Everything You Need to Know About Calories
Calories is a big topic. I’m going to cover some of the basics that you should know if you are counting calories in any shape or form in this post.
First things first, what is a ‘calorie’?
There is some confusion between the units of calorie and the kilo-calorie. The kind of calories you’ll be familiar with if you are watching your weight are the kilo-calories. Therefore the large calorie is equal to 1,000 small calories.
A calorie is literally a unit of energy. As I say, the dietary calorie is the kilo-calorie, so that’s what we will concern ourselves with. A calorie is defined as the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius.
Burning the Calories
When you exercise, you use up energy, and so you are ‘burning’ calories.
Did you know that every movement you make, even fidgeting throughout the day, burns off calories? It all adds up. If you consciously keep it in mind to be more active throughout the day (for instance, taking the stairs instead of the elevator, or walking/cycling instead of taking a vehicle), you will burn hundreds of extra calories.
There are many ways your body can burn off calories, and many reasons why each person will burn off calories at different rates. Here are some of the things that will affect how you burn your calories:
Weight – you require more calories the more weight you have. So if you lose some weight, you won’t need so many calories.
Gender – this goes hand in hand with weight, because basically men have more muscle mass and will therefore require more calories than women.
Age – again it all ties in, for as we age, our lean muscle mass deteriorates. If you keep a very active lifestyle, then you can maintain your muscle mass better.
Drugs – Certain drugs can alter the rate at which the body uses up energy, such as antidepressants, nicotine and corticosteroids.
Diseases – Some illnesses can also alter how your body uses up its calories, such as hyperthyroidism and polycystic ovary syndrome.
How to Determine Your Calories
There are a few different methods of determining your calories:
Calorimetry – This can be direct, or indirect.
Direct calorimetry is very expensive but very accurate. It involves directly measuring the heat that emanates from the body, using an isolated chamber. So it’s not very practical for most people.
Indirect calorimetry measures the amount of oxygen you use up, because that is an indicator of the body’s use of energy. There are various ways to measure this, including using a backpack or mounted cart.
Estimates – This is the most common way, and will serve our purposes.
The most common method, used in hospitals and by dietitians is the Harris Benedict Equation. It’s a cheap and easy method for determining calories quickly.
This equation uses your BMR (basal metabolic rate), and then multiplies your ‘activity factors’ to determine your total daily energy expenditure, in calories. It’s important to note that lean body mass is not factored in – so results may be off for people who are very muscular or very fat.
You can first work out your BMR using a BMR calculator online. This involves inputting your height, weight, age and gender.
Then here is how the Harris Benedict Equation works…
You choose what kind of ‘activity lifestyle’ you believe you are, and multiply your BMR by the appropriate factor:
If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9
So as you can see, it’s a fairly simple estimation but it will give you a good overall picture of your daily energy usage, and you can use that to estimate how many calories you should intake each day, whether your goal is to gain weight or lose it.