Increasing lean mass also means a higher metabolism as well of a wonderful variety of other benifits. Those on starvation diets will often just look at the scale trying to push it lower not caring if it's fat or lean mass they are losing. This means as muscle disapears thier metabolism gets lower and they have to eat less and less. For many it also means bone density and organ health (both components of lean mass) are also effected negativly.

While it can be discouraging not seeing the scale move, moitoring the tape measure and using a program like www.mybodycomp.com to help you see body fat disapearing can be very encouraging. I always say no one sees the number on the scale but you, everyone though can see when you're wearing a smaller size of jeans.