I walk and I gain

I’m 350+lbs. Started at 393 and currently 354. I’ve been losing weight through changing eating habits. I’ve now incorporated walking 3-4 days a week. I notice the scale goes UP and takes a few days to show any loss after I work out. I went from 354 on Saturday to 357 on Sunday and I know I didn’t over eat. I did take a long walk.

I keep telling myself stay the course because I know exercise is good for me mentally and physically and the scale will catch up. But man it’s a mind F.

Open to hearing any advice or similar experiences.