has your aerobic activity increased of late (last six months or so)?
for years (many years) I weighed between 190-200 lbs; I was relatively active and was lifting 3-4 times a week, but no real consistent aerobic activity-running/biking/etc
roughly five years ago I started running and my weight started dropping- it ended up right in the 175-180 range, so a pretty big drop
I would invest in a scale- it would at least let you point to how much weight is being dropped; I don't use mine much, but get it on it once a week or so just to check
