nutrition vs fast food

nutrition and fast food both are nouns.

Word	Noun	Adjective	Verb	Adverb
nutrition	Yes	No	No	No
fast food	Yes	No	No	No

As nouns, fast food is a hyponym of nutrition; that is, fast food is a word with a more specific, narrower meaning than nutrition:

nutrition: a source of materials to nourish the body
fast food: inexpensive food (hamburgers or chicken or milkshakes) prepared and served quickly

nutrition (noun)	fast food (noun)
the scientific study of food and drink (especially in humans)	inexpensive food (hamburgers or chicken or milkshakes) prepared and served quickly
a source of materials to nourish the body
(physiology) the organic process of nourishing or being nourished; the processes by which an organism assimilates food and uses it for growth and maintenance