What are Calories?

Chapters Summary
What is a calorie
Calorie Example
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What are Calories?

Summary

For years I have heard about Calories. To lose weight I knew that I had to burn calories and eat fewer of them. But just what is a calorie? Thinking long and hard about it I recall a science experiment I performed in high school which involved melting ice, but honestly I couldn't answer the question. So I did some quick research and low and behold calories are really simple little things! They simply represent energy.

What is a calorie?

A calorie is a measure of energy, just as a volt is a measure of electricity, a pound is a measure of weight and a mile is a measure of distance. Technically a calorie indicates how much energy it takes to change the temperature of 1 gram of water by 1 degree Celsius. This would make more sense if the body was made of ice, but none the less this is what a calorie means.

The body needs energy (“calories”) to do anything. Just how much depends on many factors including what you do during a day (sleep all day, exercising, whatever). The average adult male needs between 2,000 and 3,000 calories a day. So if he eats this amount of energy a day he would neither gain nor lose weight. He would be consuming as much he uses. Of course the amount of calories needed per day varies from person to person and day to day.

How do calories work?

The actual amount of energy consumed per day is a simple formula:
Daily Energy needed = “Amount your body needs” + “Amount you body needs to do extra things”

The amount your body needs is the total amount of energy required for your heart to pump, your lungs to fill with air, your body to keep warm, your hair to grow, your stomach to digest food and all those things you generally don’t think about in a day. This is known as the basal metabolic rate. This is what your body would need regardless of what activities you do. Generally speaking the larger you are the higher your basal metabolic rate. Think about it: a 100 pound woman needs less energy to breath and pump her heart than a 300 pound man. This is no different than the amount of fuel a Mazda Miata needs to drive around town compared with an army tank.

The basal metabolic rate is usually pretty static, that is to say, it doesn’t change. If your body needs 1,000 calories of energy a day for your basal rate then it will need the same amount tomorrow and the day after that. It is also important to note that everybody’s basal metabolic rate is different.

The amount your body needs to do extra things is the total amount of energy your body needs to lift heavy objects, or type on your computer or walk to the store, etc. This is all the stuff that you don’t need to do just to keep alive, but you choose to do for whatever reason. Let’s consider this to be the amount of work you do in a day.

So we can now write our formula can like this:
Daily Energy needed = Basal Rate + Work

Calorie Example

Let’s say that you are sitting around watching TV all day (very low “work” energy consumed). And let's say that your basal rate is 1,800 calories/day and you only use an additional 200 calories throughout the day (walking from the TV to the bathroom, answering the door for pizza, opening a bag of chips, etc) then our formula is:

Energy Needed	=	Basal Rate	+	Work
2,000	=	1,800	+	200

So throughout the day you are going to use 2,000 calories. But let's say that you get really hungry so you order pizza. When it arrives you half of it (1,200 calories -- 300 calories per slice x 4 slices), a bag of chips (450 calories) and you down a liter of Coke (480 calories):

	1200	calories (pizza)
	450	calories (chips)
+	480	calories (Coke)

	2,130	calories

In this example spending a lazy day watching TV would consume 2,130 calories.

Now let's look at this entire day. If your body consumes 2,000 calories but you eat 2,130 calories of food:

Total Extra	=	Energy Needed	-	Energy Consumed
*-130*	=	2,000	-	2130

So you consumed 130 calories more than you needed. The problem is that these 130 calories are still in the body. And since they are not used up quickly they will be stored somewhere. That somewhere is fat. And that gives you something to do the next day...work out and lose weight!