Metabolic Testing, Part Two: RMR

As I discussed in my previous post about the metabolic assessment I did last week, there are two tests: Resting Metabolic Rate (RMR) and Exercise Metabolic Assessment (EMA).  I'll talk about the results from my RMR test today.

When I got there, Stephanie (owner of In the Zone) took some basic data (age, weight, height, etc.) and plugged it into her computer program.  Then she had me put on a heart rate monitor, and she also put a mask on my face, making sure it fit pretty tightly.  I'm glad I couldn't see myself; I'm pretty sure I looked like Hannibal Lecter.  The mask measured the amount of oxygen in the air I exhaled to calculate how much of it my body was consuming.  Since this test measures your body at rest, it's important to be very relaxed (part of which means fasting for 12 hours prior to the test so your metabolism is at rest).  Stephanie turned off the lights and left the room, encouraging me to just chill out for the approximately 15 minutes the test would take.

The test results are immediate, and there was some good news and some bad news.  The good news: my resting heart rate averaged 49 beats per minute (the lower, the better!).  The other good news: based on the amount of oxygen and carbon dioxide I exhaled, the results showed that I am mostly aerobic at rest - 80%, in fact.  That means that my body uses mostly stored fat for fuel when I'm at rest, instead of just burning carbs and breaking down muscle.  The low heart rate and the aerobic respiration are both a result of the aerobic training I have done.


The bad news: my body only burns 1,302 calories at rest, which she confirmed is pretty low.  When she said that, I really thought I was going to cry.  When I only eat 1,300 calories, I feel insane.  I get cranky with my family and lack the energy to focus on anything.  However, Stephanie immediately reassured me that was the absolute lowest my body burns, without moving at all during the day.  She said that the RMR number is what doctors would use to calculate how much to give a person in a coma; it is NOT what I should be eating daily.  She then calculated for lifestyle factors.  Being a teacher and a mom, I'm up and about a lot during the day.  I definitely move more than someone with a desk job, but I move way less than a construction worker or a dance instructor, for example.  So, we entered "light" for the lifestyle factors (the second lowest category), which added another 521 calories, bringing the grand total for the day to 1,823 calories.  Stephanie said to stick to that 1,800 calories no matter what. 


After leaving, I had a moment of panic.  In order to lose just a pound per week, I'd need to cut out 3,500 calories.  If I am eating 1,800 calories per day, I'll maintain my weight.  Cutting out 3,500 calories per week brings me back down to that evil number of 1,300 calories per day.  Of course, exercise will take care of some of those calories, so I'll be able to eat more.  But what about rest days?  And what if I don't exercise enough to burn 500 calories?  I emailed Stephanie and asked what I should do on rest days.  Here was her response: "I think you should NOT eat under 1800 calories per day, even on rest days.  That is my recommendation for health and sustainable weight loss.  1800 cals is what you burn per day without exercise.  If you do eat under that amount on an occasional day or so, it is not catastrophic...just not sustainable.  Hope that helps." 


I told her I was going to print that and frame it!  I'm still really nervous I'm going to gain all the weight back (which I may have done when I was in California - I'm still too scared to get on the scale!), but I'm willing to give this a chance.


I highly recommend getting this test done.  It was awesome to have concrete information just about me!!