Oversleeping is no more healthy than overeating.
This camera is no more big than my hands.
In native English, these two sentences are incredibly uncomfortable, in a word they are wrong.
(The fact that they may or may not be grammatically correct is a naive path of enquiry. This sentence not not the other not not sentence is 'grammatically correct', and that fact is of no value.)
The remarkably obvious, common way to state the first type of thought is:
Oversleeping is just as bad as overeating.
"... is just as bad as ..." is a very common formulation in English rhetorical exchanges, and, in this setting (which is an exact example of it), anything else sounds weird.
For the second one,
This camera is no bigger than my hands.
Ditto on that formulation. The incorrect sentence is so close to a common phrase, yes so incorrect, that it sounds very incorrect. Indeed, it's a perfect example of "humorous foreign English" where one fluffs a common phrase.
Further, note that a similar-sounding common formulation in a certain type of argument is ".. no worse than .." where you are "throwing back in the other person's face" some relevant negative point.
You tell me "You shouldn't smoke so muchy, smoking is bad"; my response "It's no worse than alcohol!" (In the example, the first party drinks a lot.)
The first given incorrect sentence is particularly bad because it sounds like one is trying to use that formulation, but has everfthing messed up on a couple of levels. To wit, it sounds like the speaker has confused a use case of the "just as bad as" formulation with a use case of the "well that's no worse than" formulation. (And, additionally, messed-up the words anyway.)