I hate the join the "unreliable anecdata faction" in a thread where we are talking about well-established science-backed points (eating 1000+ extra kcal of trash most days contributes to being overweight; walking 10x more every day does the reverse), but I too believe there is something
magical (meaning we don't fully understand the science) about walking.
I have three kids, and after each one of them, I tend to put on 10-15kg of body mass, mostly the wrong kind. So I have three experiences of "fixing it".
The first two times, I ran, lifted weights, ate salads and dropped alcohol, all that shit... it worked, but it was hard. Hard like when I quit smoking cigarettes (before the first kid). I was hungry. Irritable. Sometimes, I'd be like "oh, fuck it!" at 1AM and make a big ass instant Japanese ramen with scrambled eggs on the side, I was so hungry.
The third time, I eventually bought one of those under-desk treadmills, because despite my vows to walk 10km per day I just "don't have time".
It took about a day to acclimate. After that, and forever more, I can easily do computer work (writing code, reading code, architecture diagrams, writing docs) while walking 3kph (slow). When I am just reading stuff, I ramp it up to 4-5kph.
There are a bunch of other things that made me feel dumb for not doing it years earlier, which one day I might blog about or something. I suspect it actually helps my productivity — including learning rate and retention — for some reason (bleeding off extra energy that my mind might otherwise use to poke me with small, fascinating distractions?). But sticking to this topic, the main point is this: I was no longer super hungry with only 2000 kcal a day.
When I would run 750kcal off, sure I burned the calories, but I was soo hungry later that I would override my caloric restriction plan, and often end up eating more extra than I'd burned off.
Not at all the case with walking, either on the desk treadmill, or in the relatively uncommon case that I get to walk 10km in the real world (maybe once a week I will walk to/from work and take some detours).
My weight dropped steadily — which, of course, it does any time I manage to consistentely burn ~500kcal per day more than I consume — but the point is it dropped easily. Walking 10km/day, I can eat at a deficit without it being so... annoying. Eating to maintain weight is also easy.
And unlike lifting weights, or HIIT, or running hard — you can literally walk 10km every single day. You can take a day off if you want, but you don't need to[1]. Your muscles don't need rest. Your joints don't wear out. It's literally the activity your body was designed for. You can do it every single day for 10 years if you want.
I should really write that blog post.
I suspect some science-type should dig into it more and write a whole book.
[1]: the only real worry is that if you have already gotten super out of shape (very fat, very low cardio fitness, etc) then you should start with less walking per day, and work your way up gradually.