empty calories
Calories from food that lacks actual nutritional value (often junk food). No wonder you're hungry again—you only ate empty calories earlier.
empty calories
Food that has little or no nutritional value. For example, Snacking on beer and potato chips makes for a lot of empty calories. [1960s]
empty calories
Food that has little or no nutritional value but adds to one’s caloric intake. This expression was born in the diet-conscious era of the late twentieth century and applied to, for example, liquor, soft drinks, snack foods, and desserts, as in, “She loads up on empty calories like potato chips.” It is on its way to clichédom.