Yes, you simply consume less calories on a keto diet because you feel less hungry. For whatever reason consuming carbs over a certain threshold is addictive.

Either way, they did not include a keto diet. Instead they used a "relatively low carb" diet of 20% carbs. Since ketosis is an entirely different metabolic state there is no reason to extrapolate from 50%-5% (keto). They have no theory so they need to actually measure this, and every single academic nutrition study I've ever seen on % carbohydrates in the diet fails to do it.