If you have any interest in dieting (and presumably you do, if you’re reading this), you’ve almost certainly come across the word “calorie”.
Maybe you have an idea what it means – in particular, you probably have the impression that too many calories aren’t good.
But what exactly is a calorie, and how do calories relate to healthy eating and your weight?
Definition of a calorie: a unit of energy
Calories measure energy, especially heat energy.
One calorie is the energy required to raise the temperature of one gram of water by one degree Celsius.
In the past, the calorie was used in fields such as engineering, but now you’ll only ever hear “calorie” use in reference to food energy – it’s considered archaic in other contexts.
The metric equivalent of the calorie is the joule, and some countries (such as Australia) have this as their food energy unit. It’s easy to convert calories to joules: there are 4.2 joules in every calorie.
What’s a kilocalorie then?
One calorie is a tiny amount of energy – so the “calories” referred to on food packaging and in diet plans are in fact “kilocalories” (also referred to as Calories – with the capital C).
1 kilocalorie = 1000 calories
With metric measurements, “kilojoules” (kJ) are always used.
From this point onwards, when you see the word “calorie”, I’m discussing kilocalories.
Calories in, Calories out
There are two ways in which you might want to track calories:
- How many you consume – how much energy you take in.
- How many calories you burn during exercise – how much energy you put out.
If you eat more calories than you need (for normal metabolic functions and for the activity which you do), then your body will store the extra energy as fat.
If you eat fewer calories than you need, your body will burn fat to provide the extra energy.
How many Calories should I be eating?
Generally, the recommended daily calorie intake is 2,000 calories per day for women and 2,500 for men.
However, the government is currently reviewing this – suspecting that our sedentary lifestyles mean that fewer calories are needed in order to maintain a healthy weight.
If you’re trying to lose weight, most nutritionists recommend a calorie range between 1,200 and 1,800 for optimum weight-loss. The more overweight you are to start with, the more calories you can eat – as heavier bodies need more energy just to function.
Try our handy calorie calculator. It lets you figure out your personal calorie needs.
You shouldn’t drop below 1,100 calories, and certainly not for an extended period of time.
A Final Word
One word of warning – try not to get too hung up on just counting calories in what you eat. There are plenty of foods that are low-calorie but of questionable nutritional value – such as many “lite” or “low” ranges.
Yes, calories matter, as they allow the energy provision of different foods to be compared – but they are by no means the only factor to consider for a successful diet.