Calculating calories in meals

The Biochemistry Questions Site


Answer to Biochemistry Question N-02: (e) 500 Calories



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Since usually we use large amounts of energy compared to the calorie unit used in Physics, the calorie unit used in Nutrition is different to the classical calorie definition used in Physics. While in Physics 1 calorie is defined as the quantity of energy necessary for increasing the temperature of one gram of water 1 Celsius degree at 1 atmosphere of pressure, the nutritional calorie correspond to 1000 this value (in a more accurate way, it correspond to what is called a large calorie, in contrast to the  classical “small” calorie of Physics, and should be abbreviated as Cal). It means, that 1 Nutritional calorie is equivalent to 1 kilocalorie in physics.


In the SI unit 1 physics’ calorie is equivalent to 4.184 joules, so a Nutritional calorie is equivalent to 4 184 Joules.


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