Same weight, wildly different energy
Volume per calorie is the inverse of caloric density: how much physical food a given number of calories buys. A pound of broccoli supplies only around 150 kcal, while a pound of hard cheese can carry close to 1,800. The broccoli fills the stomach far more for the same energy because it is mostly water and fiber, whereas cheese is concentrated fat and protein.
Stomach stretch and the slower passage of high-fiber, high-water foods both contribute to fullness signals, so low-density foods tend to satisfy hunger at a lower calorie cost.
Eating for satiety instead of counting alone
Choosing higher-volume, lower-density foods (vegetables, fruit, broth-based soups, lean protein) can make a calorie target easier to hit without constant tracking, because fullness arrives sooner. This is a practical strategy for appetite, not a license to ignore total intake, since calorie-dense additions like oils can quietly offset the benefit.
This is general educational information, not medical or dietary advice. A qualified professional can advise on an approach suited to the individual.