Question

scientific reason of to measure the energy we get from the food the unit used is kilo calorie

Answer 1

Actually we don’t, we use kilocalories, or “big” calories. We just call them calories for convenience. This sloppy use of terms is widely used when talking about human nutrition but in any other context you would assume the precise definition.

A calorie is the amount of energy required to raise the temperature of one gram of water by one degree celsius. Our nutritional calories can thus raise 1kg of water by 1°C.

There are other units for energy that could have been used (ergs, joules, kWh, etc.) but I believe the use of the calorie reflects the unit that was widely used by biologists, chemists and nutritional researchers, the people that established the caloric content of food. It just makes more sense to use a unit tied to water and heat, as opposed to a unit tied to electricity or mechanical motion. If you work with electricity all day, you’re going to use kWh. If you work with mechanical energy, you’ll use force-times-distance units for energy. If you work with food, you use the calorie.

Answer 2

In order to answer this question, it helps to define a calorie. A calorieis a unit that is used to measure energy. The Calorie you see on afood package is actually akilocalorie, or 1,000 calories. ACalorie (kcal) is the amount ofenergy needed to raise the temperature of 1 kilogram of water 1 degree Celsius.