The Mathematics of Weight loss

 The Mathematics of Weight loss 

By Bobby Neal Winters

Since Halloween of last year, I have lost just shy of 70 pounds. I’ve used a commercial cell phone app that I am not going to name in print, but if you want to know, and you meet me in the street, I will be happy to tell you.

In the course of losing this weight, I’ve learned something of the mathematics of weight loss, and because I am a math teacher--and that’s the way we are--I would like to share this with you.

Here is the basic working fact: Every pound of fat contains about 3500 calories.  I only have that number from the Internet, so there is probably some error in it, but it’s a nice round number so let’s use it with the understanding that it’s probably not exact.

You lose weight by “burning” more calories through metabolic activity than you take in through eating.  That is just a fact.  So, for the sake of argument, if you burn 500 more calories a day every day than you take in for one week then you will lose one pound of fat.  

That sounds simple but there are some problems.  A big one is that this weight loss can be masked.  You see your body weight is more than just fat.  In addition to the fat you are trying to lose, you have muscle and bone and water and poop.  (I was going to refer to poop as “the contents of your alimentary canal” which is accurate, but it’s just too unwieldy.) The weight of your muscle and bone are going to be more stable; the other two, less so.

When you start eating less, the weight of your poop goes down.  You take in less of it, so it weighs less.  By way of contrast, the amount of water in your body can vary wildly from day to day.  When I started my diet, my weight plummeted because I drastically reduced my carbohydrate intake. Carbs make you retain water and I lost the bloat quickly.

However, as I weighed every stinking day, I noted that my weight would go up and down more quickly than whatever amount of food I was eating would warrant. This was because of eating more salt (which causes water retention) one day than the next or because of eating more soluble fiber which causes your poop to hold more water.

If you are eating only a tiny amount of food and your weight goes up by three pounds overnight it can have a horrible affect on your morale.

In mathematical terms, water weight is a random variable that adds uncertainty to the trend.  You might erroneously believe that drinking less water is the answer, but processing water burns a certain amount of calories, so giving up water is counter productive.

I dealt with this by weighing every day in light of this uncertainty and looking only at the weekly average of my weight. 

There are two main practical issues that arise in connection with this method and they are obvious: Knowing how many calories you are taking in and knowing how many you are burning.  

For the second of these, I’ve got a watch and a cell phone that track my activity and they are in close agreement with each other.  When I do nothing all day long, I burn about 2000 calories a day. On an active day, I burn about 3700. Most days I burn about 3000, give or take.

People think that my walking has caused me to lose weight.  It helps: My daily two-mile walk burns a bit more than 400 calories.  But just “being active” helps more than any particular activity.  Yard work burns a tremendous number of calories.

My cell phone does a wonderful job at tracking my calorie in-take as well. I’ve got an app that has a large database of foods and their associated calories.  I log everything like the obsessive lunatic that I am.

I eat anything I want to, but I keep within a calorie budget of from 1800 to 2000 calories a day. (My app will let me eat more if I move around more; it’s a conspiracy.)  Given this, butter is my enemy.  It tastes good, and I love it, but it has a high ratio of calories for its size.  I limit myself to one or two teaspoons of it (or margarine) a day at most. I don’t remember the last time I put sugar in anything for the same reason.

It works better if you fill yourself up with fruit and veggies. Then you can eat enough protein, fat, and carbs to survive. 

I am now at a point where I am happy with my weight, but it is kind of like riding a tiger.  How do you get off?  In my experience, there is losing weight and gaining weight; there is no maintaining weight.  To do so, you would have to match your calorie intake to your activity, exactly.  Mathematically, the probability of doing this is zero.  This doesn’t mean it can’t be done; it just means you are not going to do it by accident.

So to summarize: Keep track of the number of calories you expend; eat fewer calories than that; don’t let the water-weight fluctuations get you down; fill up on fruit and veggies. 

The result is weight loss.

Bobby Winters, a native of Harden City, Oklahoma, blogs at redneckmath.blogspot.com and okieinexile.blogspot.com. He invites you to “like'' the National Association of Lawn Mowers on Facebook. Search for him by name on YouTube. )