I'm 19 years old, I weigh 165 and I'm 5'5, how much pounds do I n!

A good weight for you is between 125 - 135 pounds......depending on your bone structure
Just eat healthy, exercise and remember....there are no quick fix weight lose plans.....If you lose too quickly, you will gain it all back plus a bit more.....Get off the diet treadmill
Your body will react according to how you treat it....
First it will go into "protection" mode and make sure you don't starve....That is why in the beginning people lose weight quickly and then suddenly have very little weight lose...Finally will adjust to regular intakes of food...Also remember...All the fat cells that your body has acquired will never disappear.....So anyone who has been overweight, most of their life, will gain more quickly than someone who has been of normal weight........Use some common sense and see a Doctor or Dietitian who can advise you......This is a lifestyle, not a one time diet to lose weight..Good Luck :-))

>25 BMI/body mass index (in your case the normal BMI range is 112-150lb) is considered normal so it'd be 15 pounds.

it seems that some BMI calculators show pound or two more/less but 15 pounds should be enough.
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http://www.halls.md/ideal-weight/body.ht…

Well, 125 - 135 is okay for your height :) even 140 if you're muscular!

read a bout : open the third & fourth link on : Www.lose-weight-gain.info

talk to your doctor.
drink lots of water
eat healthy

Good luck