Well according to the bmi, your "normal" weight would be less than 160, but a lot of people dont like the bmi because it doesnt take body type or muscle/fat ratio into account. But I still think its a good point of reference. http://www.cdc.gov/nccdphp/dnpa/bmi/calc-bmi.htm
Personally, I am 5'8 and my goal is 147 - 150. I still have several lbs to lose before I get there, but that was the weight that I use to be and I looked really good then.
This time, I workout alot more than I use to with weights, so that may be a little low nowadays. I guess I will just have to see how I look and feel as I get closer. At 5'7, depending if you want to be skinny or slim and your bodyfat percentage is, you would probably look nice somewhere between 140 - 150. IMHO Heck for all I know, you could look perfect now.
I am 5'7" also. When I started losing weight I was about 160. I just wasn't comfortable. Now after about 2 1/2 months....and a little help from Phentermine....I am at 137. I am more comfortable at this weight. I ain't trying to be a toothpick. I think the other responders are right though...alot depends on body type. Like me, any weight I gain goes straight between the knees and ribs. ( thighs and butt ) But when I lose weight the first place it comes off is the chest arems and face. Sooooo unfair. Good luck with whatever you decide. When you are at a comfortable weight for yourself...you'll know.
This is always a hard subject for me. I am 5'3. Several years ago I weighed in at 170 and was a size 14-16. I got down to 115 and that was way too thin, moved to 125 and was a size 8... was not using weights. I weight train now, weigh in at 140 and I am a size 4/6... so it is really weird. I am smaller now at 140 than I was at 125, but it is all due to my muscle mass. So see where the confusion comes in! LOL!!!! You have to find a happy weight for yourself!!! I hate weighing, only because the scales don't tell you the whole story... measure rather than weigh and I think you will find the answers there Good luck!
First of all, don't pay attention to BMI or ideal weight charts. These are generalizations that only insurance companies take seriously. BMI does not take into account how much muscle you have and ideal weight doesn't factor it in either or the fact that people have different frames. I'm actually below what's considered my ideal weight and yet I still have a slight belly and love handles. Focus instead on your body fat percentage and on what you see in the mirror. Those are better indicators than BMI or ideal weight.