You may have recently seen this graphic depicting general changes in American caloric intake from 1970 to 2005. Take a look if you haven’t. The graphic is very nice visually, but while it accurately portrays USDA data, it’s also inadvertently misleading. USDA’s own categories (shown in the graphic) are very broad and general, but the USDA dataset also includes a more detailed page for each of the categories. And it’s in those details that the trends and changes in the American diet really start to become apparent.
The infographic suggests that fats, with some contributions from grains, sugars, and meats, have accounted for the largest share of extra calories in our diet. But in the details, a few things stand out: First, the fat increase (no surprise here) does not reflect any increase in traditionally-demonized saturated/animal fats, but in vegetable oils and shortening. While the infographic shows a modest increase in sugars (50ish calories), the detailed data reveal a sizable rise in corn-based sweeteners. As for meats, the increase is largely attributable to a rise in poultry consumption, not in often-demonized red meat. These details matter, because the years 1970-present (especially starting in the mid-80s) are also the years obesity in this country has increased dramatically, and too many people still blame the wrong parts of our diet.
I’ve created a slightly-more-rudimentary set of graphics depicting the data from 1970, 1975, 1980, 1985, 1990, 1995, 2000, and 2005 with key details. They’re busier than I’d like, and bar graphs, which I’ve used in the past, show these data better, but I wanted the shapes to correspond to the original graphic, with more detail added. Keep an eye on which sweeteners and fats increase during this period, and which do not. Also, note that much of the dietary increase can be traced back to grains: grains themselves, grain/seed oils, corn sugars and even (although not depicted here) grain-fed meat. Mmm, corn.
(Caveats: the USDA data are not perfect. Some of the fluctuations year-to-year may reflect changes in data collection methods, and the data are themselves somewhat estimated. Also, these are population-level data, which limits the conclusions we can draw about individual health. However, the increase in certain ingredients is of such a scale that it is absolutely worthy of our attention.)
Average daily per capita calories from the U.S. food availability, adjusted for spoilage and other waste
Images are original and may be shared freely with attribution. Data source: USDA/Economic Research Service. Data last updated March 15, 2008. Image inspiration from the infographic cited above; please cite that too if sharing.
If you want the original jpegs of these images, send me an email. WordPress resizes these for the post, but the originals make it a bit clearer that the whole-diet circle is also growing. Although, to be fair, I don’t think the general increase in calories in our diet is what matters. Eating more can actually be an effect, and not just a cause, of obesity, as hormones like leptin, which should normally help the body regulate weight and appetite, cease to function properly. Plenty of cultures have thrived on high-calorie, high-fat diets. I’m more interested in what calories we’re eating than how many.