The results of this study, while interesting, seem flawed to me because losing 200+lbs in only 8 months' time is ridiculously fast. I would be more interested in a study following people who lost weight very slowly and steadily over time, and curious about their metabolisms and recidivism rates.
I've lost 100lbs over the last three years and have had zero issue (so far, not saying I won't ever) with keeping at this weight. I maintained the same weight, +/- 3lbs, for most of 2015 without counting calories or following a diet. In December 2015, I decided I was ready to start intentionally losing more weight, so I tracked calories and lost an additional 15lbs over the course of three months. My experience with losing weight and maintaining weight loss are completely different than the results of the study in the OP, and I am curious how much of that difference can be chalked up to how long it took me to lose that weight.
Studies like the one in the OP are fascinating to me because no one seems to go "Hey, your body achieved homeostasis at 450lbs (maintaining that homeostasis for however many years the person was at that weight) and it probably royally screwed with everything dropping half your body weight in 8 month's time." It seems obvious to me that at that point the body is in full blown crisis mode trying to get back to the homeostasis it had developed previously. Eight months is not a long enough time to adapt to a new homeostasis, not to mention whether or not the body is freaking out because it's "starving" and dropping fat stores at such a high rate.