MedGem and Estimating Your BMR
The BMR (Basal Metabolic Rate) or RMR (Resting Metabolic Rate) is the number of calories you would burn if you were to lie motionless all day. Rebecca (my last personal trainer years ago) suggested that if you eat your BMR calories every day, everything you do, from walking down a hallway to scratching your eyebrow will burn fat. While this is a bit of an oversimplification, the approach is valid.

There are a few common ways to estimate BMR. The Harris-Benedict equation is nearly 100 years old, and uses height and weight to approximate BMR/RMR. Katch McArdle is an improvement on the older formula because it considers lean body mass instead of just body weight. The MedGem/BodyGem measures actual oxygen consumption at rest over a period of 10-15 minutes to determine calorie burn to a high level of precision without the need for height or weight.

The advantage that the MedGem has over the estimation formulas is its ability to measure your burn rate right now. The formulas cannot account for metabolic slowdown from excessive cardo or heavy dieting. With the MedGem, you can tell right away if you have started into a metabolic slide.

So, how does MedGem stack up against H/B and K/M in a non-fasted state?

My Measurements
H-B: 2209
K-M: 2068
MedGem: 2380

There is a 300 calorie difference between K/M and the MedGem. Interestingly enough, the harris benedict equasion, while using fewer variables, is closer to my actual BMR. (Assuming the MedGem is as accurate as the research claims http://www.metabolismmatters.com/documents/medgem_validation.pdf)

The Importance of Accuracy (May Surprise You)
This blog sounds like it is running down the rosy path to highly recommending the purchase of this ridiculously expensive machine… but here is a reality check:

The MedGem may be highly accurate, but other variables make its accuracy essentially worthless: 1) how many usable calories are in the food that I eat, and 2) how many calories I really burn over the course of a day.

Calories Consumed
As a scientific empiricist, I like to attach measurable standards to the things that I do so I can repeat and improve the results. Since the turn of the 20th century, the calorie has been a popular measurement for consumption, but it falls down as a standard in one important respect: In the body, a consumed calorie does not translate directly to usable energy.

Oxygen Bomb
Have you ever wondered where the calorie numbers come from on the packaged foods? They throw a serving of the food in a device called an oxygen bomb calorimeter which burns food to ash and measures the heat produced. This is a good, repeatable method for determining the energy in food, but the body doesn’t derive energy from food the same way that the oxygen bomb does.

Useful Energy
The body uses energy to digest food; and some foods require more energy to process than others. Protein requires more energy to burn than sugar, for example.
(Good Article on Calorie Counting: http://www.webmd.com/diet/features/dos-donts-counting-calories)

So, does this mean we should calculate the net usable calories on foods so we can be more accurate in our estimation? It might be an interesting exercise, but again, the point of knowing net usable calories for the sake of accuracy is rendered moot by the fact that we will never know precisely how many calories we burn.

Calories Burned
I have this handy Polar watch that estimates how many calories I burn when I’m working out. I have found that it “feels” accurate for cardio work, but it completely underestimates burn during weight training. (Based on my hunger levels throughout the day.) The reason for the discrepancy is because heart rate, weight and height do not translate directly to exertion, especially in the case of short term exertion. Explosive movements require a lot more energy than the moderate expenditure of sustained cardio work over the same period.

The point of this is that trying to chase down calories eaten versus calories burned is a futile exercise. You cannot tie results directly to calories consumed/calories burned because it is impossible to measure this to the required degree of accuracy.

The Useful Measuring Tools
…

I’m afraid I’ve run out of gas for tonight, but I really think I’ve hit on something here. I’d like to isolate the truly useful planning and feedback tools. Here is a little brainstorm activity (don't expect the following to make sense -- I'm just free-forming ideas)

* Documenting consumption and activity is important, the more you plan, the easier it is to track your foods.

* Create two full-day meal plans with the same number of calories and same basic macroutrient composition. Eat these meals consistently throughout the week to eliminate the changing diet variable.

* The real value in the bodygem isn't in the BMR calorie count that it reports, rather its ability to report a metabolic slowdown. But you don't need a machine to tell you that this is happening - just check the mirror

* Really get in touch with how you feel and use that to gauge your fat loss progress. Caloric deficit tends to create irritibility and depression. Caloric surplus tends to create euphoria and hormone function (e,g, libido).

* Document what you do, and pay attention to the results. If you start to see real progress, continue doing what youre doing until you stop making progress.