wella wella well well...ok. heres what ya do- ask her if she wants to do this new diet you read/heard about with you. you guys could go jogging or workout together and both of you could write out menues of what is OK to eat on your new diet plan. this way you do not have to single her out by sitting her down and telling her shes fat and needs help. this would acheive anymore than making her feel like a complete loser. afterall, no one can be TOO fit and ya'll might have major bonding time in the process.