diet vs fast

diet and fast both are nouns.

Word	Noun	Adjective	Verb	Adverb
diet	Yes	No	Yes	No
fast	Yes	Yes	Yes	Yes

As nouns, fast is a hypernym of diet; that is, fast is a word with a broader meaning than diet:

diet: the act of restricting your food intake (or your intake of particular foods)
fast: abstaining from food

Other hypernyms of diet include fasting.

As verbs, fast is a hypernym of diet; that is, fast is a word with a broader meaning than diet:

As verbs, fast is a hypernym of diet; that is, fast is a word with a broader meaning than diet:

diet (noun)	fast (noun)
the act of restricting your food intake (or your intake of particular foods)	abstaining from food
a prescribed selection of foods
the usual food and drink consumed by an organism (person or animal)
a legislative assembly in certain countries (e.g., Japan)

diet (adjective)	fast (adjective)
	acting or moving or capable of acting or moving quickly
	at a rapid tempo
	(used of timepieces) indicating a time ahead of or later than the correct time
	(of a photographic lens or emulsion) causing a shortening of exposure time
	unwavering in devotion to friend or vow or cause
	securely fixed in place
	hurried and brief
	unrestrained by convention or morality
	resistant to destruction or fading
	(of surfaces) conducive to rapid speeds

diet (verb)	fast (verb)
eat sparingly, for health reasons or to lose weight	abstain from eating
follow a regimen or a diet, as for health reasons	abstain from certain foods, as for religious or medical reasons

diet (adverb)	fast (adverb)
	quickly or rapidly (often used as a combining form)
	firmly or closely