Learner's definition of CALORIE
a unit of heat used to indicate the amount of energy that foods will produce in the human body
foods with high/low calories
You should try to eat fewer calories [=eat less food with high calories] and exercise more.
a low-calorie diet
No dessert for me—I'm watching/counting my calories. [=being careful not to eat too much]
[more caloric; most caloric]