The word calorie is now a very commonly used and understood word in nutritional health, worldwide. What with obesity taking on epidemic proportions and an established strong link between calories and weight status, people are now well-educated about the consumption of calories.

High consumption of calories causes weight gain. Knowing the calorie content of various foods, therefore, becomes important for those people who are conscious of their weight. This helps them to choose foods that contain the right amount of calories and keep their weight at the optimum.

Calorie Definition

A calorie is defined as a unit of heat energy. In nutrition, a calorie is basically used to quantify the energy released from the foods and drinks that we consume and digest.

When a particular food item contains 100 calories, it means that is the amount of energy you can get from eating or drinking that food item.

This energy, provided by the foods to the body helps the body to carry on its various functions.

We always regard calories in a negative fashion associating them with being overweight and obese. However, though extra calorie consumption does lead to weight gain, it is necessary for you to know that they are an essential part of living. Consume just the right amount of them and you will be okay.

Calories classified into two types

The definition of a calorie is classified as follows:

  1. The small calorie or the gram calorie (cal). The small calorie quantifies the amount of heat energy required to raise the temperature of one gram of water by one degree centigrade at one atmospheric pressure.
  2. The large calorie or the kilogram calorie (Cal with a capital ‘C’ or kcal). One Cal or kcal equals 1000 cals and is the amount of energy required to raise the temperature of one kilogram of water by one-degree centigrade. This is the nutrition calorie or the dietary calorie or the food calorie and it is this calorie that is usually referred to in the nutritional context.

However, in the nutritional context, usually the word ‘calorie’ is used though it actually refers to a kilocalorie. The word “Calorie” you see on food package labels is actually a kilocalorie, which in effect is 1,000 calories. It is referred to as Cal or (with a capital C) kcal

Technically as explained above, their definitions are different. Similarly, during exercise, the amount of calories burned refers to kilocalories burned.

Here, a small reference to joules is required. Joule is the common unit of energy used in physical sciences. One calorie is equal to 4.184 joules.

Although the Calorie (kilocalorie) is still in use, in nutrition, the kilojoule (kJ) is the SI unit of food energy. SI refers to the International System of Units, which is the modern form of the metric system.

What calories do? Why are they important?

Calories are required for the energy that our body needs. Just as a car needs gasoline to run, so does our body require them as fuel.

The foods that we eat are digested and metabolized in the body’s cells. Calories are the amount of energy produced when the food you eat is broken down by the body. Every cell of all systems of the body requires them to carry out its cellular function.

They are used by the body through the metabolism process by which enzymes are released. Calories metabolize:

Calories are burnt to produce energy for physical activity and internal body functions such as breathing, pumping blood, etc and any excess is stored in the body as fat, irrespective of which nutrient they come from. That is why consuming excess calories leads to a build-up of fat in the body, which causes weight gain.

Sources of Calories

Calories are obtained from all the foods that we eat every day such as proteins, carbohydrates, and fats. They are found in all foods, some contain more than others.

But, one thing goes undisputed and that is: – they are an essential part of living. The number of calories obtained from one gram of the nutrients is shown below:

  • One gram of carbohydrate gives you 4 calories.
  • One gram of protein gives you 4 calories.
  • One gram of fats gives you 9 calories. Fats are the most energy-dense nutrient. There are 3500 calories for each pound of body fat.
  • Water, vitamins, and minerals are all calorie-free.

Your Calorie Requirement

Calorie requirements vary from individual to individual and the factors that influence this requirement are age, height, weight, the person’s physical activity level, and some other factors. An adult requires more calories than a child and similarly, a person who does physical work such as a laborer requires more of them than a person who has a desk job.

However, for a normal-statured person, the calorie requirement to maintain weight is given below. Bigger stature people and those who are physically more active require more while small and sedentary people require fewer calories.

  • Men require 2500 cals
  • Women require 2000 cals
  • Children below 5 to 10 years need 1800 cals.

What are Empty Calories?

Empty calories are those, which do not offer any nutritional value to your body. They are found in foods, which contain a lot of solid fats and added sugars and very little or no nutrition. Examples are junk foods. Junk foods are foods that offer little or no nutrients, vitamins, and minerals, and are high in kilojoules (energy), salts, sugars, and fats.

This nutritional deficiency causes your body to hunger for these nutrients and you end up eating more of these empty calories. Eating foods with empty calories, therefore,  tends to cause weight gain and lack of nutrition makes you weak.

Junk foods that contain a lot of empty calories

These are typically bakery items, candies, and processed foods.

  • Cakes, pastries, donuts, cookies
  • Candy, lollipops, and licorice
  • Cheese
  • Pizza
  • Energy drinks, sports drinks, fruit drinks, sodas
  • Bacon, sausages, hot dogs, and other deep-fried foods
  • Margarine, butter, and cream