Calorie is a unit to measure the energy Kcal is amount of energy required To raise temp of 1 kg water 1’ celsius . Nutrition Labelling & Education act 1990 National data lab:1 kcal=4.18 kg ; packaged food 1000 times larger then physics & chemistry
Old method; by burning the food in Bomb calorimeter New;Indirect method: Atwater system –using ingredients nutrition value 4Kcal for 1gm carb ,4Kcal for 1gm protein; 9 Kcal for 1gm fat; 0 kacal for water,vitamin,fibre 7 Kcal for 1ml alcohol