Today I was talking with my friend's daughter. She's 5 years old. She was asking me what I do for a living (I'm sure at one time or another you have been asked this question from a child). My usual answer is that I'm currently studying and I write articles for a health site. Oddly, she was interested about the "writing" part. I told her a bit about the health topics and about weight loss, diets,etc. I was talking about "reducing calorie" when suddenly she asked me, "What is a calorie?"
I just gaped there for a second unable to come up with a simple answer. I then told her it was a measure of the amount of energy in our body like she needed a certain amount of calories for running and playing other games.
So the topic of the day is, "Do you Really Know what a Calorie is?". I'm sure all of you have heard about calories and have a vague idea as to the meaning of this term. If you are a dieter, my hope is that your knowledge of calories is higher than the average person since all nutritive values in foods are based on calories.
What is a calorie?
In basic terms a calorie is a unit of measurement of energy. Calorie was used in ancient days as measurements of "heat" or energy but it has gradually been replaced by the unit "Joule". For example, a gallon (about 4 liters) of gasoline contains about 31,000,000 calories. But we continue to use calories in relation to food.
The small calorie or gram calorie approximates the energy needed to increase the temperature of 1 gram of water by 1 °C.Calories and food
A mistake many people make is that when they see a can of soda with 200 calories, they assume the can has 200 calories in it. This is actually not the case. In America for example, when you see 'calorie' on a food package it actually means "KiloCalorie". A kilocalorie is 1000 calories.
For example, in the can of soda mentioned above, it does not contain 200 calories but 200 kilocalories (or 200,000 calories). The same applies to exercise -- when a fitness chart says you burn about 100 calories for every mile you jog, it means 100 kilocalories (100,000 calories).
In the United Kingdom, the label is "KCal" but it means the same thing. In France, the label is in "KCal" and "Kj". 1 kilocalorie is equal to 4.184 Kj.
Note: For the rest of this article, when I say "calorie," I mean "kilocalorie."
How are calories calculated?
The number of calories in a food is a measure of how much energy that food possesses.
1 g Carbohydrates: 4 calories
1 g Protein: 4 calories
1 g Fat: 9 calories
Let's say you have bought a packet of biscuits which has 320 calories, 4 grams of fat, 8 grams of protein and 64 grams of carbohydrates.
Carbohydrates: 64 * 4 = 256 calories
Protein: 8 * 4 = 32 calories
Fat: 4 * 9 = 36 calories
Total: 324 calories
If you add it up, you have 4 calories in excess of what is mentioned.
Manufacturers always round up to a whole number, so bear in mind that there is always a few surplus calories in every food item you buy and that over time, these surplus calories accumulate.
What are our caloric needs
Caloric needs vary from person to person depending on your sex, age, weight, professional activity and how much energy your body needs to work properly (also known as basal metabolic rate) and the thermic effect of food which I'll explain further down.
Basal Metabolic Rate: Your basal metabolic rate (BMR) is the amount of energy your body needs to function at rest. This accounts for about 60 to 70 percent of calories burned in a day and includes the energy required to keep the heart beating, the lungs breathing, the kidneys functioning and the body temperature stabilized. In general, men have a higher BMR than women. One of the most accurate methods of estimating your basal metabolic rate is the Harris-Benedict formula:
* Adult male: 66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years)
* Adult female: 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)
The second factor in the equation, physical activity, consumes the next highest number of calories. Physical activity includes everything from making your bed to jogging. Walking, lifting, bending, and just generally moving around burns calories, but the number of calories you burn in any given activity depends on your body weight. Click here for a great table listing the calories expended in various physical activities and for various weights.
The thermic effect of food is the final addition to the number of calories your body burns. This is the amount of energy your body uses to digest the food you eat -- it takes energy to break food down to its basic elements in order to be used by the body. To calculate the number of calories you expend in this process, multiply the total number of calories you eat in a day by 0.10, or 10 percent. If you need some help determining how many calories you eat in a day, check out these sites:
The total number of calories a body needs in a day is the sum of these three calculations. If you only want a rough estimate of your daily caloric needs, you can skip the calculations and click here
.How are calories burned in our body
It’s easiest for our body to get (extract) calories from fat (just 2-3%), less easy from carbohydrates(about 10-15%) and least easy from protein (sometimes as high as 30%!). On average you can assume that the body expends 10% of the energy in the food you eat just to extract that energy. So now you can see that calories themselves are the same, but since some foods tend to give them up so easily, they should be treated with a greater “weight” or “importance” - that’s all. Calories from fat are no different from calories from carbohydrates except that your body expends more energy getting it from carbs.Calories, diet and nutrition
Although your body treats all calories the same when trying to use them for energy, the source of these calories are important in the context of nutrition because calories from fat are more easily absorbed and stored (especially in dangerous areas like arteries, restricting blood flow and in the stomach near major organs reducing their ability to function optimally).Moral of this story:
Kids ask touch questions!Other References:Wikipedia - CalorieCalorie CalculatorCalories and KilojoulesFitness Mantra - What is a calorie?How calories work