Weight loss through walking

I’ve recently started walking a lot more ( I went from an average of 3000 steps a day to 12 000 steps) and I’m just wondering how long it takes to notice weight loss from walking. Is this a good start or will I have to do other exercises to notice changes in my body? I have also started counting calories but I find it difficult to count when I don’t know how much my food weighs. Any tips or suggestions?