In recent months, Fantasia has begun documenting her intense fitness regimen (and sleek new physique!) on social media. But her transformation is much more than a cosmetic shift — it was inspired by personal loss.

“I lost my grandmother untimely from a massive heart attack, after which I began to take notice of my habits, such as what I was eating and allowing to enter my body, and monitoring stress — as well as the fact that I want to look and feel my best each and every day,” Fantasia, 32, tells PEOPLE exclusively.

For more on Fantasia and more celeb slim-downs, pick up the new issue of PEOPLE, on newsstands everywhere today.

So far, the American Idol alum — who’s up for the Best Traditional R&B Performance Grammy next month for her hit song “Sleeping with the One I Love” — has lost 20 lbs., thanks to modifications to her diet and workout routine.

“I do consistent variations of cardio, performance training and yoga,” Fantasia says, adding of her diet: “I have turned toward leaner meats, seafood, more vegetables, and cutting back or eliminating salts and sugars.”

For the past few months, Fantasia has shared her body transformation on social media, highlighting the ups and downs online.

“This Body is my Temple and I choose to take care of it so I choose LIFE,” she captioned an Instagram video of an intense workout late last year.

By: Jeff Nelson/People