Eighteen months into their marriage, the Grammy winner revealed that wife Luisana Lopilato is his fitness guide. "It's much easier when you're with somebody who's that disciplined," he said of the model’s dedicated workout routine in a 2012 interview with Daily Mail.

"I've gone on diets, and I've gone up and down with my weight. But keeping healthy is certainly simpler when you're with your wife and you say, 'What do you want to do today?' and she says, 'Let's go to the gym...'" he explained.

Michael added that his eating habits had also improved. "In some of those [old] pictures of me I looked pregnant!" he confessed, noting that he "cut out bread, rice, and pasta" to achieve his slimmer look.

A few months after welcoming his and Luisana’s second child in 2016, Michael again showed off a smaller figure as he left the hospital following vocal surgery. But in November of that year, the "Haven’t Met You Yet" songwriter retreated from the public eye after announcing that his then 3-year-old son, Noah, had been diagnosed with liver cancer.

In a "Carpool Karaoke" segment with James Corden two years later, Michael discussed his fluctuating weight in an effort to lighten the mood following questions about his son’s health battle.

"There’s a fat Bublé, a chinny Bublé, and then there’s a 'Hey, I’ve got a record coming out maybe I should stop eating those Slurpees,'" he teased, adding that the appearance of a certain body part motivates him to keep the pounds off. 

"I feel like when you’re smaller your penis looks bigger," he shared. "Because when you’re bigger like that it looks like a buoy sitting in the middle of an ocean."