Food is Fuel (and it’s not)

[Listen to an audio version of this blog here.]

If you’re a person who’s halfway concerned with health or fitness, you’ve likely heard the phrase “food is fuel.” Maybe you’ve seen in on a magazine or plastered cheaply to the dingy wall of your local LA. Fitness. You may have even thought, “what a useful way to think of food!” Calories in, calories out, or something. The comparison of the human body to a car, let’s say, is as convenient as it is unsurprising. Put quality gas in your car and it’ll run well. Put quality food in your body and it’ll run well, too. If you run out of gas, your car won’t work. If you’re under-nourished, your body won’t work. And if you over-fuel your car, you’ll end up standing in a puddle of gasoline, which is sort of where the metaphor breaks down (ha).

The largest (most annoying) problem with the food-is-fuel mindset is that living organisms aren’t machines. We’re not that simple, unfortunately. Our bodies are incredibly complex, self-regulating, and dynamic beings. If you’re like me, you may have spent a lot of time doing “calorie math:” counting how many calories you eat (or estimating since getting exact calorie counts is nearly impossible), and estimating how many calories you expend. I counted calories for so long that I know how many calories are in nearly any common food item. I could even closely guess the calorie counts for restaurant foods or take-out items. And throughout my years of calorie counting, I lost, gained, and maintained weight. Once I stopped, I maintained my weight with little to no effort for years. I still am.

If food were just fuel, the oversimplified world of calorie counting would work more often than it does. And since what we eat isn’t necessarily what we absorb, the act of calorie counting is even less reliable. But I’m no expert in the science of nutrition. My last dietitian was of the “set weight” camp, which is essentially a theory arguing that our bodies try to maintain a weight within a preferred range. This theory is proven in some ways; many people stay within a more or less small range of body weight throughout their adult life. Set point theory recognizes that body weight is the product of genetic effects (DNA), epigenetic effects (heritable traits that do not involve changes in DNA), and the environment. The idea is that if you don’t excessively…