A lot of people talk about calories: "do calories really count, why should I count my calories, is it better to measure portion sizes, than count calories," etc.
But the truth is that most people have no idea what a "calorie" means.
If you have no idea what it even means than it is very hard to understand why they are important.
So what is the definition of a "calorie"? The technical definition a food calorie (kilocalorie) is the amount of heat required to raise 1 kilogram (1 liter) of water 1 degree Centigrade.
It is a measure of heat energy.
The more calories there are in foods the more heat (energy) is released.
The word calorie is also used to describe the amount of energy stored in the body as body fat and glycogen.
A 25-minute jog burns about 210 calories and an average doughnut contains 210 calories.
If you are overweight then it means you have a lot of energy stored in your body as fat.
And if you are inactive then this energy is not released because there is no need for it.
But if you are active then this energy is needed and you burn the fat to get energy you need.
It was very important for people to store extra fat a long time ago, when food was not available.
But nowadays hunger and famine are not big problems and extra fat is not needed.
That is why fat is stored very easily and why it is so hard to get rid of it.
To lose fat you need a calorie deficit.
In other words you have to burn more calories then you consume and use your reserve energy, which is fat.
You can accomplish that in two ways.
Reduce the amount of food you eat or burn more calories with exercise.
Either way you will create a calorie deficit.
But in order to create a deficit of calories you have to know how much calories you consume.
So it is very important to count calories.
There is no way around it.
If you don't pay any attention to calories then you can easily consume more than you need.
You will have too much unwanted body fat and we don't want that to happen.
It does not matter even what foods you eat.
You can get even get fat eating healthy foods, if you consume too many calories.
And you can lose fat eating junk food if you are below your maintenance level.
It is not wise to eat junk food but you get the point.