No.
exercise at a 65% vo2max
There is no any problem or abnormality for a 5'6 male to weigh 160 pounds.
5'9
You're within a healthy weight range, so you don't need to lose any more, but in order to maintain a healthy weight, don't fall below a weight of 112 pounds.
112 pounds is a good weight for a 5' 6" 18-year old male. They should not lose much more weight than this.
16stone
80lbs
It is hard to answer this question without a little more information, such as: Are you male or Female? How tall are you? What is your activity level (sedentary, mildly active, very active, etc.) What is your weight loss goal? Over what time period do you want to achieve you weight loss goal? How many calories do you eat, on average, at the moment? If you can supply this information (or as much as possible) I will try and give you a better answer. Cheers
This depends on what your weight is now. But, it is important to have body fat. Women have more fat than male. Losing weight isn't always good, it is important you are only losing the fat.
200
185