The move came before the release of her comeback album 'Blackout' which will be released in less than a month, reports Heat magazine.
Going by the buzz, Spears wants to slim down so that she looks her best for promotional appearances of her album.
However, doctor Halle Mir, from Los Angeles' Cedars Sinai Hospital, has warned that the lollies could cause mood swings, lower Spears' blood sugar levels and raise her blood pressure and cholesterol levels.
"If she's using it as a weight-loss tool, she's probably relying on epinephrine, which could suppress her appetite," Contactmusic quoted Mir, as saying.
"She's risking damage to her lungs and heart. She could even bring on asthmatic symptoms," the doctor said.