At 5'11" 150# the last thing you need to do is drop 10#. Yikes!!! You are at your ideal weight for your height. 140# would put you underweight. With a low fat diet and 140# you will most likely start burning muscle, which isn't going to help at all.

I'm not sure how much you have lost already, but the "flab" may just be stretched skin from a previous weight. If that is the case then you will have to wait until the skin shrinks.