Metabolic profile assessment

Question
Hi Ms. McLauglin,

I just had a metabolic profile assessment done (referred by my campus health center), in which I breathed into a machine for about 30 minutes, and then got results that gave me calorie utilization and substrate utilization (I think the nutritionist said it was measuring the Respiratory Quotient or something of the sort). However, after going over my results- I am still a bit confused so I was wondering if you could help me interpet them. The nutritionist told me that the tests revealed I burned 1100 calories a day (25% under the 1400 I am supposed to burn for my weight/height). She also said that my protein turnover rate was off the charts- clearly indicating a metabolism that is off balance. Currently, I have a very low caloric intake due to years of dieting- around 600-700 calories a day, on average. My nutritionist said that my caloric expediture number (1100) depended both on the number of calories I would burn as a completely sedentary person PLUS the number of calories I burn from being active (walking around campus, exercising 4X a week). Is this correct? After we calculated a rough estimate of the calories I burn due to physical activity (also around 600 per day), this would give me a BMR or RMR of around 600. I am confused only because I did not think calories burned through exercise, only how many your body needs to perform day to day functions (I did fast 12 hours prior to this test). Are you familiar at all with these measurements? And, if so, does the calculation of 1100 equal my metabolic rate inclusive or exclusive of calories burned during physical activity?

Thank you, hope this wasn't too confusing :)

Alexandra

Answer
Hi Alexandra,

From what you've told me, it sounds like you had an indirect calorimetry test. This measures 2 things:

1. A measure of energy expenditure as reflected by the resting energy expenditure (REE)
2. A measure of substrate (e.g protein) utilization as reflected in the respiratory quotient (RQ)

Resting Energy Expenditure (REE) accounts for 75 % - 95 % of total energy expenditure(the remaining 5-25 % of total calorie expenditure is mostly from physical activity).

REE varies somewhat from day to day and during different parts of the day,and also due to illness.

Based on the information you've given me, it sounds like your REE is 1100 calories per day. This means that you would add additional calories to that for any physical activity (so if you do 600 calories worth of activity, your daily caloric needs would be 1700 calories). That would be the number of calories you need to maintain your current weight. If you are trying to lose weight you would need to take in less calories.

One thing that can significantly affect your REE is your total lean body mass (muscle mass). Many people who have been chronic dieters have lost significant muscle mass over the years, which just makes it harder to lose weight (muscle mass burns a significant number of calories, even at rest). Conversely, you can increase your REE by building muscle mass through strength training. I would recommend that, as long as your physical health permits, you add some strength training to your exercise program, 2-3 times per week. Two good resources to get you started are _Sculpt Your Body with Balls and Bands_ by Denise Austin and _Weight Training for Dummies_ by Suzanne Schlosberg and Liz Neporent.

Hope that helps!

Karen
www.getfitwithkaren.com  

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