Dr. Osama Hamdy, at the Joslin Diabetes Center in Boston, offers a bit of history that might offer an explanation. (Correlation doesn’t mean causation, I know. I just think this is interesting.)
Writing for the Joslin website, Dr. Hamdy says that in 1977 the Select Committee On Nutrition and Human Needs of the U.S. Senate recommended that people increase their carbohydrate intake to 55 to 60 percent of the total caloric intake, while reducing fat consumption from approximately 40 percent to 30 percent of the total daily calories.
That recommendation led to the familiar food pyramid where grains were at the base. Hamdy writes:
What has been aptly described as a “national nutritional experiment” contributed, as we know now, to the increased prevalence of obesity. And, contrary to the main aims of the recommendations, the prevalence of type 2 diabetes — and cardiovascular disease — went up significantly.
Hamdy continues, and offers some fascinating history on diabetes treatment. If you need that link again, here it is.
But think about it this way: In the 70s, some (well-meaning) politicians tried to manipulate what people eat, and possibly launched the diabetes epidemic. In essence, they created an abnormally high incidence of diabetes.
But in the last 10 years or so, Americans have been returning to a more “normal” level. We’re rethinking the role carbohydrates play in our diet. We’re eating fewer carbs, not just because we’re worried about our pancreases, but because we want to be healthier.
The abnormal high is not regressing to the mean, as my sabermetric friends might say. Maybe not, but like I said, I just think it’s interesting.