My wife has let herself go...

We have been married for 4 years and our kid is now turning 3. My wife is about 25 Kg heavier than when we first married and she also doesn’t bother with her hair, make up or clothes anymore. I miss the way she looks and I don’t feel sexually attracted to her anymore. She’s a good mum and wife and I still love her. I have not cheated on her and don’t intend to, but I would like her to start grooming herself again. How do I talk to her without upsetting her? Thanks! #wives