Starting on May 16th, I recorded weight and body fat percentage as measured by an Omron HBF-500 on a semi-consistent basis. At the time, I wasn’t planning on writing about it so I wasn’t diligent about recording the measurements every day. But, because of how the numbers turned out, I want to use them to show you something. Keep in mind I wasn’t trying to lose fat or gain muscle or do anything specific, really. I was just living.

5/16 – 168.4 @ 15.2%

5/17 – 170.0 @ 15.6%

5/18 – 170.6 @16.7%

5/20 – 169.8 @ 16.3%

5/23 – 167.2 @ 15.3%

5/24 – 166.0 @ 16.9%

5/25 – 165.2 @ 16.7%

5/26 – 163.6 @ 16.5%

5/31 – 168.6 @ 14.9%

6/2 – 166.0 @ 17.2%

6/4 – 165.0 @ 16.5%

6/6 – 167.8 @ 14.4%

6/8 – 164.0 @ 13.6%

6/9 – 165.2 @ 15.5%

6/10 – 165.2 @ 15.6%

6/13 – 166.2 @ 13.7%


Let’s look at the most obvious “jump” between measurements from 5/26 – 5/31.  These measurements were before & after a weekend camping trip. I consumed a lot of “trail mix” (peanuts, raisins and m&ms), hot dogs w/ buns, s’mores w/ Hawaiian Rolls (something a friend and I discovered while *ahem* chemically altered) and alcohol. According to the scale I gained 5 lbs (totally believable), lost 2 lbs of fat and gained 7 lbs of muscle (not believable). Unless there is something in the water near Wood’s Canyon Lake, this is an error.

This isn’t listed above, but I saw similar results after a night of knocking back a few – I dropped 4% from one day to the next.  I dropped 5% over last weekend after a two-day dodgeball tournament.

If you’re in the process of losing weight, use the scale to monitor your progress but don’t measure body fat every day. Once a month is probably sufficient and make sure you are consistent about what time of day you’re measuring.The numbers I listed above were all morning measurements, after voiding, with no clothes and they still varied quite a bit. You can see I often gained or lost a pound between days. For body fat, pick a day of the week when you’re most consistent the days prior – like Thursday. Most people don’t do anything crazy Monday-Wednesday so Thursday morning is a safe bet.

So once again, what’s the point? The point is that at-home scales are going to screw-up body fat measurements if you use them too frequently, especially if you’re not being incredibly consistent with your lifestyle habits. This is going to be a complete mind-game if you get sucked into it. You’ll think you’re ripped one day and a fat tub-o-goo the next. Don’t get sucked in.

A Month of Weight and Body Fat Measurements
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