From Longman Dictionary of Contemporary Englisheat your heart outeat your heart outa)COMPAREused to say, especially humorously, that something is very goodThat’s a great drawing. Pablo Picasso eat your heart out!b)British EnglishSAD/UNHAPPYWANT to be unhappy about something or to want someone or something very muchIf you had any sense you’d forget him, but eat your heart out if you want to. →eat
Examples from the Corpus
eat your heart out• Eric Clapton eat your heart out.• Keith Floyd eat your heart out!!• Pablo Picasso, eat your heart out.• Philip Schofield, eat your heart out.• The squaretango had to be seen to be believed - eat your hearts out, discodancers!• Kate is obviously eating her heart out for a colour changer and an intarsia carriage.• I just bought a new convertible. Eat your heart out, Jay.