Guessing the law doesn’t apply to tourists at the buffets in Las Vegas?
For you that haven't eaten in China. You don't order a portion like the west but you order dishes on a table. If you want some variation you will order too much if you are a few people.
How will they police this, even a communist dictatorship has its limits
That's about as much foresight as one might expect from heavy handed government action. Apparently only 50% of the population being overweight isn't enough.
