Of course, if you do a little browsing at a car dealership, you'll start to notice how much gas mileage varies between vehicles. In fact, you can even pick two similar sedans and one will average four miles per gallon more than the other. After all, there are a lot of variables that factor in to gas mileage: how many cylinders the engine has, whether it's a manual or an automatic, the weight of the vehicle and even aerodynamics comes into play.
Now, when you get the car off the lot, all of the sudden you've got even more variables added to this equation. For instance, you buy a truck that averages 15-19 miles per gallon. Load down that truck with two thousand pounds of cargo (sod, cinder blocks, ponies, what have you) and I doubt you'll be getting the full potential of gas mileage out of your vehicle. Drive 80 miles an hour up a hill against the wind and I guarantee you'll be seeing even less.
Wait. This is not a car blog, so why the heck am I talking about gas mileage? I just want to give you a minuscule taste of the variables involved in how much fuel the human body burns every day. Of course, I'm not a Mustang and you're not a Jeep, and that's kind of the point. If there are so many factors relating to gas mileage... what makes you think our bodies are any less complicated? In fact, I'd even venture to say thermogenesis in humans is waaaaay more complex than the fuel requirements of a pick-up truck.
Do you think you can guess exactly how much gas your car will use to get from point A to point B? Maybe you can get a rough estimate. You might even get all scientific and research the weather or even the weight of the passengers to try and get a more accurate guess. But in the end, it's still a guess. You might be close, but it's still a guess. And you'd probably be wrong. Maybe by a lot, maybe by just a little. But you'd still be wrong.
So why does a Google search for "daily calorie needs" yield nearly five million results? Because people like to think they can predict how much fuel the body needs on any given day. And in fact, they claim they can do it with the most rudimentary information out there. Half the caloric calculators out there only take into account weight, height and maybe a rough estimate of physical activity. It's like trying to build an iPhone
with a wooden club and a rock. It just don't work.
with a wooden club and a rock. It just don't work.Caloric Needs: The Bigger Picture
There are many other factors involved in how many calories (energy units) the body uses on a given day--thyroid health, leptin sensitivity and insulin sensitivity being among them. The body will also burn more or less depending on how much you eat. That's right. How much you eat affects how much you burn. That's why you read a lot about metabolisms screeching to a halt during dieting. And maybe you've even experienced something like this yourself (goodness knows I have).
That's because your body responds biochemically to the amount (and yes, the quality) of the food you eat. The health of all your hormonal systems--and therefore your whole self--is affected by the food you eat. That's why there have been so many interesting underfeeding and overfeeding studies out there (you can read more about those in Gary Taubes' book Good Calories, Bad Calories).
The fact is that the body works hard to maintain homeostasis, however that's defined at a given moment. That means adding or subtracting a little food here and there may not have the impact we could predict by running the numbers. The body might simply adjust in response.
When 100 Calories Isn't Really 100 Calories
Of course, we don't Google "daily calorie needs" just for kicks. Calculating caloric needs inevitably leads you to the road of counting calories--you know, weighing, measuring or at least guesstimating every bite that passes your lips. (Sounds fun, right?) Well, as neat and tidy as that sounds, it doesn't really fly in the real world. In fact, in the real world, caloric content in restaurant foods is an average of 18 percent higher than what's listed on the label (read about that here). Which is perfectly legal, because the FDA allows for a 20 percent margin of error between what the label says and what the food really contains.
So, if we can't depend on product labels, what are we to do? Do things the old-fashioned way: depend on your appetite. Of course, you can't rely on your appetite if you're scarfing down pizza made with white flour and soda filled with high-fructose corn syrup, because foods like these screw up the body's natural satiety mechanisms. And that's where real, nutrient-dense food comes in. But that's a post for another day, so today I'll leave you with this tidbit:
The body doesn't count calories. And neither should you.
And if you can't wait for more juicy information about hormones, homeostasis and the like, check out this amazing podcast interview between Jimmy Moore and Dr. Robert Lustig (yeah, the fructose guy):
‘Livin’ La Vida Low-Carb Show’ Episode 378: Dr. Robert Lustig From ‘Sugar: The Bitter Truth’ Explains Why You Don’t Need To Be On A Low-Carb Diet
This post is part of Real Food Wednesday, hosted by Kelly the Kitchen Kop and Fight Back Friday at Food Renegade.
‘Livin’ La Vida Low-Carb Show’ Episode 378: Dr. Robert Lustig From ‘Sugar: The Bitter Truth’ Explains Why You Don’t Need To Be On A Low-Carb Diet
This post is part of Real Food Wednesday, hosted by Kelly the Kitchen Kop and Fight Back Friday at Food Renegade.
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