Question: For some reason I feel its overkilling on the use of article(the) here, 

> 
> To refine the results, please use the categories on the left
> 
> 
> 

Can someone help?

Answer: 
In my opinion, the phrases: 

1. 'the results' - refers to the specific results that will be refined;
2. 'the categories', - refers to the specific (provided) categories; and,
3. 'the left' - refers to the specific side (i.e., not the right side, not the top, etc.).

So, I don't think the word 'the' is overused.
@shin is correct. "The" is used three times in the sentence. Each time "the" is used, the word that follows "the" gets qualified, becomes specific. The sentence is ok. There is no overuse of "the".