HRMs and MFP Calculations, is MFP close enough?

Do you know how to use your Polar? If the battery in the strap is okay (is it fairly new?) then go to the Polar website for the instructions on how to use it. Mine still works after ten years of having it.

With that said, if you deduct your RMR from the numbers the Polar gives, it was really close to MFP's numbers.

Here's what I do after futzing with the Polar, a step tracker, and MFP, and getting tired of the nuances:

I log 300 calories per hour of moderate exercise no matter what that exercise is. It works fine. I lost most of my weight doing that, and I used to do quite a bit of zumba - kinda dancey.

I looked at a few website calculators, used my Polar and finally got tired of messing around with it all and just started doing that. I mean, unless you are doing steady state cardio for a long time, the HRMs are pretty usueless too. And you really need to input your VO2 max for it to be close...I know, and then!! You'll likely make 200 plus calorie per day errors in food logging anyway, even if you make all your own food.

Just keep records as accurately as you can. Turns out that's good enough if you're consistent.

Here's a good blog about HRMs:

https://www.myfitnesspal.com/blog/Azdak/view/the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472

I've found my Polar close to MFP's estimate for some activities in the MFP database, and fairly far off for others. It's been ~3 years since I was comparing my routine activities, so I don't recall which were which.

I'm suspicious of the MFP entries that don't have any kind of metric: I think things like "gardening, general" are iffy because there's a big difference between casually weeding the carrots, and double-digging a new veggie bed. For the aerobic dance type stuff, I could be just going through the motions or really bringing it, and I don't know what vigor assumption is built into the MFP entry. Walking or cycling X mph may be a little closer, but what kind of cycling matters (road vs. trail, type of bike, etc.).

Worse yet, the HRM isn't accurate for all activities, either: It's best for steady state cardio activity, not as good for intervals, and really not as good for anything that isn't cardio (can be really far off for strength training, for example).

If you have a HRM that knows your actual VO2 max, or your actual max and resting heart rate (and you know your actual max, which most people don't), it will be likely to give you more accurate calorie estimates for cardio than one that estimates your max heart rate based on age (the age-based formulas are inaccurate for quite a few people).

It's important to remember that a HRM doesn't measure calorie burn. They measure heart rate, and use algorithms to estimate calorie burn. They'll be confused by anything that raises your heart rate but doesn't involve burning more calories. Some examples of things that raise heart rate without increasing calorie burn are hot weather, dehydration (doesn't have to be life threatening ), physical strain (as in weight lifting), and fear/alarm, among others.

If there are activities you do routinely, pick an estimating method, and stick with it. After 4-6 weeks, you'll have enough weight-loss data to adjust your intake if necessary to get a sensible loss rate.

Estimating exercise calories is worth doing, but it's important to think about the limitations.