USDA Economic Research Service Briefing Room
" "  
Link: Bypass USDA Left navigation.
Search ERS

Browse by Subject
Diet, Health & Safety
Farm Economy
Farm Practices & Management
Food & Nutrition Assistance
Food Sector
Natural Resources & Environment
Policy Topics
Research & Productivity
Rural Economy
Trade and International Markets
Also Browse By


or

""

 


 
Briefing Rooms

Diet and Health: Recent Research Developments

Promoting healthful diets is a central goal of Federal nutrition policy, which is encapsulated in the Dietary Guidelines for Americans and the Food Guide Pyramid. For most people, such nutrition advice boils down to eating less of some foods and dietary components (such as sweets, sugars, refined grains, and saturated fat) and more of others (such as whole grains, fruit, and dark green leafy vegetables). However, this advice is more easily given than taken. Keeping tabs on your diet and portion sizes can get complicated, even for meals prepared in your own kitchen, and becomes more difficult still when it comes to that fast-food lunch, dinner at a fine restaurant, or the pizza delivered to your front door.

A 1996 survey by New York University and the Center for Science in the Public Interest found that trained dietitians underestimated the calorie content of five restaurant meals by an average of 37 percent and the fat content by 49 percent. If nutrition experts have such difficulty assessing the nutrients in their diets, imagine the difficulties of the general public. Campaigns to promote healthful diets will be less successful if people misperceive the quality of their diets. Nutrition educators, dietitians, and public health professionals will be one step ahead if we can assess to what extent consumers misperceive the quality of their diets. An added plus is that people's accuracy in assessing their dietary intakes should serve as an indicator of how successfully existing nutrition guidance is being used and understood.

40 percent of household meal planners/preparers are dietary optimists, 40 percent are dietary realists, and 20 percent are dietary pessimists.ERS researchers have used USDA's 1989-90 Continuing Survey of Food Intakes by Individuals (CSFII) and the Diet and Health Knowledge Survey (DHKS) to look at people's perceptions of their dietary intakes as compared with their actual intakes measured from 24-hour dietary recalls. Our study shows that 40 percent of household meal planners/preparers are dietary optimists—that is, they rate their diet quality to be better than it actually is. The same proportion are dietary realists—they accurately rate their diet quality. The remaining 20 percent are dietary pessimists—they perceive their diet quality to be worse than it actually is.

These percentages highlight the challenges facing successful nutrition-guidance policies. From a nutrition-guidance perspective, people who have poor diets but who believe their intakes to be healthful—our optimists—present a special area of concern. These people may be unaware that their current nutritional intake could be detrimental to their health, and there is no reason to expect them to change their eating habits without further intervention. The optimists could benefit from additional nutritional education, especially if they are somehow alerted to the health consequences of their actual diets, and the fact that they are presently acting under false impressions.

The realists—those who correctly assessed their diets—were comprised of 33 percent who had diets that were poor or needing improvement and 7 percent who had diets that were of good nutritional quality. The realists with poor diets raise questions about what would motivate them to change their eating habits. Many considerations, not just the nutritional value of food, affect dietary choices. These consumers might be more responsive to nutritional guidance that alters their perception of what "healthy eating" entails by addressing their concerns about the convenience, affordability, and flavor of healthier diets.

From a practical standpoint, persuading realists with poor diets to change their eating habits could prove to be a costly proposition. The members of this group are already aware that their diet quality is less than healthful and are perhaps reluctant to do anything about it. Alternatively, the optimists may be willing to eat more healthfully if they realize their dietary misperception, and they might be more receptive to nutritional advice. Targeting information efforts toward the optimists might offer a higher return from an investment of limited nutrition-education resources.

The likelihood of household meal planners/preparers being falsely optimistic about their diet quality is associated with their sociodemographic profiles. A greater share of men tend to be optimists compared with women. Both the youngest (ages 18-25) and the oldest (66 and older) age groups are less prone to misjudge their diet quality compared with adults ages 26-45. The difference in dietary misperception is minor among Hispanics, non-Hispanic Whites, and non-Hispanic Blacks. In addition, the tendency to overestimate diet quality increases with the level of household income and the level of educational attainment. The strongest association of false optimism about diet quality is with a person's own perceived health status. Those who believe that they are in excellent health also tend to view their diet quality as good when in fact it is not.

This piece is part of a larger paper, "Consumer misperceptions of diet quality," published in the Journal of Nutrition Education, vol. 33, issue 6, pp. 314-321. For a reprint of the complete article, please contact Jay Variyam (202) 694-5457.

 

Relative distribution of optimists among sociodemographic groups. The likelihood of household meal planners/prepapers being falsely optimistic about their diet quality is associated with their sociodemographic profiles. A greater share of men tend to be optimists compared with women. Both the youngest (ages 18-25) and the oldest (66 and older) age groups are less prone to misjudge their diet quality compared with adults ages 26-45. The difference in dietary misperception is minor among Hispanics, non-Hispanic Whites, and non-Hispanic Blacks. In addition, the tendency to overestimate diet quality increases with the level of household income and the level of educational attainment. The strongest association of false optimism about diet quality is with a person's own perceived health status. Those who believe that they are in excellent health also tend to view their diet quality as good when in fact it is not.

 

For more information, contact: Jay Variyam

Web administration: webadmin@ers.usda.gov

Updated date: August 23, 2004