I tend to hang out with hundreds-to-thousands of endurance athletes [0], and the large plurality of them are not heavy people. Sure, there are some that don't run competitively and take around an hour to do a 5k with their friends. They do tend to be a bit curvier and say things like "I run for donuts" or "I've gotta work off my beer somehow". By and large, though, people who are consistently running throughout the week are not overweight. Some of us also eat a ton to support this.
All this is to say that I suspect our cultural understanding of "normal movement" is near zero minutes per week, and "exercising" is only slightly above that. The study itself references 150 minutes per week of moderate exercise out of the 6,720 waking minutes available. Allotting just over 1% of time to exercise does not strike me as the type of strategy that would effect meaningful change. In fact, 30 minutes is a relatively easy 5k time— a distance which most coaches would say a healthy adult can shake off and be well rested from within 24 hours. 25km per week is a very low volume for someone expecting to see a physical change.
Unfortunately, the levels of activity that do have a positive impact on peoples' lives are often described as "insane amounts" or other discouraging descriptions. Indeed, it takes time to adjust from old normal, where 292.6 minutes per day of television does not seem out of place, to a new normal where investing in ones body (and mind!) is given a high priority.
I haven't finished reading the second referenced study, but I'm seeing the same thing— small impacts at the start of something. The first random referenced study [1] I picked had this to say:
> The results suggest that dieting is associated with weight loss followed by regain after treatment ends, whereas exercise alone produced smaller weight losses but better maintenance.
The key, from my experience, is adopting a lower-weight lifestyle. We've all seen friends attempt a new diet and it never works, as TFA explains. Unfortunately we've built a culture of obesity, and cultural influences are very difficult things to avoid.
[0] https://ultrasignup.com (These are all over the country, and not all of them are ultramarathons)
[1] https://www.sciencedirect.com/science/article/abs/pii/S00028...