Calories: the Key to Fat Burning and Weight Loss

First thing's first: what are calories?

In physics, a calorie is a unit used to express an amount of energy, such as heath, radiation, mechanic energy etc... The human body needs energy to stay alive. Basically everything the human body performs requires energy, so that means not only working out but also the beating of your heart for example consumes energy.

Nowadays a more common unit of energy is Joule [J], but in the dietry jargon, people still use the calorie as a unit. In fact, when people use the word 'calorie', they actually mean 'kilocalorie' [kcal] = 100 calories to be scientifically correct.

So, if the lable of your favourite type of biscuit says it contains 157 calories (dietry) per biscuit or 157 kcal per biscuit, it indicates that the biscuit contains 157 kilocalories = 157 000 calories (physics) = 65 732,76 Joule.

As long as you stick to literature involving dietry, fitness and health this isn't something to worry about.

The law of energy balance: basic understanding of burning fat

The intake of food provides energy for the human body. The activity of the human body expends energy. Energy that is taken in, but not used by your body, has to be stored as fat. It works the other way around as well. Energy that is needed by the human body, but not taken in by the consumption of food, has to be provided by a tissue that contains previously stored energy : fat.

This is an easy way to explain the law of energy balance, a fundamental law in dietry and nutrition.

To reduce fat, you must burn more calories than you consume each day.
To gain fat, you must consume more calories than you burn each day.

The amount of calories a specific type of food 'contains' is actually a way of indicating the amount of energy it provides. If you compare a 560 kcal Big Mac with a 114 kcal chicken soup, both about 215 grams, it's easy the see which types of food are considered to 'make you fat' and which aren't. Also the higher the frequency and duration of the activity of your body, the more calories you burn.

So, losing weight always requires a calorie deficit : a 'lack' of calories by burning more calories than you consume.

Turning quality into quantity: how do I 'count' calories?

Counting your calorie intake is easy. The label of most foods nowadays mention the amount of calories per amount of mass, volume etc...that the food contains. For not-labeled food, you can always check calorie lists on the internet or in dietry literature. It doesn't take a lot to understand that the sum of every calorie you consume per day is your daily intake. Sometimes this involves wheighing portions and some calculation but it really is worth it. Even modern technology such as computer and Iphone apps allow you to easily keep track of your daily intake.

The calories you burn a day can be determined by calculating your BMR (Basic Metabolic Rate) first. Your BMR is the amount of calories you would burn if you would sit still all day long. It's the amount of energy that is needed to complete fundamental processes in the human body such as digestion, respiration, cell-building etc... You can use the Harris-Benedict formula if you don't know your LBM (Lean Body Mass) but you can also use the Kath-McArdle formula if you do know your LBM.

Kath-McArdle formula
BMR = 370 + (21,6 x LBM in kg)

Harris-Benedict formula
Male : BMR= 66 + (13.7 x weight in kg) + (5 x height in cm) - (6.8 x age in years)
Female : BMR= 655 + (9.6 x weight in kg) + (1.8 x height in cm) - (4.7 x age in years)

Once you've calculated your BMR, you must multiplie it by your activity factor

Sedentary = BMR X 1.2 (little or no exercise, desk job)
Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)
Mod. active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)
Very active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)
Extr. Active = BMR X 1.9 (hard daily exercise/sports & physical job or
2 X day training, marathon, football camp, contest etc...) *

You now have obtained your total daily energy expenditure or TDEE.
It normally varies between 2000 kcal and 3000 kcal for men and 1400 and 2100 for women.

* activity factors source : 'Burn the Fat, Feed the Muscle' by Tom Venuto

How much should my calorie deficit be?
A calorie deficit which is too large isn't that good for losing wheight. A good guideline is to create a deficit between 15%-20% of your TDEE. Note that this is only a guideline. I recommend more detailled literature and websites for exact numbers, percentages, rules, schemes and techniques based on physiological responses from the human body on different amounts of food-intake and metabolism. The composition of your food such as the ratio carbohydrates, proteins, fats etc... also have an influence on fat burning. Since this is an article on calories I won't discuss this.

The most important part is to increase your daily amount of calorie-burning by working out. Results from dieting only works if it comes with exercising a lot. I think a good work out is one in which you burn at least 500 kcal. This requires about 30 - 60 minutes of exercise. You can find tons of information on the internet or in books on which percentage of your heart rate you should reach during a workout to get into the 'fat burn zone'. Make sure you check that out. Polar for example produces heart rate meters that allow you to calculate an estimation of the calories you've burnt so far during your exercise at any time.

Reading this article = ready to roll?

This article isn't a diet, it's just an elaboration of what calories are in order to make you understand it's value in a diet. You now have the basic knowledge to actually make it happen, so good luck!