Personally I think it depends on what you mean by hide.
As far as being discreet with disordered habits, I could have scabs on my hands, run to the bathroom blatantly immediately after every meal, go to the kitchen maybe only once a day, never eat dinner with family, and drop 50 pounds in 2 months and no one would suspect anything. It's like people are blind to eating disorders when it comes to guys. You see a stick thin girl and you wonder if she has an ED. You see a stick thin guy and you think "oh it's just another boy with a shit diet and high metabolism.". Skinny girls are points of jealousy and admiration. Skinny guys are made fun of for not being muscular (though it's easier to be a skinny guy than a fat guy).
I don't think you need to hide disordered habits bc no one cares. Which I'm not personally complaining about. Of course it's an issue in the overall scale of things but it works in my favour right now so I don't care.
As far as hiding your disorder when you're in recovery or are reaching out, I think you need to hide it in certain situations and around certain types of people because it would unfortunately make people probably lose respect for you if they're ignorant to the issue. but it's important to be honest with people you care about.