Aaron Carter is proud of the progress he's made in rehab.
The pop star, who checked back into a treatment center for a second time last month, shared a before and after photo of his 45-lb. weight gain to Instagram on Friday.
"I went from 115 to 160 pounds in two months," Carter wrote. "I feel amazing. 2018 I'm ready for you!!"
A source tells E! News Carter is still currently in rehab and on a "special" protein-heavy diet, which has enabled him to put on the weight so quickly. In early October, Carter shared a similar side-by-side image showcasing his 30-lb. weight gain.
Carter, 29, initially entered rehab in September "to improve his health and work on his overall wellness," according to his rep. He later left the facility as "several legal and personal matters arose that required his immediate in person attention," only to return a week later.