Living in Japan has made it clear to me that cultural attitudes towards food make all the difference. It’s not like there’s a dearth of delicious things here, but obesity rates are more or less a rounding error.
Diet is a way bigger factor in weight control than activity, unless you’re a pro athlete burning thousands of calories a day from exercise because you’re working out nonstop as your job.
You should still walk for general health, but not for weight loss.
EDIT: this report from Time about Japanese food culture rings true.
Diet is the overwhelming deciding factor when it comes to weight gain.
As another commenter posted, the amount of walking even a highly active person does is fairly negligible wrt weight loss/gain. As another anecdote - my ambient walking milage is 5 miles/day and I run an additional 20-30 miles a week and still maintain an obese BMI