When beginning writers are first learning comma rules, they have a tendency to forget that the rules all depend upon the situation. So, when you learn to place a comma before a coordinating conjunction like and, but, or so when you join two independent clauses, you might have an urge to place a comma before and, but, or so every time you use these words. You should avoid this urge!
Just because you need to use commas with coordinating conjunctions sometimes doesn’t mean you’ll use them all the time.
In this example, you don’t need a comma before the but because you aren’t combining two independent clauses. Here is a corrected version of the sentence:
You should also be careful that you aren’t using commas unnecessarily around information that is essential to the sentence. The comma rule is that non-essential information should be set off with commas, but essential information should not.
In this example, for my food is not extra information that should be set off with commas. But, you do need a comma before the so to separate the two independent clauses. Here is a corrected version of the sentence: