It doesn't seem to imply that, it implies that an average Japanese man in 1960 would walk around 10,000 steps in a day and averaged 3,000 per day calorie consumption. It doesn't say that the former caused the latter. In 1960 it was still early days for automation, so many of those men would be working physical jobs in; agriculture, construction, manufacturing etc, and since vehicle ownership was far lower, would probably have walked a lot more (including carrying heavy goods). The calorie consumption will have been from a generally more physical lifestyle, not just the extra walking.