fatten out vs alter

fatten out and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
fatten out	No	No	Yes	No
alter	No	No	Yes	No

As verbs, alter is a hypernym of fatten out; that is, alter is a word with a broader meaning than fatten out:

Other hypernyms of fatten out include change, modify.

fatten out (verb)	alter (verb)
make fat or plump	remove the ovaries of
	become different in some particular way, without permanently losing one's or its former characteristics or essence
	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to