Even though calorie restriction works great in lab rats as the researcher can control what the rat eats and the rat can't do anything about it regardless of how hungry it becomes, it's not that simple with humans, particularly after a year or two, once the initial willpower is lost.

So, rather than fixating on lowering calories without further considerations, a more effective approach is maximizing the satiety obtained per calorie consumed. It's harder than it sounds! One might be tempted to simply consume large quantities of leafy vegetables, but that will only lead to them learning how hunger is a multidimensional experience. What do I mean by that? You can feel your stomach stretched out and full, and still feel hungry, because satiety isn't only triggered by how far your stomach has stretched, nor by the precise number of calories you have consumed.

In practice, in order to maximize satiety one must strike a balance between the volume of the food consumed, its protein content, and the amount of insulin-raising carbohydrates it contains. That's the reason so many people find success in low-carbohydrate diets, which emphasize these three satiety factors rather than the excessively simplistic calorie count approach.