Better than just youth

Christian hurried to home as the world went crazy. Suddenly, everybody became no older than 20 years old. He didn't know yet but it was the first Youth Day. But as nobody knew back then what happened and how long it will last, everybody was panicking and/or enjoying this miracle.
In this moment, Christian wanted to see Karen, her 55 YO beloved wife.

"Karen ? Where are you ? He screamed when he finally arrived.
- Upstairs !"

Christian ran into their room, in the first floor. Inside, he discovered a young lady almost naked.

She looked like her wife but...

"You're... you're young... and beautiful ! But... you weren't that thin back then ?!
- I know right ? she smiled with bliss. At first, I just rejuvenated to be the overweight girl I was back then. You can guess I was disappointed as everything I took so much time to lost was back again. But it suddenly disappeared. The miracle made me not only younger... but also thinner than I was !"

So happy to see herself more beautiful than she ever was, she took off the last piece of clothes she had (her pants) and together, on their bed they did like almost 80% of adults on Earth...

** Here comes a new rule for Youth Days. I asked myself what could happen if someone was fat/skinny in his/her youth or ill or handicaped. My answer : the phenomenon doesn't just rejuvenate someone. It makes his/her body into the healthiest condition**