On the other hand he could take it as an opportunity to slim down a little. Both Djokovic and Mardy Fish dropped some muscle and that took them to new heights for 2011 :/
I don't think Robin must become thinner, he will not be able to play the style that we all love. His game is built on power, look at Tsonga, it is much larger and he feels good and is not going to lose weight.
I think it could prolong his career as well getting a little break and recover the knees and foot to 100%. Got to find something positive in this even if it's hard
This is the single positive thing in this situation.
...of course if he is going to play ever...