Fat and global warming
When I first read this article I had an odd sense of déjà vu. Then I realized why: it's not a new story! Not only that, but every time this subject has come up, the same people seem to be behind it. Ian Roberts wrote the original diatribe in 2007, he and Dr. Phil Edwards wrote a letter to the Lancet in 2008 with the same message, and now they've published a study along these same lines. The thing is, all of their research is based on the same faulty assumptions: that fat people consume more energy by eating and driving more. Even this new "study" draws conclusions based on these assumptions. For instance:
Since it can be assumed that energy expenditure is approximately balanced by energy intake, it follows that total food energy consumption increases as BMI increases.
So, we're going to assume that each step up the BMI ladder means more food consumption? There have been studies to refute this, but even if you disregard them and assume that I, with a BMI of 60+ eat THREE TIMES THE VOLUME OF FOOD as a person with a BMI of 20, what about the one in four people in the UK who are on a constant diet? What about the 45 million Americans who go on diets each year? Some of those folks must be fat, yes? So right there you can see it's ridiculous to assume that every fat person eats more than someone with a lower BMI. If it were true, the diet industry would crumble.
To estimate the GHG emissions due to car travel by each population, we assumed that all individuals with BMI < 30 kg/m2 use an average small car (e.g. Ford Fiesta) and that individuals with BMI 30 kg/m2 use a car with more internal space (e.g. Ford Galaxy). The Ford Fiesta weighs 1530 kg and produces 147 gCO2 per km, whereas the Ford Galaxy weighs 2415 kg and produces 197 gCO2 per km.
So for the purposes of this study, we're just going to *assume* that all of the skinny folks drive tiny cars and all of the fat folks drive bigger cars. What about all of the skinny SUV drivers? What about the fat folks who drive hybrids or smaller, more fuel-efficient cars? What about all of the poorer fat people who don't even have their own car and instead take public transportation?
The increase in energy expenditure with increasing body weight should prevent further weight gain in a negative feedback loop but with rising BMI people are likely to move less, particularly those who are substantially overweight
Of course this part ignores the active fat people and imagines that all skinny people are active. It also incorrectly assumes (again) that the amount of walking a person does correlates somehow with their BMI. Furthermore, when I was digging for info I came across this article that states that driving might be better for the planet than walking anyway.
So Dr. Phil Edwards and Ian Roberts, here's some advice: no matter how many times you interpret and reinterpret these data, you're still starting off with a bunch of flawed, unproven assumptions that, despite the moderate media interest, add up to nothing more than fat-bashing, sizeist nonsense. Your "research" is focusing attention on fat people instead of the actual changes that need to be made to stop global warming. Do the planet a favor and kindly knock it off.
Thanks to DC and Marilyn for the tip