Over the last 20 years, Americans have become increasingly aware that their diet plays a significant role for their health.

They also have become more disillusioned about the nutritional quality of the foods they are actually eating.

Despite of these changes in awareness, most people’s eating habits have largely remained unchanged and the obesity crisis has worsened. These are the findings of a study report issued by the Economic Research Service of the U.S. Department of Agriculture (USDA).

The objective of the study was to see how Americans are responding to the stepped-up educational efforts by the government and advocacy groups to improve the nutritional health of the public. For this purpose, researchers compared data from two surveys that were conducted between 1989 to 1991 and 2005 to 2008.

“Although the actual healthfulness of diets has not changed much in the last 15 years, there has been a large and significant decrease in the percentage of Americans who rate their diets as excellent or very good,” said the report. “These changes provide a snapshot of consumers’ increased dietary realism and, perhaps, receptiveness to dietary guidance, and they also suggest the possibility that a changed information environment has affected consumers’ perception.”

The comparison of the two surveys clearly shows that a significantly higher percentage of people who were asked to rate the quality of their diets grew more pessimistic over time. 8.6 percent (down from 13.2) were inclined to call their diet “excellent” and 23.3 percent (down from 27.8) thought it was “very good.” The percentage of those who considered their eating habits as “good” stayed roughly the same – 40.7 percent (up from 39.3).

The researchers concede that an “optimistic bias” about their diet still prevails among Americans. While nutrition experts have learned a great deal about the nutritional quality (or lack thereof) of the typical American diet, most consumers’ perception remains inaccurate. Our diets continue to be too high in calories, fats (especially saturated fats), sodium and added sugar. They are also too low in fiber, whole grains, fresh vegetables and important micronutrients, according to the report. The reason is not that people willfully ignore the dietary advice they’re given. They just misjudge their own actions.

Still, the overall rise in awareness is encouraging. Especially overweight people seem to realize more that their eating habits wreak havoc on their health. Among overweight people, the percentage of those who rated their diets as “excellent” or “very good” declined by 12 points since the first survey.

The researchers also looked at other data connected with diet. For example, they found a significant relationship between household income and diet quality perception. Those who believed their diets to be “excellent” or “very good” were on average financially better off than those who considered their diets as “poor.” The dramatic rise of food prices in recent years has certainly contributed to this discrepancy, although to what degree has not become altogether clear in this study.

Lack of access to healthy food resources in some rural areas and low-income inner-city neighborhoods seems to be a remarkably insignificant factor. The so-called food deserts, where travel time to a supermarket or grocery store exceeds 15 minutes, did not affect diet choices as much as previously thought.

More important was the fact that consumers eat most of their meals away from home. Home-cooking and eating together as a family are rapidly becoming a thing of the past. Again, the percentage of people recognizing these trends as a potential problem is increasing, but there is little effort or even knowledge how to make the necessary changes to reverse them. Remarkably, those who rate their eating habits as Poor spend on average a larger fraction of their food budget on restaurant food than those who say they have healthier diets.

Clearly, this report does not unveil any great secrets. Most of its observations are unsurprising. Still, one can take comfort in the thought that the information given to the public seems to register, even if that does not (yet) lead to decisive action. We can only hope there will be a tipping point in the not so distant future.

Timi Gustafson R.D. is a clinical dietitian and author of the book, “The Healthy Diner – How to Eat Right and Still Have Fun”, which is available on her blog, “Food and Health with Timi Gustafson R.D.” http://www.timigustafson.com, and at amazon.com. You can follow Timi on Twitter http://twitter.com/TimiGustafsonRD and on Facebook.