After getting slammed by her haters for packing on the pounds, Christina Aguilera has dropped a massive amount of weight -- and looking sexier than ever!

The Voice judge, who was bashed by everyone from Kelly Osbourne to the media for gaining weight in 2011, recently lost 20 pounds -- and Breaking Celebrity News has all the secrets to her slim-down success.

According to US Weekly, the 32-year-old singer finally decided she wanted to get back in shape after the haters unleashed their fury on her.

“A lot of people were on her about her weight and it depressed her,” her pal dished. “She went through a bad time because of the criticism.”

The What A Girl Wants singer enlisted in the Fresh Diet – a 1600-calorie-a-day delivery diet program which offers nutritious and delicious food options.

“She did it all on her own,” says an insider. “She goes online and picks out her food.”

An example of what she eats in an average day?