The Sun reports that the singer made the decision after having to undergo throat surgery last year, which saw her cancel a number of tour dates. She has also taken up Pilates, at the recommendation of her good friend Alan Carr.
"Adele has found so much more energy now she's quit smoking," a source told the newspaper. "She really wants to get healthier, now that she's half-way there.
"She had always been curious about taking up Pilates but until recently there just hadn't been any time."
However, the 23-year-old has apparently told friends that she does not want to give the wrong impression to her fans. In a previous interview, she said she did not want "to be some skinny mini with my t*ts out".
Carr previously spoke out to defend Adele when she was branded "too fat" by Chanel designer Karl Lagerfeld.
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Watch Adele perform 'Rolling In The Deep' at the Grammy Awards below: