Technically 170, at 5’11” is not skinny. In fact that is a healthy weight for the height. Believe it or not people who are 5’11 and 200lbs are considered obese/fat by doctors, unless of course that 200lbs is mostly muscle.
Realisticly that just doesn't work. I'm 5'11 and swim a mile every day. I eat a very healthy diet. The lowest I can get to and maintain enough energy to work out is 188-90. (which is what I pretty much stay at) Most would consider me very lean. To get down to 170 I would have to get scrawny. I know what those USDA regs. say but they are crazy in the real world. To call a 5'll" 200 lb. person obese is delusional.