It's not, but the title is extremely misleading. You MUST be in a calorie deficit to lose weight. What the study shows is that simply by doing intermittent fasting, people naturally tend to eat fewer total calories per day, and can end up in a caloric deficit.
Please people, do not simply think that intermittent fasting makes you lose weight. If you still have a propensity to eat junk food or just a lot of food even in fasting windows, you could still be gaining weight or staying at maintenance.
Personal take here -- I try to time-restrict eating. I'll brush my teeth right after dinner and essentially close off eating. Git commit. Git push. Done.
The nice thing about this is how it prevents snacking at night because you're in an "off" state that is binary. I cant trick myself into thinking a tiny bit will be OK, because any tiny bit wrecks the binary state of fasting.
Good to note it's not impossible to be in a calorie deficit and not lose weight. Lipedema for instance makes it impossible to lose fat on the legs and arms. Hard to get a diagnostic for it too. Other than that your comment is right, you can also not lose weight when doing IF, it's all about calories in calories out.
Please people, do not simply think that intermittent fasting makes you lose weight. If you still have a propensity to eat junk food or just a lot of food even in fasting windows, you could still be gaining weight or staying at maintenance.