What Is a Calorie?
Quite simply, a calorie is a unit of energy. Within nutrition calories refer to the energy that is consumed through eating and drinking, and how it is used up through physical activity. While an apple contains 80 calories, a 1 mile walk will use up approximately 100 calories.
There are two types of calories, small calories and large calories. One large calorie (1kcal) = 1,000 small calories. Calories used in food labels are, in fact, kilocalories. Kilocalories are units of 1,000 small calories. Therefore, a 250-calorie chocolate bar actually contains 250,000 calories. In English, the term calorie has come to have the same meaning as kilocalorie, and the two terms are virtually synonymous, therefore in most cases, a calorie and kilocalorie have the same meaning.
Internationally, people discuss food energy in kJ (kilojoules). 1 kcal (kilocalorie) = 4.184 kJ.
What Are Calories Used For?
Of the energy we take in through food and drink, 20% of it is used for brain metabolism. Most of the rest is used for the basic metabolic requirements – such as the circulation of the blood and breathing. If we exist in a cold environment our metabolism will produce more heat to maintain a constant body temperature. When we are in a warm environment, we require less energy and therefore use fewer calories. Calories are also used to provide the mechanical energy for our skeletons and muscles that allow us to move around, and for the purposes of respiration – helping us to breathe.
How Many Calories Should We Be Eating?
As humans we need energy to survive. Without it our hearts and lungs would stop, and we would die. The energy that we require is found in food and drink. There are several factors that dictate exactly how many calories we should each be eating, including how old we are, our size, height, sex and the lifestyle we have, along with our overall general health. A tall and athletic young man will require more calories than a short and more sedentary retired woman, for example.
Daily calorie intake recommendations vary across the world. In the UK, the NHS recommend that the average male adult needs approximately 2,500 calories per day to keep his weight constant, while the average adult female needs 2,000, however in the US the authorities recommend 2,700 calories per day for men and 2,200 for women. It is important to note that rates of obesity among both adults and children in the USA are considerably higher than in the UK and other parts of Europe.
These days, doctors are more likely to stress that rather than counting calories we should all focus much more on consuming a healthy and well-balanced diet, and be more physically active, so that we burn off the calories that we consume every day.
What Happens When We Eat Too Many Calories?
Recent figures have suggested that in England 65% of men and 58% of women are overweight or obese which can only mean that many of us are eating too many calories. Over time, eating - or drinking - high calories food and drinks, means we are consuming more calories than we need and we will put on weight. Our bodies store any excess calories as body fat. Of course, the more weight we are carrying around the greater our risk of other health-related problems, such as type 2 diabetes, heart disease, stroke and some cancers.
Increasingly over the past few decades, more and more sugar has been added to foods sold in supermarkets while food labels are not transparent enough about the contents or added sugar contained within. In the West we have increasingly become fond of eating large portion sizes and this is a particular issue in restaurants and fast food outlets. For example, in the USA the average cheeseburger in the 1990s contained 333 calories. That figure has now risen to over 600 calories.
High Calorie Foods and Drinks to Avoid
Besides reading food labels and trying to ascertain calories contents keep an eye out for the following high calorie foods:
How to Reduce Your Calorie Intake
If you think you weigh too much you are probably eating 500kcal more than you probably should be every day. Ask yourself where do those extra calories come from? What can you cut from your diet so that you can reduce the number of calories you consume on a daily basis?
Make sure you are active. You should be engaging in physical activity that amounts to walking three or more miles per day as well as any normal physical activity you typically do every day such as vacuuming and climbing stairs.
Eat larger meals at the start of the day. Opt for a larger breakfast and a smaller supper.
Swap high-fat or high-sugar foods for healthier alternatives that contain fewer calories. Eat smaller portions or cut the size of the plate that you use to trick yourself. We do tend to eat what is served to us even if we are full up.
Avoid supersizing or choosing large portions of food or drink when you are eating out.
Know the calorie content of different foods and drinks so that you are aware that certain items are not to be consumed in large amounts.
Will I Lose Weight If I Reduce the Amount of Calories I Eat?
You will lose weight if you reduce the amount of calories that you eat, but it will take a long time so you must bear with the process. Aim to lose about 0.5-1kg (1lb-2Ib) a week until you reach a healthy weight for your height. This can take many months - even years, but it's not a race. You can lose this weight simply by eating and drinking approximately 500kcal to 600kcal fewer a day than usual.
Remember however, that a healthy diet is not simply about eating the right amount of calories. You need to eat a wide range of foods, to ensure you get all the nutrients you need.
Finally! Stay active – the more you move about the more calories you will burn up and you'll be looking sleeker and feeling fitter much sooner.