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13 Weeks: Stability Is Good. Right?

In the home stretch, and I've made some progress. But it's hard to tell, and I'll tell you why.

by
Charlie Martin

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April 27, 2013 - 2:00 pm
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Week 12 of my second 13 week season: low-carb diet and more exercise, tracking my weight, blood glucose, and body fat. You can follow me at my 13 Weeks Facebook page for daily updates, and you can join Fitocracy (free!) and follow my daily exercise, and maybe even start tracking your own.

You know what’s worse than a day of nonstop meetings? Five days of nonstop meetings. That was my week at the day job, which meant lots of stress and lots of unusual socializing. Still, it wasn’t all bad by any means, and the numbers this week have done well. I lost all of that peculiar bounce and was down to 269 lbs again on Wednesday; this brought the seven-day average down to 270, and as you’ll see in my bodyweight chart I’ve had more and more days under 270 and am still losing weight, albeit slowly.  

In a belated rush of intelligence, I got around to setting up my spreadsheet to compute the standard deviation of both my weight and my glucose. For those of you who aren’t statistics nerds, the standard deviation is a measure of how “wide” a distribution of numbers is, or in other words, how much things vary just randomly. It turns out the standard deviation of my weight is about 2.2 lbs. What that means is that if my weight weren’t changing at all, you would still expect to see it vary outside the range of roughly 268 and 272 pounds 3 days in 10.

The point is: when you’re losing weight slowly, it’s going to be hard to tell you’re losing weight at all.

I’ve got to admit right now I’m puzzled what the best thing to tell people might be if they were doing their own program. We all know that weight shouldn’t matter, but it does. A lot of people have suggested just weighing once a week, but that doesn’t actually help much, as you can see in the table. The standard deviation tells us that you have to lose about 5 lbs before you can have much confidence it’s not just random variation for a single measurement.

What you can do, though, is look at the graph:

Weight so far in this 13 week experiment.

On the chart you can see that I’m spending more days under 270 than I was before — something between 20 and 25 percent of the time in the last half of the 13 week experiment.

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