The Pontiff also had a tailor made joke for First Lady Melania
Pope Francis has teased US President Donald Trump about getting fat.
During his visit to the Vatican, the Pontiff suggested that he was putting on weight.
News agency AFP says he asked First Lady Melania Trump: "What do you feed him on? Potica?"
This was a reference to a calorie-laden cake that comes from her native Slovenia.
Reports say President Trump took the quip in good part during the 30 minute meeting.
Mr Trump is a fan of fast food, such as KFC, having been pictured eating them during the presidential campaign last year.
He was also pictured tucking into a taco bowl to mark the Cinco de Mayo holiday earlier this month.
On August 2nd last year, Mr Trump tweeted the photo of him with a KFC meal while travelling in between states.
Great afternoon in Ohio & a great evening in Pennsylvania - departing now. See you tomorrow Virginia! pic.twitter.com/jQTQYBFpdb— Donald J. Trump (@realDonaldTrump) August 2, 2016
And in May, the then-president elect Instagramed a picture of himself as he digging into a McDonald's meal on his private jet.
During the event, Pope Francis gave US President Trump a medal featuring an olive branch.
The Pontiff and Mr Trump have had public disagreements in the past.
Mr Trump said it was a great honour to meet him, tweeting: "Honor of a lifetime to meet His Holiness Pope Francis. I leave the Vatican more determined than ever to pursue PEACE in our world."
Honor of a lifetime to meet His Holiness Pope Francis. I leave the Vatican more determined than ever to pursue PEACE in our world. pic.twitter.com/JzJDy7pllI— Donald J. Trump (@realDonaldTrump) May 24, 2017
Additional reporting: Michelle Mac Mullan