I like to be careful about the use of “always” and “never.” As in “you should always do this but you should never do that.” In training, diet, and most life practices we do well when we apply “it depends.” While this talk will frustrate some self-help productivity gurus, it is a very appropriate statement with regard to liquid calories.
If you are trying to lose weight, chewing your calories is usually more effective than drinking them. Conversely, when you are trying to make gains in body mass, adding some liquid nutrition to your diet can be incredibly helpful. Shakes, usually made with fruit, protein powder, and dairy if you do it, come to mind here. Fruit and vegetable juice can also factor in here, as can milk alone. Liquid foods generally offer concentrated nutrients in rapidly digestible form, with high caloric density in most cases.
There will be times when liquid nutrition is perfect for your situation. When you need to get extra nourishment into your system easily and rapidly…shakes and the like are great. But when you are looking to control calories and increase satiety, solid foods will win out.