Obesity in America
Nutrition, Obesity January 29th. 2008, 6:50pm
A startling map of obesity in America, and how is has increased exponentially in the last 20 years:
CNN’s Map of Obesity in America
Epidemiologists set the bar for obesity at a BMI of 30. BMI stands for “body mass index,” and it is a measure of divergence from optimal weight. To calculate a BMI value, you divide an individual’s weight (kg) by the square of their height (m2).(1) To put a BMI of 30 into perspective, a 5′5″ female would weigh 180lbs, and a 5′10″ male would weigh 209lbs. I gave the average heights for adult men and women in the US, but, in fact, the BMI calculation is independent of sex, body frame, musculature, etc. It is, therefore, a rather crude metric for estimating obesity rates, as the only determining factors are height and weight. I.e., you could be super jacked, but have a BMI that technically places you in the overweight range.(2) However, as the ratio of jacked:fat in America is approximately 0.0001, BMI is probably a reasonable indicator of America’s waistline, when averaged over a population.
Well enough about BMI. The bottom line is that America is getting extraordinarily fat, and the obesity epidemic is spreading at an alarming rate, as the CNN map demonstrates. Here is, I believe, the most provocative way of summarizing the data from the figure: in 1991, there were only 4 states with obesity rates exceeding 14%; 15 years later, there were 50. That’s every single state in the nation. Moreover, in West Virginia, Mississippi, and Alabama, practically 1 in every 3 people is obese.
Now here’s a quick lesson about micro-evolution: it doesn’t happen in 15 years. The people living in 1991 had practically the same basal propensity for weight gain as those in 2006. It is true that during those 15 years, the US population grew by about 20% (~250 million in 1991 to ~300 million in 2006), but unless only the adipose-prone were procreating during that time, we do not have much reason to believe that America, despite being larger in number, should be larger in size.(3)
But we are:
BMI distribution change in men and women (image courtesy of JAMA)
This figure depicts how BMI has changed over time. The two populations compared come from data collected between 1988-1994 and 1999-2000. One can see that, in addition to the increase over time of the median/mean of the probability density function for BMI, the distribution also flattens out in a right-skewed manner. This fact indicates that people are not only getting larger, on average, but that the incidence of ‘morbid’ obesity is increasing at an even faster rate.
So the question is, why has America suddenly become the gravitational epicenter of the universe? I noted earlier that we shouldn’t expect that something in the gene pool is to blame. The reason, therefore, must be environmental. I will cut right to the chase: we are eating too much, way too much, and way way too much of the bad stuff. Between 1960 and 2000 the average pasta serving at a restaurant almost doubled.(5) The average dinner plate size has grown by 50%, from about 8″ to 12″.(6) Moreover, our diets are filled with “empty” calories from sweeteners, most notably in beverages, but also in many other foods. Finally, as if it needed to be mentioned, McDonalds has served so many people that they’ve stopped counting on their signs.
The one commonality about the environmental issues I just rattled off is that they are all consumer-driven. People frequent the restaurants with the bigger servings. People buy the foods with the added sugars. People go to McDonalds to get fat… wait, scratch that last one, it didn’t fit.(6) The point is, consumers choose what, and how much, they eat, and consumers drive the market. So let’s demand a change, because bigger is not better, Texas included.
References:
(1)
(2) ACJIII
(3) I should inform you, however, that the US Hispanic population grew by 100% between 1991 and 2006, from ~22 million to ~44 million, and studies have demonstrated that obesity rates are higher within the Hispanic population than in the general US population.(4)
(4): An (unusually) straight-forward scholarly paper about obesity rates in the 90s.
(5)
(6) Source is questionable
(7) Pun intended.
January 29th, 2008 at 10:00 pm
In my Experimental Television class, one of the episodes we are producing is on the topic of “vices.” When you think of vices, generally drinking, smoking, gambling, etc come to mind. Someone brought up the point that while people can be very quick to warn a smoker that their habit is unhealthy, few do the same when they see someone eating fast food.
I think that really strikes it at the core. It’s not a matter of educations–people know fast food is bad for you. The problem is that it’s socially accepted. It will be interesting to see in 30 years if fatty foods have gone the way of cigarettes. People will still eat it, but we’ll look back and, with a chuckle, remember when they served curly fries, soda, and hot dogs in the school cafeteria. Tighter regulations on public school food is already a reality, and that’s spreading outward in life to new regulations like the trans fat ban in NY and Philadelphia.
But I don’t think it should be any surprise that obesity is what it is today. Genetics surely have little to nothing to do with it. It’s simply the way our culture has evolved. Where we once had stay-at-home wives and healthier home cooked meals, we now have dual-income families and less time to be healthy. I’m personally having that problem this semester–I don’t get home until after 8 most days, tired and hungry. Unfortunately fast and healthy just don’t go together. At least not without a hefty premium most aren’t willing to pay.