Given a category and a set of five words, find the word from the set that does not belong (i.e. is the least relevant) with the other words in the category. Words are separated by commas.

Category: nutritional value 
Words: heavy, protein, fat, sugars, area
area

Category: bird 
Words: hummingbird, tackle, crane, hoist, tackle
tackle

Category: weather 
Words: impartial, mild, fair, luke, cold

impartial