When to use the former and the later? Example sentence:
The brunch didn't fill me (up).
In this context I would be more likely to say "fill me up" rather than "fill me". There is no rule, just idiom. "Fill me" is more likely with things like emotion, rather than food.
I had a bag of chips for lunch but it didn't fill me up.
Watching them together fills me with joy.
Other people might prefer "fill me" for food, since there is no real difference in meaning.
That being said, with food I more commonly use "full" to describe how I feel, rather than the action of being filled.
I had a salad and a sandwich for lunch, but I'm still not full.