fat loss vs. muscle gain: when to switch?

A little over a year ago, I made a conscious effort to improve my diet and
start exercising
regularly. I'm 5'7" and at the time, I weighed 225 lbs. I am now at 173
lbs. My exercise regimen consisted almost entirely of cardio - cycling
classes, jogging on the treadmill, going on hikes, etc. I probably could
stand to lose another 10 lbs of fat, most of it in my midsection. However,
my goal is no longer to just be trim. I want to build muscle mass,
particularly in my upper body. I know which exercises to do and how to do
them. I am just wondering *when* to do them. Do I keep doing mostly cardio
till I have lost those last 10 lbs? Or should I be concentrating on
resistance training? And if it's the latter, what should the amount and
composition of my daily calorie intake be?

Thanks in advance for your help.

Nikko,
Congratulations on your transformation from 225 to 173 lbs. I agree
that if you are only ten pounds from where you want to be that lifting
weights would be a good thing to do. You should focus on your body's
composition instead of weight. I gain weight when I work out since
muscle is added. The weight is dense and I sink like a stone when I am
in the water. Since you say you know which exercises to do I assume
that you are planning on doing primarily compound exercises. Lower
body strength is important too and you will get better overall gains if
you do things like squats and deadlifts. I feel like all of my
weightlifting improved (upper and lower body) when I really started to
focus on deadlifting. Start light and methodically work your way up in
the amount you lift. Be careful.

Good Luck,
James