Anyone here has experienced loosing weight like 20 pounds or more?!

I went from 137 to 115 in 3 months
I cut out snacks, no muffin/bagel for breakfast- nutrigrain bar instead, salads for lunch, smaller portions
I did jumping jacks everyday, and 200 crunches
It wasn't hard, but now people think I'm too thin. Haha. And nope no stretch marks or anything, but then again I'm only 18 (:

mainly start w/ your diet. eat when hungry,but better choices like banana,yogurt,popcorn, chips n salsa(fresh homemade) easy to make, Choose carefully a good 4 u cereal too. I like special k oatmeal squares or fiber bran variety. Its best if there is not always fatty junk food readily available. Once you get on diet u will see how u feel good when u eat good. It all falls in place . when u feel good u will more likely start a exercise routine. (start simple) it wont take much just keep it routine! you will notice within 3-5 days muscle begin 2 tone. It will be motivation just feeling and seeing . research some simple muscle toning butt, arms areas you may want

cut back at least 1000 calories a week, eat small portins every three hours like fruits n granola bars
i ran every other two days a mile and a half....and lifted weights daily...small portions.

went from 226 to 195 in 2 1/2 months

I used the website calorieking.com. it tells you how many calories to eat, without even exercising, to lose 1 - 2 lbs a week.

started at 160 now at 125