The calorie is a unit of heat, not a measurement of metabolism. It is treated as a primary, measurable quantity. This paper argues that it is neither primary nor a measurement of anything the body does. The calorie was derived from 19th-century thermodynamics and imported into biology by Atwater and colleagues. It is a derived abstraction that has been reified into an ontological entity – a ghost in the machine of metabolic research. Human metabolism does not process calories. It processes mass. The body lacks calorie receptors; it regulates behavior through mass-based signals: nutrient concentration, gastric distension, hormonal feedback. The measurement chain that converts food mass into bomb calorimetry heat, then into metabolizable calories, and finally back into predicted body mass is an epistemological dead end. It introduces avoidable assumptions and obscures the stoichiometric reality of tissue accretion and loss. The Mass Balance Model (MBM) offers a direct alternative. It tracks atoms in grams, bypassing the calorie entirely. The calorie served its purpose in the 19th century. It is time for nutrition science to abandon it and adopt a mass-based ontology. The body counts grams. It is time for the science to count them too.