Polar FT4 calories vs MFP calories

MinnieInMaine is right. I've used a Polar F7 model for upwards of 8 months before switching to a BodyMedia Link for a year. With my HRM, the more I worked out, the more weight I gained because I was eating back all my HRM-estimated exercise calories and primarily doing circuit weight training workouts and Zumba/Hip Hop classes with only a little C25K thrown in. I wore both my HRM (during exercise only) and BodyMedia (23/7) for about a week before ditching the HRM. Here's why:

1 hour of Circuit Weight Training:
HRM - 500 to 800 calories burned
Body Media - 180 to 300 calories burned

55 minute Zumba Class:
HRM - 700 to 900 calories burned
Body Media - 400 to 700 calories burned

30 minute C25K (only week 3):
HRM - 280 calories burned
Body Media - 250 calories burned

It was a hard lesson for me to learn. After 8 months of being in this mindset that I was burning...so...much it was very VERY hard to choke down the fact that I was indeed not burning even close to what I thought. But after 8 months of inexplicably gaining weight the more I worked out, it only took me a week to accept that the Body Media was far more accurate when it came to my workout habits and part ways with my HRM. As you can see, the closest the HRM got was during C25K. So if endurance training is your thing, that's the way to go.

Also, HRMs have mostly only been tested on men. Their margin of error on men is <8%. On women, they found it can be off by like, 20% or more.

As for how MFP figures out its calorie formulas: MFP assumes every woman is 26% body-fat. Depending on how off you are from 26%, their calculation on your burns will be off. Google Katch-McArdle formula to find your real BMR. You'll need to know your body-fat % from either a tape-measure online calculator (Heath Central's is pretty good), calipers, bodpod, or DEXA (most people don't have access to the latter stuff though). I don't trust my Tanita body-fat scale, that thing is WAY off (+15%... eek!)

Above is simply how my comment applies to you. Read on only if you want to avoid my further personal mistakes with tracking devices.

***
Now... that said, I also ditched my Body Media after a year of use (I had a tan line and a permanent indent in my arm from wearing it pretty much 23hrs a day). It was very difficult as I was pretty dependent/addicted. I even put together a massive Excel database that tracked more than MFP ever could, breaking down my burns from different types of exercise each week, sodium intake, macros, ToM, etc. In the end... I gained 20lbs in a year, yet "by the math" of calories in vs calories out, I should have *lost* like, 30lbs. I was insanely frustrated. I was burnt... out...

Lessons learned:
1.) I learned the hard way that I was overtraining because I figured, "hey, when it comes to the gym, more is better!" (chasing my 55min Zumba class with 45min of circuit weight training), plus... I only wanted to shower so many times a day. I shot from 22% to 25% body fat in 2 months of this and it was one of the few times I was working out more than I ever had in my entire life, including a 6 year stint in the Marines. Turns out, unless you have a nutritionist's knowledge-base and some serious dedication in your diet, you can't avoid the fact that around the 48-minute mark of exercise your body flips a switch from burning fat (peaked levels of latent testosterone and decreased cortisol levels) to burning muscle (spiking cortisol levels and plummeting latent testosterone levels after this time mark). Now I know that a burn is only a "burn" until I've worked out around 45-50 minutes. I have to wait 3-4hrs if I'd like to work out more in one day because my hormones need to reset.

2.) I wasn't eating totally crappy, but I wasn't perfect either. A calorie isn't really "a calorie is a calorie". Macros are important, and I still haven't got it totally figured out except I shoot for >20% from protein. I need to eat cleaner, and I need to treat processed foods and sodium as the devil. I have A LOT more to learn in the kitchen. But overall, I learned I couldn't out-exercise my eating habits, even if the calorie math made it really look like I could.

KrissyMuree wrote: »

I've consistently used my FT4 for strength training/cardio workouts for years and when I was using MFP before (I should add this is standard DVD ST & cardio, in addition to treadmill, outdoors running/jogging, hiking - not gym ST), I logged exactly what my HRM said and only ate the calories back if I was really hungry. I lost weight consistently. It might be for "steady state cardio" but I have used it for everything and have never had an issue losing weight when following it. I'm so surprised to hear others have had issues!

Because you experienced a coincidence. Asking an HRM to be accurate for something it was NEVER designed for is like asking a calendar to tell you the time.

What people need to remember is that an HRM is a training tool that tells you heart rate. That is the only thing it is designed to do. Everything else is an estimation based on numerous variables. One of those variables is that it assumes you are doing steady state cardio.

That makes sense. What a huge bummer though. After having it for three years and using it on MFP for so long, it's amazing that I had never heard of this. Better late than never I guess.

What would be the best course of action, then? Logging what MFP suggests (or) logging what my HRM suggests, and not eating the calories back? Just following the guided daily caloric intake?

KrissyMuree wrote: »

I've consistently used my FT4 for strength training/cardio workouts for years and when I was using MFP before (I should add this is standard DVD ST & cardio, in addition to treadmill, outdoors running/jogging, hiking - not gym ST), I logged exactly what my HRM said and only ate the calories back if I was really hungry. I lost weight consistently. It might be for "steady state cardio" but I have used it for everything and have never had an issue losing weight when following it. I'm so surprised to hear others have had issues!

I agree with this statement, but I have heard many, including my trainer say you should not count calories from weight/strenght training.

When following the TDEE, say my TDEE is 2,399 - I'd subtract 20%, which would be a total of 1,919, and eat that daily but not log exercise (or simply log but pretend those calories aren't there )? I consistently workout four days a week and since that is factored in ..

brandigyrl81 - I think that's why it worked for me. I didn't eat the calories back, so I wasn't misguided into thinking I was able to justify eating all of this food or anything. I logged it to log it and keep track, and ate 1700 or so a day. It's probably more problematic for people that eat all of their exercise calories back.

brandigyrl81 wrote: »

I, too, have a Polar FT4 and have not had issues with it and I use it for everything from dancing to weight training. I simply just log however many calories my FT4 says I burned under my own exercises, which I've created, and that's it. And I typically don't eat back my exercise calories. As someone else mentioned, I've lost weight just fine using this method. As long as you're accurately tracking all of your food, you shouldn't have any issues.

ksy1969 wrote: »

I know logically why the HRM isn't accurate, but it doesn't matter. I lost over 100lbs by using a Polar FT4 to calculate my caloric burn. Didn't matter whether it was running, walking or lifting. Now, let me clarify, most days I did not eat all my exercise calories. In fact usually only about half, but there were days I did eat them all.

Think about what you both just said. You were using an HRM to calculate calories, but you weren't eating the calories back (or a portion). When you workout you obviously burn something so if you aren't eating them back, of course it looks like the HRM is accurate when in reality, it doesn't even need to be in the conversation for you all since you weren't eating the calories back to begin with.