Rapper Post Malone is sharing the secret behind his impressive weight loss.

The "Congratulations" singer confessed that he cut out one item in particular from his diet that helped him drop 55 pounds. 

"Soda is so bad. It’s so good but so bad," Post Malone shared on the "Joe Rogan Experience" podcast earlier this week. 

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side by side of Post Malone before and after weight loss

Post Malone lost 55 pounds by cutting soda from his diet. (Getty Images)

Post Malone, whose birth name is Austin Richard Post, added that he occasionally rewards himself with his guilty pleasure, an ice-cold soda, if he puts on a stellar performance. 

"[If] I had a great show, and you know what, I’m feeling a little bit naughty, I’m going to have myself a Coke on ice," he said.

The "Better Now" rapper admitted he used to weigh 240 pounds before he cut soda from his diet. Without having the sugary drink, Post Malone said his weight dropped to 185 pounds.

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Post Malone performing

Post Malone, whose birth name is Austin Richard Post, used to weigh 240 pounds. (Lorne Thomson/Redferns)

Earlier this year, Post Malone’s fans began to speculate that he was doing drugs when they noticed his dramatic body transformation.

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"I wanted to say that I’m not doing drugs, I’ve had a lot of people ask me about my weight loss and I’d suppose, performance on stage. I’m having a lot of fun performing, and have never felt healthier," Post Malone shared in part on Instagram in April. 

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"I guess dad life kicked in and I decided to kick soda, and start eating better so I can be around for a long time for this little angel," he added.

Last June, the "Circles" crooner secretly welcomed a baby girl with his fiancée. Her identity has not been revealed. 

Post Malone red carpet

"Congratulations" rapper Post Malone said he wanted to get healthy for his family. (Getty Images)

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Post Malone has candidly spoken about how ecstatic he is about fatherhood and said he planned to make better health decisions for his new family.

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"I'm excited for this next chapter in my life, I'm the happiest I've ever been," he told E! News at the time. "Time to take care of my body and my family and friends and spread as much love as we can every day."