy: always use the same scale. I've heard some concerns in the forum about not seeing weight loss or even seeing gain but admissions that they are using more than one scale. The clock analogy works great here because how often does your watch and the clock at the gym match? And pardon me for being a skeptic but I never trust scales at the gym. I think there is a vested interest in making you feel better about yourself when you're there. How often have you heard someone say "I like the scales at the gym better?" Not to mention that those scales take a beating and are more likely to be out of calibration. For the most accurate weight readings, I bought a good scale and officially take my weight readings once a week on the same day at the same time and under the same conditions (clothing, placement of scale on the floor, etc.) condition permitting.
Calorie burn is where I struggle. I try not to put too fine a point on my calorie consumption and burn because everything is just an estimate, and I usually try to stay about 200 - 300 calories below my daily goal as a rule. When I first starting logging here, I used the estimated burn for the activities but found that it differed somewhat (on the high side) from what my elliptical cross trainer was telling me. After reading some posts in the forums, I decided to take the worst case scenario and go with the lower calorie burn reading from my machine. However, I was on a similar elliptical cross trainer in a hotel fitness center this week and the calorie burn reading was much more in line with the MFP estimates. In fact, the distance traveled, speed and calorie burn were all quite a bit higher than a similar workout (approximately the same resistance and RPMs) on my machine at home. It would appear that the primary difference is the speed and distance traveled. I would think the calorie count would be more in line if those numbers matched. But why don't they when the RPMs are similar? The distance should actually be further on my home machine because it has a very long stride length. So, do I play the skeptic again and not believe the fitness center machine, even if it matches the MFP estimate (and isn't in a gym wanting my money)? Should I shift to the MFP estimate for my home workouts regardless of what my machine says? My elliptical is high quality (Smooth Fitness); shouldn't I be able to believe it even if two other sources tell me it's wrong?
My first step will be to contact Smooth Fitness to see if there is a way to recalibrate the computer. I did move the machine recently but I remember the readings being the same before the move. If that doesn't resolve issues, I'll probably go back to the worst case scenario. It would be better to underestimate the calories than go over and wonder why I hadn't lost any weight. Maybe I should just stick to one machine like I do with the scales.
Update: after reading many forum posts here on MFP, it appears that the HRM is the way to get the most accurate readings. If my elliptical is basing my calorie burn on my HR, it could be down because I have my hands on the grips less at home (messing with remotes, music, etc.). I do have a chest band HRM that I'm going to try and see if that makes a difference.
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