JD_Johannes’s BodyBlog

I’ve gotten a lot of questions about diet from people who are using formulas to determine their caloric intake.  In my opinion most of those formulas are not very useful.

Let me illustrate this with a common formula for determining resting metabolic rate.

RMR = 9.99(WEIGHT in Kilograms) + 6.25(HEIGHT in centimeters) - 4.92(AGE in years) + 166(GENDER)-161

If I were to plug in my specific data, the formula would look like this:

RMR = 9.99(94) + 6.25(177.8) - 4.92(36) + 166(1)-161

(*Note, men enter “1” for their gender, women enter “0”)

So if I calculate it out my RMR is 1,879 calories.

Ok.  Now, how on earth was this formula derived?

Most likely a group of researchers had a large group of test subjects come in to a lab.  In the lab they probably used a sealed chamber to measure oxygen exchange rates to determine metabolic rate.

Then they took the information about the test subjects—weight, height, age, gender—and started working on a formula that would prove accurate enough 68% of the time.  In other words, a formula that fit nicely with the bell curve distribution.

But as we see from the bell curve, people, even when near the middle of the curve, are still scattered all over.

The RMR formula above is accurate but not exact.  The formula could easily be off by 5% on me which would equal about 100 calories.  If I eat 100 more calories than I burn over the course of 35 days I will have gained a pound of fat.

This why the internet message boards are clogged with questions from people who are, by the formula, eating the correct amount of calories to lose fat or gain muscle, but are getting no results.

Each person is a little bit different and no bell curve derived formula can predict anything about them with precision.

(To see the folly of bell curves in action one only has to look at the meltdown of the financial industry which relied on bell curve distribution models to manage risk.  A bunch of really smart people using customized formulae still got it very wrong.)

To lose fat one needs to eat with precision and determine with precision the macro-nutrients and caloric intake that will allow them to lose fat.

To do that you need to conduct controlled experiments on yourself and track the results with precision.

In the Chapters covering Phase II of the Fit for Combat system, Nita and I explain that the best way to discover the eating plan that works best for you is to weigh and measure all your food to the gram then make gradual adjustments and track the results.

Over the course of a few months this will lead you to the eating plan that works specifically for you.

And rather than rely on a bell curve based formula to determine your metabolic rate, why not track the changes in your metabolism using a quantifiable number with a thermometer?  Yes, a simple digital thermometer.

Lets go back to the metabolic formula for a moment.

RMR = 9.99(WEIGHT in Kilograms) + 6.25(HEIGHT in centimeters) - 4.92(AGE in years) + 166(GENDER)-161

What are the constants and variables in this formula?  Your gender is a constant.  Your height, depending on your age is a constant.  The age changes once a year.  But your weight is a variable.

Your weight can change through a gain or loss of muscle and/or fat.  Moreover, the formula only asks for weight making no real distinction between lean tissue or fat.  But muscle is one of key factors in determining metabolic rate.

Researchers from Aberdeen University in Scotland found that 63% of the time, differences in metabolic rate between tested individuals were determined by muscle mass, 6% of the differences were determined by fat mass and 26% of the time they had no idea what caused the variations.

The results of the study, published in the November 2005 edition of the American Journal of Clinical Nutrition, shed light on the flaws of the standard Resting Metabolic Rate formula.

A formula that does not account for muscle mass will be incorrect.  Even more important is the conclusion that 26% of the time, there are variables to metabolic rate that cannot be determined.

If you are relying on a generic formula to guide your eating plan, you could be very, very frustrated.

Another shortcoming of the formula is that it does not account for is your body’s reaction to caloric input, the Krebs cycle, and how it will adapt.

The body’s metabolism will adjust up and down to caloric input.  It does not speed up much with increased calorie consumption but definitely will slow down from calorie restriction.  When a person is dieting to lose fat, the metabolism will adapt to the lower calories creating a diet plateau.

Most people use a bathroom scale to determine whether they are gaining or losing weight, but even if you weigh yourself every day right after you wake up, there are still variables.

Body fat calipers to gauge fat thickness in millimeters are great to determine fat loss, but the daily changes are too small to make rapid diet adjustments to keep ahead of the Krebs cycle.

A thermometer though provides a daily reading that can be tracked to determine if the metabolism is slowing down or speeding up.

Keeping a thermometer on your nightstand and taking your temperature right after you wake up will give you a precise measurement to a tenth decimal of your metabolism.  No, it will not be able to tell you how many calories you should eat, but the trend will tell you if your metabolism is adjusting.  And the changes you can detect from the thermometer are detectable faster than with a scale or calipers.

With the scale and calipers, you only know the metabolism has adjusted when you level off or even worse, begin to gain.

A slight drop in waking body temperature over the course of a few days indicates a metabolic slow down way before the plateau is actually reached, allowing you to make adjustments and stay ahead of your metabolism.

The thermometer, when combined with a food scale to ensure precise eating, body fat calipers and a scale will keep you on track to adjust your eating specifically for you.

You could rely on formula, but they are often like the Body Mass Index calculations.  The BMI calculations say that despite my visible abs, I am obese.

You will have greater success if you ignore the bell curve derived formulas and focus on using quantifiable measurements to dial on what works specifically for you.

Workout advise and formulas derived for the “average” only work if you are among the small percentage of people who are precisely average.  In reality, only three percent or less of the population is precisely average.

For the other 97% of us, it is best to use measurements on ourselves and take the time to experiment to find what works specifically for us.

This entry was posted on Monday, June 1st, 2009 at 1:34 pm and is filed under Training. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.