"Food wasn't good as it used to be" and "Food wasn't as good as it used to be"
Is my understanding correct? Please also correct my grammer if it's wrong.

Food wasn't good and it used to be not good.
In other words,
Food was bad and it used to bad.

Food wasn't good and but it used to good.
In other words,

Question

"Food wasn't good as it used to be" and "Food wasn't as good as it used to be" 
Is my understanding correct?  Please also correct my grammer if it's wrong.

Food wasn't good and it used to be not good.
In other words,
Food was bad and it used to bad.

Food wasn't good and but it used to good.
In other words,

Answer

"Food wasn't good as it used to be" 
"Food wasn't as good as it used to be"

These sentences are wrong.

The food ISN'T as good as it used to be.

It's a bit tricky putting this phrase into the past.
**The food wasn't as good then as it had been earlier.**

Answer

Spelling: "grammAr"

Answer

By saying "food" and not "the food", you're talking about food in general. Surely you mean some specific food ("the food")?

You're making a (negative) comparison here, so use the "as... as" pattern.

I agree with Eliot that "wasn't... used to be" is messy in the one sentence. He suggested past perfect (had been), which gives you a clearer sentence.

Answer

"The food wasn't as good as it used to be" means that  at present the food wasn't good  , but  previously it  was good.