Christina Aguilera recently lost 20 pounds after being criticized by haters over the last several months for gaining weight.

"A lot of people were on her about her weight and it depressed her," said a friend of the singer, according to a Radar Online Thursday report. "She went through a bad time because of the criticism."

After The Voice judge had been slammed by celebrities and the media when she put on the pounds in 2011, the singer decided to get back into shape.  She went on the Fresh Diet, which consisted of nutritious food options on a daily 1600-calorie diet food program.

"She did it all on her own," said an insider. "She goes online and picks out her food."

One example of a daily diet included a breakfast of pumpkin-apple quinoa oatmeal, a chopped grilled steak salad with roasted tomatoes for lunch, and grilled ahi tuna with sweet potatoes and cauliflower for dinner. XTina treated herself to dessert of with apple-cinnamon cheesecake. The singer also took weight training with Tee Sorge and other yoga classes.

"She's been working hard - she wants to lose a bit more, but she feels great," said the friend. "It's more of a mind-body thing for her. She believes in exercise that she enjoys, doing strength work as opposed to intense cardio."

Tags: Christina Aguilera The Voice Xtina