People see themselves in the mirror every single day. They do not need to be reminded that they may have gained or lost weight. Until they have given you room to comment on their appearance, just shut up.
We can defend Tinashe without acting like Chris Brown isn't an amazing artist. Saying you can't name 5 Chris Brown songs wouldn't even be enough to convince yourself. And the Tinashe song he's on, is a big bop too. He has a lot of shortcomings - music is NOT one of them.