Questions about body fat

How was the measurement taken? And did you use the same method/circumstances/environment as last time?

I ask because I was measured on a bioelectric impedance scale (barefoot with the handles for my thumbs) in January, and I showed 11.5%. Then I received my DEXA results (the most accurate measure), which were taken the same day, and I was 15.9%. Then in February, I did the scale again, and it showed 10.1%. (Muscle mass is good, btw, so no cause for alarm about the low percentages--from my trainer or doctor.) My trainer wants me to take the scale measurement weekly. (It's just out for anyone to use.) So I'll go by that in terms of trends, but I'm not going to rely on its accuracy too much.

Your best bet is to just consult with your trainer. Years ago, I tried doing similar math that you're thinking--like how much fat is left, how much would be left at my goal weight, etc. I think I ended up with a mental block about what was possible.

I think you could be losing muscle mass but getting stronger. There are different types of muscle building--one is about getting bigger, and the other is about getting stronger. http://en.wikipedia.org/wiki/Muscle_hypertrophy

1) Basically in the last 3 months I have lost apparently body fat and muscle. I am lifting heavier and heavier weights as I get stronger and the previous measurer input my height as 4 inches taller so I don't know if that threw off some of the calculations. But my real question is: can I be getting stronger and still be losing muscle?

Yes - you can get quite a bit stronger while maintaining and even losing some muscle mass. You brain & nervous systems learns how to better use your muscles.

2) When I calculate how much of my body is fat according to the percentage does the remainder that is not fat mean that is as low of a weight as I can go? Should I structure my goal weight around that?

No. Men and women have limits on how much fat they need to maintain - called essential body fat. For men it is somewhere around 2-4% and for women somewhere around 11 - 13% (please google - that is from memory). Below that and bad things start to happen. And realistically, the leanest, competition-ready physique competitors are generally just above these levels, and then for only short periods of time around competition day. In my reading, I get a sense that it is pretty challenging for men not fully committed to body fat maintenance to stay in the single digits, and for women, to stay below 17% or so.

Hope that helps. Oh, and write down your questions and bring your notes to your trainer next week.