Energy Equivalence

Two things that seem to be in the headlines of late: oil prices and overweight Americans. How do these things go together? Time for a fun "back of the envelope" calculation.

According to the CDC about two-thirds of American adults are overweight or obese (a BMI over 25 tags you as overweight while a BMI over 30 defines obese). Currently, nearly a third of US adults are obese. If we ignore the obese children for a moment (and that's getting harder and harder to do), that means there's somewhere around 165 million Americans who are at least overweight. Let's be really generous (kind of like current trends in clothing), and assume that the average individual in this group is 15 pounds overweight. That's about what you get for a person 5'10" tall with a BMI of 27. I suspect the average is far more, but this is good enough for our quick-and-dirty calculation. If we multiply the number of adults by the average excess poundage, and assuming that each pound is indeed fat with an energy content of about 3500 kcals per pound, and convert the total to kilojoules, we wind up with around 3.7E13 kjoules total excess energy stored in the bodies of American citizens.

Here's the fun part. A barrel of crude oil contains about 6.1E6 kjoules. Further, we import about 1.5 million barrels of crude per day from Saudi Arabia (our second largest source, Canada being first at about 2 million). If you put these together and assuming we could transform all of the excess weight hanging from our collective bodies into a useful form, we'd have about four days worth of crude imports from the Saudis. The really fun part is that, depending on how you look at it, it shows not only how fat we are as a nation, but also, just how huge is our appetite for petroleum.