A calorie is a unit of energy. 1 calorie (1Cal or 1kcal) is the amount of energy required to raise one kilogram of water by one degree Celsius.
The amount of energy the body needs to sustain itself is measured in calories. As is the amount of energy food provides your body. As a general guide for weight control, in the UK it is generalised that the average man needs to consume 2500 calories daily to maintain his body weight whilst the average woman needs 2000 calories daily to maintain hers. Whilst in practical reality there are several factors that make the actual figures different for everyone, as a general guide for a starting point towards good health, the figures are very useful.
A calorie deficit is when you consume less calories than your body needs to maintain its size.
A calorie surplus is when you consume more calories than your body needs to maintain its size.
When you are in calorie deficit you are encouraging catabolic processes in your body that will reduce your size.
When you are in a calorie surplus you are encouraging anabolic processes in your body that will increase your size.
So, to simlify the above, if you eat less you will get smaller and if you eat more you will get bigger. What you eat however, along with the type and intensity of your activity levels, will have a crucial influence on the quality of your results in each scenario.
How your calorie intake is worked out.
The Basal Metabolic Rate (BMR) is used to work out how many calories you should be eating. It is calculated as follows.
- BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) + 5 (man)
- BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) - 161 (woman)
Then, more calories have to be added on top of that value depending on your activity levels.
- BMR x 1.2 for non active people (mainly sedentary)
- BMR x 1.375 for lightly active people (leisurely walking, house chores)
- BMR x 1.55 for moderately active people (30 to 60 minutes exercise 3-5 days per week at moderate intensity)
- BMR x 1.725 for very active people (45 to 60 minutes exercise 6-7 days/week at moderate to high intensity)
- BMR x 1.9 for the extremely active people (heavy manual job or over 60 minutes of high intensity exercise 6-7 days/week)
So your height, weight, gender, age, and level of activity are all used to gauge what is the ideal calorie intake for your body.
Put in the values for you to see how many calories you should be eating per day.
Now consider several important concepts that will remain the same, and effect you your whole life.
- 500 calories ABOVE your ideal intake per day = 1lb GAIN in weight per week.
- 1000 calories ABOVE your ideal intake per day = 2lb GAIN in weight per week.
- 500 calories BELOW your ideal intake per day = 1lb LOSS in weight per week.
- 1000 calories BELOW your ideal intake per day = 2lb LOSS in weight per week.
Now notice how much your ideal calorie intake changes when you change the level of activity in the pull down menu.
- The more active you are, the more you can eat without putting on weight.
- The more active you are, the more you actually need to eat just to maintain your own weight.
So if you want to lose weight, the simple fact is you need to create a calorie deficit so that you consume less calories than you burn off. High intensity exercise that burns a lot of calories enables you to eat more, and therefore obtain more essential nutrients for your body, and still be inside a healthy calorie deficit for your body.