Table tennis palyers don't strike me as particulary fit, so I doubt that they have very strict diet. I actually wonder why they don't focus more on that part of the sport. I might be wrong but if I think about professional cyclists or a football player like Christiano Ronaldo they seem a lot fitter.
Not fit?
Have you never seen Lind, Hugo, Patrick, Dima and many more shirtless?
They are ripped and fit af.
Physique wise in the context of professional athletes they are ultimately unimpressive - definitely not "ripped and fit af". In fact even in the context of people who exercise intensely they are unimpressive. If you put table tennis players in a general physical test of Olympians - mile, pushups, pushups, squats etc. they would be in the lower quartile, I'm guessing.
However, it is of no importance. Athletes are incredibly fine tuned to the performance requirements of their sport. Consider the differences in the physiques of Usain Bolt and Eliud Kipchoge. Or think of it this way - what would be the point of judging Pyrros Dimas on his 1500 m time? If he trained even just a little bit for the 1500 he would be worse off for his events.
Same goes for table tennis players - the marginal benefit of six pack abs is probably negative. The technique requirement for table tennis massively dwarfs the physical requirement so it wouldn't make a ton of sense to spend a lot of time on GPP. Each hour spent on muscles is one not spent on your serves. Ultimately physical prowess accounts for a small portion of success in table tennis, especially since they all built the requisite fitness from when they were children.
I can't speak to the diet plans of specific table tennis athletes, but the nutrition follows the physical requirements. Add to it the fact that most TT players are young, and they can pretty much eat whatever they want and get away with it.
E: In summary physique is a side effect of performance. Not an incredibly important consideration by itself.
