MATT DAMON has become a dietician - because he's determined none of his actor friends copy his dangerous starvation diets.

Actor COLE HAUSER, one of Damon's close pals, lost so much weight for his forthcoming movie HART'S WAR he put a strain on his heart. Hauser, who will star alongside BRUCE WILLIS and COLIN FARRELL in the World War II prisoner of war movie, took director GREG HOBLIT's instruction to lose weight so he looked like he had been in a freezing camp for a year too seriously. Putting himself on the stringent zone diet, credited for helping JENNIFER ANISTON and MATTHEW PERRY lose weight, Hauser made himself ill.

Damon was distraught, having put his own heart at risk when he shed pounds for his movie COURAGE UNDER FIRE (1996) a few years ago, and again when he went on a starvation diet for THE TALENTED MR RIPLEY. Hauser says, "He warned me, 'You've got to be careful.' He really hurt himself on that movie, and he's told me many times there's a proper way to lose weight." (SVD/LADN/CPT)

Source: WENN