Bod Pod

Yesterday I got into the Bod Pod at the U to have my body composition analyzed. Wearing a sports bra and bike shorts and a swim cap thingie to hold my hair tightly, I sat in the machine as it measured the air I was displacing and calculated my density. I was surprised to find out that my body fat is only 16.8% - less than 19% is "very lean" for a woman in her 30s. They recommend that a woman have 12-15% fat minimum to be healthy. I had done a hand-held impedance measurement back in April, and it said 22.8%. However, I have lost 5 lbs since then, and the hand-held units are not nearly as accurate as the Bod Pod.

I'm wondering what to make of this measurement. Was it off because my tight biking shorts held in my flabbiest parts (hips & thighs)? If it was, that would make some sense to me. If not, would it be foolish for me to still take off another 5 lbs to see how it impacts my racewalking performance? I think I am going to proceed with my original plan, which is to lose 5 more lbs and see how I do. That would put me at 140 lb at 5'8", which should be a perfectly healthy weight (BMI is still over 20 - which is normal, not too thin).