The actor, who starred in Friends, now plays a washed-up version of himself in Stephen Mangan and Tamsin Greig sitcom Episodes, where the joke is constantly on him as the former star dragging a US version of their hit UK sitcom into ruin.
He told The Sun of his Episodes storylines: “The stuff we did last year about me getting overweight – that all really happened.
“I was at a hotel and I was overweight. I was lying on a chaise and I thought it was all private. This guy was in the pool and he had a gym bag and a two-year-old son with him.
“He picks his son out of the water, sits him on the edge of the pool, opens his gym bag, takes out his camera and fires across the pool at me.”
He continued: “It was on the front page of the National Enquirer the next day. The headline was Beached Male. That stung a little. There was another that said Fat LeBlanc. That was clever, I thought.”
Matt, 46, added that his former Friends co-stars Jennifer Aniston, Courtney Cox, David Schwimmer, Lisa Kudrow and Matt Perry were big fans of the BBC Two show.
He said: “The only one they were making fun of was me so everyone else came out smelling of roses – they all thought it was really funny.”
Friends is often mentioned in Episodes and asked if the others would like a cameo in the comedy, Matt said: “They probably would, we haven’t really asked them. The way the writer wrote them into it without using them was extremely efficient budget-wise.”
Episodes returns on Wednesday May 14 at 10pm on BBC2.