Van Persie, 29, has struck 22 goals in just 30 games for the Red Devils this season reckons he is now faster and stronger that he has ever been - and he believes that bulking up is one of the reasons why he has been injury-free.
"I am on a streak of matches and goals that has never happened to me before and it is all down to my fitness," said Van Persie.
"My bodyweight used to always be around 77 kilos. Now I weigh 81 kilos. That is a difference of more than eight pounds - and it is all pure muscle.
"I haven't been spending more time in the gym lifting weights. I have got myself super-fit and as a result I am both heavier and stronger.
"It means I am stronger in battles with defenders, but I also feel like I am in the best condition of my life."