The glamour model-turned-bodybuilder, 33, said that she had been watching 18-year-old Daley in the London 2012 Games and described him as "well fit".
Talking about her sporting highlights at the Games, Marsh told the Daily Star: "Tom Daley... He is fit. Well fit.
"He is very young. But I can still say I think he's fit. Plus I love the diving and the swimming. I get a bit obsessed with it. I cheered him on yesterday and was sad he and his partner didn't win a medal. But I will be watching him compete alone next week."
Tom Daley and Peter Waterfield finished fourth in yesterday's Men's Synchronised 10m Platform Final.
Daley is rumoured to be currently dating American athlete Kassidy Cook.
Picture gallery - London 2012:
Watch the stars talking to Digital Spy about London 2012 below: