From Longman Dictionary of Contemporary Englishlet yourself golet yourself goa) to relax completely and enjoy yourself For goodness sake, Peter, why don’t you just let yourself go for once? b) to stop looking after yourself properly, for example by not caring about your appearance Poor Dad. He’s really let himself go since Mum died. → let
Examples from the Corpus
let yourself go• That left plenty of room for those wanting to let themselves go.• He's quite scholarly, but he can be really funny when he lets himself go.• If they are kind, if they care about you, they may want to know why you are letting yourself go.• One thing you could say for my daughter, she never let herself go.• People may be unusually observant and tell you that you are letting yourself go.• Perhaps Moira and Martin had almost lost each other because they were afraid to let themselves go.• Dick took me to the party and, for once, I let myself go completely.• She'd let herself go, last night - but she was none the worse for it, was she?• You can come up and let yourself go - shout about and that and muck about.• She's really let herself go since she had the baby.• I merely let myself go to impulse. 