The Mathematics of Weight Loss

Yesterday Louise and I celebrated our first year of our weight loss program.  We celebrated, of course, by going out to eat.  By the way, we went to the Polo Grille in Tulsa at Utica Square and the service and food were impeccable!  Louise had a lobster tail and I had a small filet.

During the past year, I've lost 94 pounds and she has lost 60.  Together, we've lost the equivalent of a medium size person!  The term "lost" is really a misnomer; most people don't lose weight, they get rid of it!  During the last year, we've had several splurges including dinner last night.  The key is to "get back on the horse" the next day and continue your program.

I have spent a considerable amount of time during the last year thinking about weight loss and have come to the realization that it is simply a matter of mathematics.  I thought that since we both are deeply involved in this program, I would put down some of the numbers.

One of the must important numbers is know is what the experts call the basal metabolic rate, or BMR.  This is simply the amount of calories a typical person will burn in a day without doing any serious exercise (a couch potato, in other words).  The formula for BMR is as follows:

     For Men:  BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years)

     For Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)

In my case, my weight is currently 183 pounds, my height is 67 inches and my age is 70.  If you plug these numbers into the formula, it reveals that under "normal" conditions, I will burn 1581 calories per day.  If I were a woman, my BMR would indicate a total burn of 1437 calories per day.  Don't ask me how these formulas were derived, the "experts" did it.  By the way, you can find several BMR calculators on the internet.

The formulas above show several interesting facts:

     a) People who weigh more have a higher BMR.  This makes sense since larger people require more calories to move around, to keep their bodies at 98.6°, etc.

     b) Taller people also require more calories to sustain their bodies, I suppose for the same reasons listed above.

     c) As we get older, we require less calories, probably because we become more sedentary.  Notice in the formula that age related calories get subtracted, not added.

I should stop for a minute and answer the question, "What is a calorie?".  It is simply a measure of energy, just like BTU's.  In fact, one BTU equals 252 calories.  Thus, a calorie isn't some physical thing we find in food and drink but a measure of energy.

OK, now I know my BMR if I'm a couch potato - 1581 calories per day.  If I do nothing but get up in the morning, eat, watch television, and go to bed at night I'm going to need to consume 1581 calories every day to maintain my current weight.  But what to do if I want to get rid of some of my weight?

Again, the "experts" tell us that a pound of body mass has a calorie content of 3500 calories.  If you want to get rid of one pound of body weight, you need to consume 3500 fewer calories than you burn. In my case, I burn (or use) 1581 calories per day or 11,067 calories during a one week period.  If I want to lose (oops, I used the "lose" word) one pound in a week, I have to either exercise to burn calories or consume 3500 calories less than my body needs.

The math tells me that 11,067 calories minus 3500 calories equals 7567 or 1081 calories per day.  In other words, if I consume 1081 calories per day, I should get rid of one pound of body weight in a week.  I've got to tell you, 1081 calories per day is a pretty harsh diet.  What to do?  Exercise!  Exercise has two important benefits here.  First and most important is that it keeps you moving!  By now everyone knows that you need to get up off the couch and do something.

The other benefit of activity is that you get to eat more!  That's what I'm talking about!  In my case, walking for one hour per day burns an additional 350 calories of weight loss.  There are numerous charts on the internet telling you how many calories you burn doing various activities.  In Louise's and my case, we both wear Fitbit bracelets which calculate how much exercise we get and how many calories we burn.

So, the math is clear!  Weight loss (or gain) is equal to calories eaten minus calories burned (or not eaten).  The other day I did a little math to confirm this.  In the past nine months my Fitbit says that I have burned about 1,000,000 calories (yes, that's one million).  My eating diary says that, for that same period, I have eaten about 750,000 calories, or 250,000 less than I have burned.  Using our 3500 calories per pound of body mass, that says I should have lost 71.4 pounds.  My actual weight loss during that period?  67 pounds!

The math is correct - if you eat less than you use, you are going to lose weight!  So get out there and do something!