Daniel Andrews has been accused of hypocritical and bullying behaviour after appearing to joke about an MP's weight.

Andrew Katos, the Liberal MP who represents the electorate of South Barwon, has also accused the premier of mocking Opposition Leader Matthew Guy over his height.

MP Andrew Katos has copped criticism for his weight. Credit:Penny Stephens

A day after Labor front bencher Wade Noonan returned to work after battling a mental health issue, Mr Katos said he had struggled with weight issues his whole life, and Mr Andrews' comment had made him feel "awful".

"I know I'm a big guy, and I've had problems with my weight," Mr Katos told Fairfax Media. "I've had that all my life. It is something that has always played on my mind and at times has got me down in the dumps."