Evaluating Daily Caloric Needs - (This contains math!)

It's been 3 months since joining MFP. Since joining I've really learned alot. I've been through the whole, "do I eat my exercise calories or not" and understand the math that's going on behind the scenes.

MFP uses the MD Mifflin / ST Jeor method for determining BMR, which is one of three available formulas for determining BMR. Harris Benedict has been marked as overestimating BMR, especially in overweight subjects. The third is Katch McArdle, which I'd never heard of until recently. Supposedly it's more accurate if you know you're body fat percentage.

Katch McArdle states that BMR = 370 + ( 21.6 * Lean Body Mass in kg )

In order to solve the equation we need to know what our Lean Body Mass is. I set out to determine this today, by means more accurate than any online calculator or equation (James / Thume). I bought a set of calipers to do a self test and had my body fat analyzed by an Omron Body Fat Analyzer (one of the ones you hold with both hands out in front of you). Keeping in mind I'm not a pro in doing the caliper test, especially on myself, I did my research, watched some videos and read the instructions so I'm sure I was "fairly" accurate in my results.

Accu - Measure Calipers - 24.5% (+/- 1%)
Omron BF Analyzer - 21.3% (+/- 3%)

(Note: I'm still not satisfied with the results of the test. My buddy took the test after I did, we changed the information to reflect his statistics and his BF% was analyzed as 24.9%. My buddy is Marine, Army Ranger, has great Genetics and in excellent shape. Much more defined than I am and works out 2x per day, most days)

I took the average of the two measurements and figured my LBM to be 22.9%

The equation for solving for Lean Body Mass is
LBM =(Body weight in kg * ( 100 - Body Fat Percentage ) ) / 100
LBM= ( 108.64 * ( 100 - 22.9 ) ) / 100
LBM= 83.76 kg or about 184.27 lbs

Back to Katch McArdle....

BMR = 370 + ( 21.6 * Lean Body Mass in kg )
BMR = 370 + ( 21.6 * 83.76 )
BMR = 2179

This figure is only slightly off of MFP's MD Mifflin figure of 2122 calories. Negligible.

Now I need to account for my activity level. I exercise 4-5 days per week but otherwise my activity level is taking care of a household, office work and I travel about the country 120 - 180 days per year. My workouts burn anywhere from 500 - 1200 calories, as monitored with a HRM. To simplify having to have a different caloric intake daily based on if it's a workout day or a rest day, I assumed I am moderately active, multiplying my BMR by 1.5.

2179 * 1.5 = 3269 calories <

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Maintenance calories

To lose 1.5lbs per week I need to subtract 750 calories.

3269 - 750 = 2519 calories


Question - By taking a more simplified approach, will spreading the calories out over the week slow my progress? ie. the days which are rest, I'm essentially consuming 'some' exercise calories.

Up until now I've been setting MFP to Sedentary to account for my daily activities other than exercise, be it light office duty, showering, talking, household duties etc. and then adding in my exercise calories based off of what my HRM records during my workouts. This has been working for me, but as I'm beginning to better understand the process, I want to further simplify it all so at some point, I'm not necessarily having to wear a HRM. Eventually one day when my phone breaks or MFP implodes, I want to be able to do this on my own and not be forced to use the MFP security blanket, albeit cozy.