Anecdotal, but this mirrors my experience as well; without fail I lose weight on every trip. I’m not necessarily doing that much touristy stuff either but I walk significantly more than I do back home (I also work from home which probably doesn’t help). Part of it might be that I have more time as I’m in Japan for a holiday but I also find most of Japan more interesting to walk around and the cities are more densely packed with fewer stretches of empty land. I also don’t have a car which probably forces more walking but I often actively chose not to catch a train as well, even if it makes the trip a little longer.