Your talking about your Mrs, who's 45, heavy smoker and maybe a bit overweight in the real world to a 20-30 year old who's been in a zombie apocalypse for several years now where food is almost non existent and you are constantly on the move everyday. I love me some fat and have no problem with it but when I'm watching a show where I'm already picking it apart for having **** that shouldn't be around years later, (bullets, gas, medicine) I tend to start picking other things apart and this is one of those issues. In my mind there is no way she would be that heavy. I am just talking about Tara here as a character on the show. I know it's stupid and something I should just forget about for the show's sake but it's just one of those things I think about watching it.
Then Maggie should've died from starvation by now then.
Don't overthink things.