Calorie
Short definition
Calorie — unit of food energy; 1 kcal = 4.184 kJ.
Full definition
A kilocalorie is the energy needed to heat 1 kg of water by 1 °C, used to express food energy and expenditure; the calorie balance determines body-mass change.
Examples
A 500 kcal/day deficit ≈ 0.5 kg weekly loss.