Gas station without pumps

2015 December 31

Twelfth weight progress report (one year)

Filed under: Uncategorized — gasstationwithoutpumps @ 15:57
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This post continues the series of weight progress reports from the previous one. This report marks one year from my New Year’s resolution at the beginning of 2015.  At the beginning of the year, I said I wanted to drop my weight by 10–15 pounds, by which I meant a target weight of 160–165 lbs 0r a BMI of 22.5–23 kg/m2.  During the course of the year, I re-defined my goal to a target weight of 155–160 lbs or a BMI of 21.6–22.4 kg/m2.  I reached that target range in April, and pretty much stayed there until the end of September, when I had a sudden spike in weight that took me about a month to correct.  November and December were not good for my weight, which has drifted up to hover around 161 lbs.

2015 weight record, showing successful weight loss followed by almost successful maintenance.

2015 weight record, showing successful weight loss followed by almost successful maintenance.

My weight has drifted outside my target range several times, and the holidays have been particularly bad for keeping it in bounds. I’ve adjusted my target weight to gradually relax the upper limit, to allow it to increase at 0.6 lbs a year, which would allow me to drift up t0 178 lbs over 30 years.  But I’m currently over even my relaxed limit, so I’ll have to go back to my  strict raw-fruits-and-vegetables-for-lunch diet, which I have not been keeping to very well lately.

My Body Adiposity Index now estimates my body  fat at 23.4%, while the estimate from BMI is 24.8%.  According to some calibration studies on people in Louisiana, neither estimate is particularly accurate—by that study, the correct value should be around 18±5%.

My exercise for December is way down also (only 2.48 miles/day of bicycling, down from 4.28 miles/day in November) and my total mileage for 2015 is only 1479.4 miles.  I was going to do some cycling with my son over break, but he got some mild gastrointestinal bug, and I’ve been a bit under the weather also, so we never got around to doing the bike rides we had planned. Even the short ride we attempted to UCSC to film a short video on oscilloscope usage got cancelled when he threw up halfway up the hill (the first symptom of the gastrointestinal bug, other than fatigue).



2011 March 9

BAI: A Better Index of Body Adiposity

Filed under: Uncategorized — gasstationwithoutpumps @ 09:09
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In the journal Obesity, there is an article, A Better Index of Body Adiposity, suggesting a new way to estimate how fat people are from simple measurements.  The authors hope to replace the body mass index with an equally simple index that does not need so many corrections for race and sex.

The new measure is indeed simple \mbox{BAI} = p/h^{1.5} - 18 , where p is the hip circumference in cm and h is the height in meters.  The 18 is there to make the index be approximately the %fat for the individual, which was directly measured in the calibration sample of 1700 people using dual-energy X-ray absorptiometry (DXA).

I tried applying this measure to myself (104 cm hips, 1.8m tall), and got and estimate of 25% body fat. Hips are measured “at the level of the maximum extension of the buttocks posteriorly in a horizontal plane.”  Based on the calibration sample, this puts me in the range where BAI does a good job of estimating %fat.  The BAI measure tends to overestimate %fat at both the low end and the high end of the measurements, but for most of the calibration sample it was within about ±5.

My BMI is about 25.1–25.8. Using the formula
Adult body fat % = (1.20 x BMI) + (0.23 x Age) – (10.8 x gender) – 5.4
from Wikipedia’s Body fat percentage, I get an estimate of 26.8–27.6% body fat.  I think I like the BAI measure better, though I have no idea which is more accurate.  Both measures put me at the low end of the overweight range, which matches my self  image.

Of course, there have not been any studies yet to show whether BAI has a better diagnostic value than BMI, but it doesn’t seem to have different scales for males and females, the way that BMI does, so it is likely to be more useful.

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