The Weight Loss Equation

Calories in minus calories out = your body weight.

This may seem overly simplistic but it is absolutely true and provable.

This formula is taken from the The Business Plan for the Body by Jim Karas.
The first step is to determine what your Basal Metabolic Rate(BMR) is. BMR is the amount of calories your body uses just to keep itself alive. These calories are spent breathing, pumping blood, etc.

BMR Calculation for Women

661 + (4.38 X your current weight in pounds) + (4.38 x your height in inches) - (4.7 x your age) = BMR

BMR Calculation for Men

67 + (6.24 x your current weight in pounds) + (12.7 x your height in inches) - (6.9 x your age) = BMR

Why two formulas? Well, in general, men have more muscle which causes their metabolism to be higher.

I'll use my unsuspecting boyfriend as an example:

67 + (6.24 x 178) + (12.7 x 71) - (6.9 x 38) = BMR
67 + 1110.72 + 901.7 - 262.2 = 1817.22

As Jim explains in the book, if the boyfriend did nothing but lay in bed for 24 hours, he would burn 1817 calories. (I'm going to round for simplicity sake)

Now, since he doesn't lay in bed all day (even though he may want to) we have to figure out how many additional calories he burns with his average daily activity.

This is called the activity multiplier.

Sedentary                                                                                  1.15 multiplier
Light activity (normal, everyday activities)                              1.3 multiplier
Moderately active (exercise 3 to 4 times per week)                 1.4 multiplier
Very active (exercise more than 4 times a week)                     1.6 multiplier
Extremely active (exercise 6 to 7 times per week)                    1.8 multiplier

So, this isn't black and white obviously. I can tell you that the boyfriend (I will further refer to him as FP - favorite person) has a pretty busy on his feet type job. I would love to put a pedometer on him for a day. His activity level is probably equivalent to someone who waits tables in a very busy restaurant, five days a week. The rest of the time, after work and on the weekends...I would call him sedentary. So I would probably say his activity level would be moderately active with an activity multiplier of 1.4. It's always better to underestimate than over estimate because if you over estimate your activity level, you won't get an accurate number and you won't be able to lose weight.

So now we take his Basal Metabolic Rate(BMR) and factor in his activity to get:
1817 x 1.4 = 2543.8 or round to 2544

This means he can eat 2544 calories per day as long as his activity levels don't change and not gain weight. This is also called your maintenance weight; the amount of calories needed to maintain your weight.

OK. So now what?

Well, the first thing to realize is that this is not a static number. If you have a birthday, or your activity levels change drastically (ie: an injury causes you to be sedentary or motivation gets you to the gym six times a week) or you gain or lose weight, this calculation needs to be revisited.

OK, enough with the gory mathematical details....almost.

I order to lose weight using this formula, you have to create a defecit. You have to take in less than you burn. If FP wants to lose weight he has to eat less than the 2544 calories each day that he already uses. Not just any amount will do...oh no!

One pound is equivalent to 3500 calories. So in order to lose one pound, you need to burn 3500 calories. If you divide this over a seven day week, you will have to either take in 500 calories less per day or burn 500 calories a day or a combination of the two, eat 250 less, burn 250, etc.

Having used this same formula myself I can tell you consistancy is key. You may slip on certain days, go just a few calories over, some variation is to be expected. But the more times in a row you can meet or beat your goal, the more successful you will be. And the quicker you can get back on track after a slip the better.

Next post will cover the food diary.....the ONLY way to get and stay on track.

Try the Calorie Counter at



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