We’ve been told countless times that the availability of fast food is one of the drivers of obesity in the United States.
We all know the nutritional content of fast food is not what most of us would consider optimal. It’s loaded with carbohydrates and all kinds on nasty vegetable fats and trans fats. So it makes sense that more fast food restaurants in a given area would correlate with an increased incidence of obesity.
But, as I never tire of saying, correlation is not causation.
The charts below from the United States Department of Agriculture Economic Research Service would seem to show that rates of obesity in the United States are greater where there are fewer fast food outlets and less in the areas of greatest fast food concentration.
I wrote a post on observational studies a while back because I got tired of people asking me about studies that surface almost daily showing eating meat causes colon cancer or saturated fat causes heart disease. Virtually all of these studies are observational studies, and I wanted something I could refer to to show that these kinds of studies don’t demonstrate causation. They demonstrate only correlation. Which is good only for designing a real study to try to prove causation.
I got so wrapped up in focusing on the correlation-isn’t-causation theme that I forgot to mention something extremely important. Though correlation does not mean causation, the opposite, the lack of correlation probably does imply lack of causation.
Taking the above graphs at face value, you would have to say that fast food availability probably doesn’t cause obesity.
As anyone who reads this blog regularly should know, I am no proponent of fast food. I think the best thing people can do for their health is to spend more time in their own kitchens. Only then do they have full 100 percent control of what goes into the food they prepare.
As I wrote in a previous post, people who dine out at restaurants, even high-end restaurants, get a lot of bad fats they hadn’t bargained for. And since the number of people eating one of more meals out daily is at an all-time high, it’s no surprise that obesity is at an all-time high.
Adult obesity chart
Fast food restaurant availability chart
Obesity vs fast food availability