There is a huge cultural gap between pakistanis raised abroad and those raised in Pakistan.
Pakistanis abroad have been raised with manners... We know its not appropriate to insult anyone because we are sensitive of their feelings.
When I visit Pakistan, I am constantly shocked at how rude and crude Pakistanis are. They insult you to your face, calling you fat, ugly and constantly compare themselves to you. Its inherent in their nature and most importantly they think its OK.
I honestly think she'll eventually change once she comes to live with you in the UK, but you have to give it time. Once she moves to the UK explain to her the cultural norms and what is and is not acceptable to do and say..
I agree with this statement. They have to comment on the way someone looks like. The comparison will always be there.