Friday, January 9, 2015

Calories Burned and Other Witchcraft and Wizardry

I've learned a lot in the 2 weeks that I've been using My Fitness Pal.

I've learned that I was eating way too much food and that what I thought was a serving is actually enough to feed both Doug and I.

I learned that, if I eat healthy balanced meals and snacks, I can eat a more reasonable amount without feeling any more hungry. In fact the only difference is that I don't feel that heavy full feeling that I felt after most meals.

I've learned that eating 3 squares of chocolate as a treat after dinner tastes more delicious than eating 6 of them. I think our taste buds turn down a notch or two after the first few bites of food so I'm learning to take a bit of something, eat it, enjoy it, and then decided if I need a bit more.

In the last two days, I've also learned that calculating the amount of calories burned during exercise is less of a science and more of a combination of witchcraft and ruby-slippered heel clicking.

Calories burned

Since day one, I had been entering my runs and my bike rides into My Fitness Pal and it would immediately spit out a number of calories burned which it then added to my daily calorie total. All I had to do was pick the activity from their list, enter the time I spent doing it and voilĂ !

But then I tried to enter my CoreFit class on Tuesday night and the wheels fell off the cart. CoreFit is not a cardio exercise and it's not a strength exercise. It's both. And it's not on the list of activities that My Fitness Pal has for us to pick from. So I started looking at how calories burned are actually calculated and one website brought me to another one and soon enough I realized that it's just plain overwhelming to try to do anything other than estimate.

I learned that having a sense of my average heart rate over the course of the activity is helpful so, for research purposes, I put on my heart rate monitor for my Thursday morning bike ride. My average heart rate over the 51-minute ride turned out to be 121 beats per minute (bpm).

I entered the workout into My Fitness Pal (without the heart rate because you can't actually put that in) and it said I burned 498 calories.

I uploaded the workout into Training Peaks (with heart rate) and it said that I burned 602 calories.

I then tried plugging my age, weight, heart rate and time spent cycling into a formula that I found referenced at a variety of online sources and it said that I burned 333 calories.

One workout, three very different numbers.

For fun, I decided to wear my heart rate monitor to Tabata class on Thursday night. It's another workout that isn't easily plugged into My Fitness Pal. After class I uploaded the data into Training Peaks and learned that my max heart rate was 152bpm and my average was 116bpm.

Training Peaks said that my calorie burn over the 42 minute class was 319.
My formula said that it was 252.

Those two were a little closer this time.

I'll be wearing my heart rate monitor on Saturday's run and am very interested to see what that tells me.

My guess is that I will have to take any number given with a grain of salt, eat more food on days when I exercise more but not worry too much about the details.
P.S. the formula I was using for anyone who is interested is:

C = [(A x 0.074) - (W x 0.05741) + (H x 0.4472) - 20.4022)} x T / 4.184

C = calories burned
A = age
W = weight (in pounds)
H = average heart rate in beats per minute
T = time in minutes

Note: this formula was for females. There is a slightly different one for males that you can easily find by Googling if you want it.

P.P.S. I also learned that I apparently have a crazy low resting heart rate. I was walking around the house and my heart rate hovered around 65-75. I sat down and, within 15 seconds, was down to 48 beats per minute. I Googled that too and discovered that I'm supposed to tell my doctor if my heart rate is consistently below 60. So I sighed, stopped Googling and went to Tabata.

1 comment:

  1. I've never gotten consistent numbers from everything that tries to compute calories--so I'm skeptical of most--although I tend to believe the calculations more from the apps that connect directly to the heart rate monitor. So I believe my Garmin and Training Peaks more and formulas and tables less. But that's just me.

    BTW, I started using MyFitnessPal yesterday to nudge me back toward my racing/summer weight. It's pretty cool. And what do you know... you can add insulin as a "food" in your diary. I'm trying to figure out what my bolus ratios really should be, so I think this is pretty cool.