For years I've heard about how your body thinks you're in a famine situation when you go on a reduced calorie diet, so it does everything in it's power to conserve energy (calories), and that tendency is what ends up causing weight regain.

We can avoid that to a certain extent on a reduced carb diet, because even though weight loss is still a calorie game (if you eat 5,000 calories a day of fat, you probably won't lose weight), we don't necessarily reduce our calorie intake to near-starvation levels, just our carb intake to the point that we aren't spiking blood sugar and insulin to force all that excess blood sugar into fat storage.

But many of us still end up regaining weight.

So it'll be interesting to see what they find out - assuming they're still working on it, since everything has changed so much in the last couple years with the widespread use of GLP-1 drugs and the declaration that obesity is a disease that needs to be treated with drugs - potentially for life.