Why are calories in food important?

November 12, 2012

Why are calories in food important?

If you are trying to form long-term good eating habits, being aware of calories is crucial.

A calorie is the measurement used to calculate the amount of energy in any food. It is important to understand the role of calories in food as eating too many will cause us to be overweight, whilst not enough will result in an individual being underweight. Ideally the number of calories we take in should be more or less equal to the number of calories we expend in our day to day life.


Depending on age and physical activity an average man requires around 2,500 calories daily; an average woman requires around 2,000.

When trying to lose weight it is essential to consume fewer calories in food and burn more calories by increased levels of physical activity. Even if you already eat a healthy and well balance diet, in order to lose weight you will still need to consume fewer calories in food.


Whenever and whatever we eat or drink we put energy in the form of calories into our body; this energy is then burnt away by our various physical activities – including sleeping, sitting, working, walking, exercise – everything we do requires energy. Being more active means using more calories; however, doing less may well lead to insufficient calories being used with the result, overtime that the excess calories are stored- as fat. Research indicates that generally speaking all of us consume more calories in food and drink than we require and, that we believe we are more active than we actually are.

In order to maintain a stable, healthy weight, the amount of calories in food we ingest should match the amount of energy we use. Of course it may well be that on some days we consume more calories in food than we expend in physical activity. However, if on another day we consumer fewer calories in food than we expend then we will still achieve an overall balance – this should be the aim of a healthy, balanced, diet and lifestyle.

Know your calorie content

When seeking to achieve, or maintain, a healthy weight it is useful to know the calorie content of the foods you eat regularly. Keeping a food diary or journal and noting our calorie intake and levels of physical activity is a great way to ensure that we maintain the correct levels of intake and output, thereby avoiding eating too much.

Most food products now have their calorie content clearly displayed on the labeling or packaging – it may be displayed under the ‘Energy’ heading and may be given in kilocalories (kcals) or kilojoules (kj). A kilocalorie is the full name for calorie – 1,000 calories may be written as 1,000 kcals. A kilojoule, however, is the metric measurement of calories. To find the energy content of a food in kilojoules the calorie content should be multiplied by 4.18.

When checking the nutritional label for calorie values it is important to take note of the indicated portion size the calories refer to – there is, as yet, no industry standard for this information and you may find that one product provides the amount of calories in 100g whilst another provides the number in a ‘portion’ – the size of which often varies.

Using the nutritional and calorie information on food packaging, or indeed in restaurants, is a useful way of keeping track of how the foods you consume meet your calorie requirements.

Weight loss

Losing weight is a simple process of taking in fewer calories than you expend – and however you do this you are bound to see results. It is possible to lose weight simply by increasing levels of exercise. The type, intensity and amount of exercise you take part in will all affect the rate at which your burn calories. By eating less and exercising more you should begin to see a gradual weight loss which you will be able to sustain and then maintain.

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