A calorie is a calorie

"A calorie is a calorie" is a tautology used to convey the thermodynamic concept that a "calorie" is a sufficient way to describe the energy content of food.

A calorie is a calorie

"A calorie is a calorie" is a tautology used to convey the thermodynamic concept that a "calorie" is a sufficient way to describe the energy content of food.