That is the Holy Grail of weight loss. How does a person lose more fat than lean muscle ?
It's not an easy question. If you are strength training, continue to strength train. Strength training will help minimize the amount of lean muscle you lose. But here's the catch 22, if you want to lose weight, a certain percentage will still be muscle. How much ? hard to say.
The problem is that in order to increase lean muscle, you can't eat at a deficit. Growing muscle fiber requires a surplus of calories. But, if you're eating at a deficit to lose weight, then your body won't have enough energy to increase muscle. ask any body builder, they'll tell you, if you want to increase muscle, you've got to eat.
What to do ? You have to concentrate on one or the other. Do you want to lose weight OR increase lean muscle ? If you want to lose, then lose weight first. Once you've achieved your desired weight range, then you need to start eating to increase muscle. You really can't do both at the same time.
Check this out, this is what Hugh Jackman had to do to get ripped to play Wolverine. www.huffingtonpost.co.uk/2013/08/07/wolver