Understanding Calories
Calories and Kilojoules
Depending on what country you live in, you will find nutrition data listed in calories, kilojoules, or both.
A calorie is a unit of measure of the energy required to raise the temperature of 1 gram of water by 1°C. A joule is a unit of electrical energy, commonly used in the physical sciences, equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second. Of course we don't use energy to raise the temperature of water or pass current through a resistance, but similar processes maintain our body temperature and perform other bodily functions.
Simply stated, calories (or kilojoules) are a measure of the energy contained in both the foods we eat and our body fat. Our bodies use the energy found in the food we eat to keep us running, and store any excess as body fat for future use.
When we expend energy it is said that we are burning calories, and when we burn more calories than we eat our bodies turn to our fat stores to find the additional energy they require. Thus when we eat more calories than we burn we gain weight, and when we burn more calories than we eat we lose weight.
Terminology in Practice
Because calories and joules are so small, when referring to food and energy expenditure it has become common practice to refer to them in multiples of 1,000. The term for 1,000 calories is kilocalories or kcal, and the term for 1,000 joules is kilojoules or kJ.
1 calorie = 4.184 joules
1 kilocalorie (kcal) = 4.184 kilojoules (kJ)
In the scientific and educational communities, it is also common practice to refer to kilocalories as Calories (with an uppercase "c"). However, outside these communities, it has become common practice to simply refer to kilocalories as calories. Therefore when you read 500 calories on a food label it actually means 500 kilocalories, and the same holds true when you calculate an activity that burns 500 calories.
Counting Calories Alone
The caloric value of any diet is the single most important factor for weight loss. The problem with counting calories alone, however, is that while it doesn't eliminate any particular foods, it also doesn't ensure that you are eating a healthy diet.
This is why our food calculator provides data on the three macronutrients: protein, fat, and carbohydrates. It also provides data on fiber to help ensure that you get enough; and on sodium to help ensure that you don't get too much.
The three macronutrients provide most of the calories found in foods. Later in the tutorial you will learn how many calories each macronutrient provides, as well as how to balance them to ensure that you are eating a healthy diet.
Heavily processed foods containing a lot of sugar and other ingredients of little nutritional value are said to contain "empty calories." Because they have little nutritional value, and little if any fiber, they don't keep your metabolism on an even keel like healthy foods do. Thus 500 calories of junk food does not have the same effect on weight loss as 500 calories of healthy food.
In truth, it isn't very likely that you could be successful dieting on cheesecake. Your mom was right when she told you to eat your vegetables; eating healthy foods is the best way to lose weight.
Balancing Calories
Calories are also used to measure the energy required to perform different activities, including the energy required just to keep our bodies running. It is therefore possible to calculate how many calories you burn in a day, which equates to the number you would eat to maintain your current weight.
If you want to lose weight, you can use the Weight Loss Calculator to calculate how many more calories you need to burn each day than you eat. This figure is called a calorie deficit.
calories eaten - calories burned = calorie deficit
Once you determine the calorie deficit you'd like to achieve, you can calculate how much less you need to eat, or how much more you need to exercise. Or you can achieve the deficit you desire with a combination of eating less and exercising more.
Understanding Calories: What They Are and What It Means
- Written by My Best Health Portal.com
- Wednesday, 26 March 2008 21:23
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Last modified on Friday, 04 December 2009 00:18
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