The Practice

That’s the theory over and done with now you need to work out what your TEE is for an average day. There is little point in trying to manipulate the TEF calorie value to lose weight – it is poorly understood and generally accounts for 10% or less of your calorie usage. I will simply assume, therefore, that it makes up 10% of the calories you eat. Even if TEF was well understood so that one could choose high TEF foods, without restricting the amount eaten weight loss would be so slow as to be non-existent.

Since TEF is essentially fixed as a proportion of what you eat we therefore need to find out what the BMR and PA calorie measures are. PA is generally fairly easy to estimate. If you aren’t doing any exercise then your PA is essentially zero. While strictly speaking BMR doesn’t include any exercise walking for thirty seconds from your car to the office doesn’t consume enough calories to be worth counting in your PA. To be worth counting exercise needs to get your heart rate up above your resting rate for at least five minutes at a time. It doesn’t matter if you do all your exercise in one go or in stages throughout the day just try and make it at least five minutes at a time.

I find walking a very good way to burn a few calories. Step counters have become very common and cheap (you can often find them at pound shops) so measuring how far you walk is quite easy. Assuming that you are near average height and not massively overweight you will burn about one hundred calories per mile walking at four miles per hour. Measuring a mile can be tricky without a map but as a rule of thumb a mile requires 2000 steps. I also found that Google Earth is a good way of finding out how far you have walked as you can plot a course that it measures for you. Walking three miles a day therefore burns around 300 calories and will take about forty five minutes – this is a good amount to aim for if you haven’t been doing exercise before and it will stop you from feeling lethargic.

The bulk of the calories you require in a day are to cover your BMR. BMR is well understood and you can calculate your bodies BMR with a good degree of accuracy. There are four variables used when calculating your BMR: your gender, your weight in kilograms, your height in centimetres and your age in years.

For Men: BMR = 66.4730 + (13.7516*w) + (5.0033*h) – (6.7550*a)

For Women: BMR = 655.0955 + (9.5634*w) + (1.8496*h) – (4.6756*a)

Where: w is weight in kg, h is height in cm and a is age in years.

For example: I am male, 90kg, 180cm and 31 years old so my BMR is 1995 calories at the moment. If my average daily intake of food is 2500 calories, which it is roughly, and I am burning 300 calories a day in exercise we can work out what my TEE is:

TEE = 1995 + ( 2500 / 10 ) + 300 = 2545 Calories

Since 2545 is greater than 2500 we can see that if I was to eat 2500 calories a day I should very slowly lose weight. The error in these numbers is large enough that in reality it’s hard to tell whether I would lose weight or gain weight over the long term. In all probability I would maintain the weight I am at now which from experience is exactly what has happened.

In order to loose weight you need to eat less than the TEE of our body. How much below your TEE you consume determines how fast you lose weight. Believe it or not you can actually calculate how quickly you will lose weight based on you calorie intake.

Every kilogram of body fat that you are carrying around contains approximately 7000 calories. If you eat 1000 calories less than your TEE every day for a week you will lose one kilogram. In imperial measurements a pound of fat is approximately 3500 calories so you would lose roughly two pounds a week. Work out the difference between what you weigh now and what you would like to weigh, this gives you the amount of fat you want to lose. In my case I’m aiming to lose 10kg of fat which equates to 70000 calories. At 1000 calories a day below my TEE it would take me seventy days, or about two and a half months, to lose my excess weight. If I ate only 500 calories below my TEE it would take 140 days or about five months.

The above calculation is fairly rough and ready but it gives you a guide for how long it will take you to lose your excess weight. The reason it can only act as a guide is because there are many other variables that affect the rate you lose weight that aren’t include in the calculation.

For example, if you simply sit around when you try and lose weight your body with reduce its BMR, potentially by removing muscle mass, and therefore your TEE will drop. If you haven’t exercised before you started dieting you will find that you will put on muscle quite quickly. Muscle weighs substantially more than fat so although your body fat will reduce your weight may not drop as quickly as expected. A small number of people will also find that they begin to retain some extra water when they try and lose weight – water weighs a kilogram per litre – this should correct itself over time.

In order to be able to slim down to your desired weight you need to know your TEE at you desired weight. In my case I want to weight 80kg so plugging the numbers into the BMR calculation again I get a BMR of 1858. Assuming that I continue to do 300 calories in exercise and aim to eat 2000 calories my TEE is:

TEE = 1858 + ( 2000 / 10 ) + 300 = 2358 Calories

Since 2000 is much lower than 2358 this indicates that I would continue to lose weight which is not my goal so I need would need to up my calorie intake. Taking another guess at eating 2350 calories a day gives:

TEE = 1858 + ( 2350 / 10 ) + 300 = 2393

As 2393 is approximately the same as 2350 I should, give or take, maintain 80kg. Note that this figure is approximately the same as the 2500 calories a day recommended for an adult male. I am slightly shorter than average which accounts for my slightly lower TEE value.