Diets with a lower fiber intake and caloric density appear superior for weight loss. 

Little is known about the effects of a low caloric density diets on weight loss and maintenance.  It makes sense that a diet that is lower in calories and higher in fiber will result in weight loss because lower density should result in lower calories per volume eaten.   Diets are often designed to meet prescribed macronutrient targets.  An example would be a high-protein diet which often suggests a protein intake of over 40%.   The question persists as to whether individuals can actually achieve the specified levels and if they will result in weight loss.