Half Glass

Glass Half Full: Too Many Bad Carbs

Oh dear. Low quality carbs are down in the American diet, but it’s not good enough. Nutrition scientists from Harvard and Tufts say the glass is half full. We’re eating too many bad carbs. Fang Fang Zhang, a senior author of a new paper in JAMA, explains:

Although there are some encouraging signs that the American diet improved slightly over time, we are still a long way from getting an “A” on this report card.

This scolding reminds us of Eeyore’s low opinion of other animals. “No brain at all, some of them, only grey fluff that’s blown into their heads by mistake.”

A Study of Trends in Self-Reported Dietary Habits

Zhilei Shan et al studied 24-hour dietary recall data from NHANES from 1999 to 2016. These self-reports rely on human memory about food. Such self reports have their critics. But they also have staunch defenders. Regardless, nutritional epidemiologists depend on them and study them relentlessly.

Shan and his colleagues found that over time, Americans were eating fewer low-quality carbs and more high-quality carbs. They found other good trends. Plant protein and polyunsaturated fat were also going up. However, their bottom line was that people are still eating too many low-quality carbs and too much saturated fat.

A Lag Effect?

If you want another bummer to consider, take a look at this study in Economics & Human Biology. Alexander Bentley, Damian Ruck, and Hillary Fouts tell us that there’s a time lag in the effects of eating too much sugar. They say that the increase in obesity we’re seeing now is a legacy of sugar we ate in the 1970s and 1980s. The die is cast. Our goose is cooked.

Does This Help?

For almost two decades now, the buzz about bad carbs has been at a fever pitch. In that environment, we’re not surprised that people report eating less of them. That’s what they’re supposed to do now. You’d have to be an idiot to miss that point.

But all this advice about what not to do is not terribly helpful. Ask any toddler. No is a very unpopular word. This is why advertisers rely on aspirational messaging. How can we move toward healthy diets and healthier lives?

In a companion editorial, Linda Van Horn and Marilyn Cornelis offer a slightly more hopeful view. They say that the trends detected by Shan et al give reasons to believe that dietary guidance can nudge people toward better health.

We’re not so sure. Have four decades of highly politicized dietary guidelines brought us better health? We share the skepticism offered by Adele Hite. Not to the point of suggesting we should abandon dietary guidance. But we should think more critically about its effectiveness. If, as Shan et al say, our diets aren’t improving much, maybe the guidelines are ineffective.

Click here for the study by Shan et al and here for the editorial by Van Horn and Cornelis. For the press release and further reporting, click here and here.

Half Glass, photograph © Vladimir Kud / flickr

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September 25, 2019





2 Responses to “Glass Half Full: Too Many Bad Carbs”

  1. September 26, 2019 at 5:42 am, Mary-Jo said:

    In principle, I believe that dietary guidelines are helpful IF they present information that translates the science, as we know it, into dietary strategy that can help a general population obtain optimal nutrition. But, if these guidelines are influenced by BigFood, in any way, they are worthless. More, importantly, dietary guidelines are a futile charade and impotent, if the environment encourages dietary intake that makes following the guidelines extremely difficult, if not, impossible.

  2. September 26, 2019 at 7:09 am, Linn Steward RDN said:

    I think the guidelines are the problem. Especially punitive for someone like me who loves food and was used to cooking every day before beginning my nutrition studies. Have the experts who write the guidelines ever walked into a kitchen? Do they know anything about cooking? Do they enjoy eating? My eating pattern was established early on. Basically anything I wanted as long as it was intact whole food. Mostly plants but a good cheese, some heritage pork, or a gamy bird is always welcome at my table. I never realized my food choices were unhealthy however until I went back to school to study nutrition in the early 1990s. Perhaps there is a reason why my foodie friends ignore the guidelines and enjoy their meals while many of my zealous colleagues are prone to eating disorders and overweight. Maybe the guidelines have not failed us, but they certainly haven’t helped.