We've all been told to count and track calories in order to make the right food choices.

We know most people keep their eyes locked on the calorie burn indicator of their workout machines.

But how much do we really know about calories?

What are they made of? How are they counted? Why are they useful? Do we really need them?

These are some of the questions we'll answer for you so that you can make informed nutritional decisions and impart your knowledge to your friends!

1. What are calories and where do they come from?

Calories are actually really simple things!

They're basically a measure of energy of food, just like a volt is a measure of electricity, a kilogram is a measure of weight, and a kilometre is a measure of distance.

2. Why are they useful / necessary?

Basically, without calories, you wouldn't have the energy to do anything; not rollerblade, not watch TV, not even lie around surfing this website!

Every single day, your body is also working hard to do some very complicated tasks: your heart pumps blood, your lungs fill with oxygen, your body regulates its temperature, your hair grows, your stomach digests food, and many other things we're hardly aware of!

Of course, taking too many calories isn't good for you either. Consuming more calories than your body burns each day can result in weight gain, which can then lead to severe health problems.

3. How many does my body need?

Age, gender, physical activity level, body size, and physiological state can have an impact on the amount of calories your body needs to keep going!

Hence, a small child needs a great deal less than a full grown adult, and a construction worker needs more than someone working a desk job, mainly because the amount of energy each of them uses over the day is different.

In general, you'll need anywhere between:

2 200 kcal for boys 10-2 400 kcal for boys 12-2 650 kcal for boys 14-2 850kcal for boys 16 -

1 950kcal for girls 10-2 100 kcal for girls 12-2 150 kcal for girls 14-2 150kcal for girls 16-

Of course these amounts vary from person to person and day to day!

4. How are they counted?

The energy that fuels your body mainly comes from fats, carbohydrates, and proteins.

For those of you who are pretty good at maths, here's a simple way to estimate a product's calorie count:

1 gram of fat = 9 calories
1 gram of carbohydrates = 4 calories
1 gram of protein = 4 calories

Easy, right?

5. Which foods should I go for?

Some of us don't want to go into all that calculating calories stuff.

That's OK!

An alternative way of tracking your food intake and calculating your calorie balance is to have a useful calorie-tracking app on your smartphone.

Another option is to combine various nutrition-related tools available online to get to know the foods that are most likely to be safe bets for your body.

If you don't have any of these tools handy, then the best is to go with your common sense! If, for example, you're not sure of the caloric content of the chicken you're having for lunch, the cooking method (steamed, grilled, or deep fried?) can help you roughly estimate it!​