Calories 

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For many people wishing to lose weight,  calories will become an everyday preoccupation as reducing the intake of calories is an established, and some say the only way to lose weight.  Even those diets which don't use the counting of calories as their basis in fact often cause weight loss due to the automatic reduction of calories by means of cutting down or cutting out, high calorie foods.

For example, a low fat diet is based on the premise that not only will the calorie intake be reduced by cutting out high calorie fats but also the intake of other relatively high calorie foods such as bread and potatoes will automatically be limited because they are less palatable to eat in significant quantities without additional ingredients such as butter, spreads, sauces or items like cheese.  The same is true for other diets such as high protein or high carbohydrate diets. But what are calories and how do they work?

What are Calories?

Calorie is the name given to a unit of energy, which is defined by the amount of energy or heat it takes to raise the temperature of 1 gram  of water by 1°C or 1.8°F  so in fact, although most of us associate calories with food, they apply to all energy sources, for example petrol, electricity or gas, which is why you will often see a calorific value somewhere on your electricity or gas bills.

In food terms, the general use of the base word "calorie" is technically incorrect  as 1 food calorie is equal to 1000 calories which is the amount of energy/heat required to raise the temperature of 1 kilogram (2.2 pounds) of water by 1°C or 1.8°F.  Strictly speaking, when food calories are being referred to on packaging etc., the term kilocalorie should be used.

Although the above description may seem to confuse things where food calories (kilocalories) are concerned, most food packaging or food calorie lists showing the amount of calories will be referring to kilocalories.  The same generally applies to charts stating how many calories certain exercises burn up.  For the purpose of clarification,  in this article the term "calorie," means a food calorie i.e. kilocalorie.

How the Body Uses Calories

Everything we do requires energy,  from blinking to running a marathon, as well as regulating normal body functions such as temperature control, growth, cell replacement and breathing. We even use energy when we sleep. Through various processes, the body converts the calories in food into energy or fuel which can be used by our bodies.

The amount of calories required depends upon how much energy an individual is using.  Believe it or not, an active child can need more calories than an adult who works at a desk.

If a person takes in more calories than is required to meet their energy output, the excess calories are converted to fat which is merely a form of stored of energy which can be called upon by the body in the future should it need to e.g. in the case of famine and starvation. However, until such time the storage of excess calories causes weight gain. By the same token, the intake of  too few calories causes weight loss as the body will use any fat which has been stored for energy.

One pound (0.5 kilogram) of stored fat contains about 3,500 calories and ALL  food contains calories,  albeit some a lot less than others.

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Calorie Calculator
 

Here's a handy calculator to help you find how many calories are in  particular foods.