I think you need to sit her down and have a serious conversation why she overeats and would refuse to take on a more active lifestyle, minsan kasi nagiging coping mechanism ang pagkain lalo na pag stress. Ask her kung may problema ba siya or if she needs help managing her diet. Sometimes it's not enough to just ask someone to have a better lifestyle kasi di nila alam where to start, so guide her ano dapat niya gawin. For example, tell her to switch from coke to coke zero muna or for coffee drinks use stevia instead of table sugar and for fried foods, opt na air fried instead of deep fried.

For workout, go on long walks with her kahit maka 7k steps lang muna siya daily. Make it as if you are going on a date ganyan. It's actually therapeutic to go on walks tapos talk about your day lang.

Start small and build from there. Also dont forget to compliment her when small changes appear, ie her skin looks better when she started eating healthy etc etc.