Electronic devices to measure BF% are worthless. They are easily fooled by water retention, which can swing ten pounds in either direction for some people.
The best ERE tools for measuring body fat percentage are this :
1) A mirror
2) A bathroom scale
3) A tape measure (I use the notches on my belt)
4) If you want to get fancy, get a body fat calipers. Reusable, few moving parts, cheap, and precise. You can't even get consistent results with a DEXA scan, a $150 glorified bathroom scale will only make your wallet lighter. The body fat calipers may not be 100% accurate, but it is extremely precise. You will know if you're losing fat with the calipers. Take a couple measurements and average them out. I bought the Accu-Measure Fitness 3000 Personal Body Fat .
Basically, check where you're at at regular intervals. Once a month I'll usually see where my belt notch is at, weigh myself, and take a picture of myself in the mirror.
If the scale isn't moving, but you look leaner/more defined in the mirror, then keep doing whatever you're doing. You're likely building muscle. Lean and muscular is attractive, healthy, and functional for everyone.
If the scale goes up, but your belt (waist measurement) stays the same, you're building muscle.
If the scale stays the same, but your waist measurement goes down, you're dropping body fat.
If the scale goes up along with your waist measurement, it's time to reevaluate your goals. Unless your strength levels are going through the roof, you're likely overeating.