1. Rob Kardashian

Although the "Keeping up with the Kardashians" star has recently posted his new slimmed up picture on Instagram. He had transformed "heavily" in those 5 years.
2. Jennifer Lawrence

The Hunger Games star seems to have transformed herself from a girl next door into a classy lady!
3. Renee Zellweger

The Academy award winner has done it all. Looked beautiful, turning into not so beautiful and then getting back to the beautiful avatar.
4. Lana Del Rey

Also known as Lizzy Grant, she is looking to have changed from beautiful blonde to a lovely brunette.
5. Zac Efron

The heartthrob of girls and High School Musical star did not have to put a lot of hard work to look completely different. He just went to gym and cut his hair.
6.Miley Cyrus

This is possibly the biggest transformation. She was once an ideal for every Disney follower and now moms hate her. But we still love her. No everyone has the courage to be themselves.
7. Justin Beiber

Child sensation has to turn someday into a gentleman and that's how he grew. He changed his style but still is a super hit.
8. Chris Pratt

Needless to say, the Jurassic world star has really worked hard on his "complete head to toe" transformation.
9. Nicole Donovan

She is aging graciously!
10. Khloe Kardashian

This incredible figured TV star has just minimized that belly to perfection.
11. Kesha

Only her beautiful rainbow hair. But she surely looks a newer version of herself.
12. Jared Leto

This American singer and songwriter chose a serious look over a dude look!
13. Bradley Cooper

This big name has transformed not only his looks but his career too to a better level.
14. Taylor Swift

This comparison says it all about what happens when a singer turns into a star singer who is always at the top of any musical chart.
15. Ariana Grande

She became a star at a very young age of 20 and hence underwent a transformation not only in her looks but in every way.
Source: http://www.wittyfeed.com/story/8141/16-Incredible-Celebrity-Transformations-In-The-Past-Five-Years