Part of the issue for people trying to lose weight is that their metabolism slows down to avoid burning calories. The body doesn't like giving up calories that it has already stored, and when it has to do so, it basically figures that times are tough, and it doesn't know when they're going to be good again... so it reduces the metabolic rate, and increases storage of excess calories when they do come in. It's thought that this effect may be permanent, but even if it's not, it is certainly a long lasting one, and it's one of the reasons that, even years after losing a large amount of weight, people have a hard time keeping it off (and most fail). Being able to re-tune ones metabolic rate would help overweight and obese people immensely in not only taking that weight off, but keeping it off in the long run.
(Of course, this all ties back into the microbiome in the gut as well. The real takeaway from all the new research into obesity is hardly surprising: The human body is complex, and is extraordinarily good at storing and using energy in efficient ways. Modern diets are only about 10,000 years old, and the calorie rich eating of today is less than 100 years old. And our bodies are still evolved to run during boom and bust cycles, where even the boom cycles are pretty thin compared to the energy uptake/use ratios that the average person has daily.)