John Y’s Musings from the Middle: The Mathematics of Dieting

The mathematics of dieting (or the value of a rationalizing mind)

Apparently–and this is important if you didn’t learn this in school–addition and subtraction; multiplication and division all can have nuanced exceptions apply to their normal functions when calculating caloric intake.

For example, let’s say you buy a pastry at Starbucks that you know has 400 calories.

For dieting purposes that is potentially 300 calories you will need to record for yourself if you eat the entire pastry (because you aren’t really exactly sure it’s 400 calories and it’s a smaller than usual looking pastry–and you are just trying to be honest with yourself).

However, if you only eat half the pasty, that only counts as about 100 calories (not the usual 150 or even 200 you might assume would apply using “regular non-dieting math.”

Why?

You look at the pastry and feel you ate the “smaller half.”

But, if you come back to the pastry and decide to eat 3/4ths of it (and not just 1/2), you must add another 10 calories (because the math has gotten so complicated and hard to remember that it’s OK to use shorthand at this point). So, you eat another 1/4 of the pastry and duly note the additional 10 calories. (The fact that it is 1/4th of the “bigger half” isn’t necessary to factor in at this point because you really forgot about this small fact anyway.)

And if you decide a few minutes later, “Screw it , I’m eating the whole thing” and pop the last tiny morsel in your mouth (or final 1/4 of the pastry), you will have to make yet another adjustment. Since you will recall that you just added 10 calories from eating an additional quarter of the pastry a few minutes earlier–and since you have to remain mathematically consistent— you must add another 10 calories for the final quarter of the pastry.

At this point, all you can remember is that you just added 10 calories for eating the final quarter (1/4) of the punier than usual pastry–and can’t recall what the old total calories calculation was to add to.

But that’s the beauty of math. You don’t have to remember. There’s a shortcut. If you know that one quarter (1/4th) of the pastry is 10 calories, you can be sure that the entire pastry (4/4ths) is exactly 4 times that number–or 40 calories.

So, write down 40 calories for eating that entire Starbucks pastry that was really 400 calories.

This is why so many people fail at their diets.

It not only takes willpower to succeed dieting. But you have to be really good at math, too.