Diet Quality and Food Consumption: Dietary Patterns, Diet Quality, and Obesity

Overview Background Who Eats What, Where, and How Much? Food Away From Home Dietary Patterns, Diet Quality, and Obesity Dietary Trends from Food and Nutrient Availabilty Data Nutrition Information, Education, and Labeling Food Demand Analysis Health, Food Consumption, and the Agricultural Sector Recommended Readings Recommended Data Recent Research Developments Related Links

Access to Affordable and Nutritious Food: Measuring and Understanding Food Deserts and Their Consequences

Dietary patterns and diet quality

ERS examines the role of economic incentives in food choices and, in turn, how these choices affect diet quality and health. Food choices are influenced not only by prices and income, but also by family structure, time constraints, psychological factors, nutritional information, and Federal food and nutrition assistance programs, such as the Food Stamp Program. Understanding how economic and behavioral factors influence eating behavior is key to developing a solution to the rising rates of obesity in the United States.

Increasing U.S. consumption of fruits and vegetables has been a major theme of Federal dietary guidelines for over a decade. A diet rich in fruits and vegetables is associated with higher intakes of key nutrients, such as folate, potassium, and vitamins A and C. Because these foods tend to have fewer calories per serving than other foods, they can also play an important part in reducing incidence of overweight and obesity (see “Understanding Economic and Behavioral Influences on Fruit and Vegetable Choices”). Yet, despite clear health benefits and consistent Federal recommendations, most Americans fall short of their recommended fruit and vegetable intake.

To better understand the reasons for the persistent difficulty in increasing produce consumption, ERS has published a series of research briefs to provide information on the economic, social, and behavioral factors that influence fruit and vegetable consumption (see “Understanding Fruit and Vegetable Choices—Research Briefs”). Key findings are:

• Individuals with higher incomes tend to purchase more fruits and vegetables
• The cost of meeting dietary recommendations is surprisingly low—there are several ways to meet dietary recommendations for less than $1 a day
• Education has a more pronounced effect on fruit and vegetable purchases than income
• Consumers with more nutritional knowledge are more likely to choose a more healthful mix of vegetables, choosing more dark-green vegetables or deep-yellow vegetables and fewer fried potatoes.

ERS researchers have also produced a growing body of work that examines how socioeconomic factors affect other aspects of diet quality, such as how well an individual’s diet conforms to Federal dietary recommendations:

• Individuals who have higher incomes, have more formal education, or are older tend to choose higher quality diets (see “The Role of Economics in Eating Choices and Weight Outcomes”).
• Single parents have lower quality diets than married parents, and are more likely to skip breakfast and drink sugary beverages (see “The Role of Economics in Eating Choices and Weight Outcomes”).
• Household characteristics, such as whether a household is headed by a single, working parent, may increase the demand for convenience foods and food away from home (see “The Role of Economics in Eating Choices and Weight Outcomes”).
• Food away from home plays an increasing role in Americans’ diets, usually with negative effects on diet quality (Guthrie, Lin and Frazao, Journal of Nutrition Education and Behavior). (Contact Biing-Hwan Lin).
• Increased eating out appears to be a major factor in declining diet quality as children become teenagers.
• Acculturation and attitudes about diet and health also have a significant correlation with dietary choices.
• Traditional diets eaten by Hispanics who do not speak English are more healthful than the diets of acculturated Hispanics (see “Acculturation Erodes the Diet Quality of U.S. Hispanics”).
• Consumers’ misperception of diet quality can also have a significant impact on actual diet quality. An estimated 40 percent of individuals who prepared the household’s meals perceived the quality of their diets to be better than their calculated diet quality (Variyam et al., Journal of Nutrition Education). (Contact Jay Variyam).

Association between dietary patterns and obesity

To help address growing public health concerns about rising obesity rates, ERS research illuminates differences in dietary patterns by social, demographic, and economic factors. For example, a greater share of low-income men consumes excessive calories and has Body Mass Indices (BMIs) in the obese range than do high-income men. Among women, however, low incomes tend to be associated with high BMIs but lower caloric intakes. Determining the underlying causes of disparities between patterns of caloric intake and body fat measures across sociodemographic groups may lead to a better understanding of the causes of disparities in overweight and obesity (see “Food Stamps and Obesity: Ironic Twist or Complex Puzzle?” and “U.S. Per Capita Food Supply Trends: More Calories, Refined Carbohydrates, and Fats”).

ERS has examined the association between fruit and vegetable consumption and obesity and found a negative relationship between fruit consumption and BMI. That is, people who eat more servings of fruit each day have lower BMIs. In fact, healthy-weight (see table 1) children and adults eat significantly more fruits than their overweight and obese counterparts. Vegetable consumption, however, showed no consistent correlation with BMI. Why is fruit consumption a more accurate predictor of body weight status than vegetable consumption? The answer may lie in the way many Americans incorporate these foods into their diets.

Causes of obesity—an economist’s view

The prevalence of obesity and overweight has increased dramatically in the United States since the mid-1970s. The prevalence of overweight has tripled among children and adolescents, and nearly two of three adult Americans are either overweight or obese. Although high costs—in health, social, and economic terms—are known to be associated with obesity, how the U.S. population reached this point is less well understood. In most cases, weight gain and obesity are the result of individual choices. Examining the causes of the increase in obesity and proposed interventions under an economist's lens may help identify potential solutions to the obesity crisis.

An overview of leading health economics research on the causes and consequences of rising obesity in the United States can shed light on the issue (see “The Economics of Obesity: A Report on the Workshop Held at USDA's Economic Research Service”). This research shows how the technological changes driving modern economic growth have raised household incomes, reduced the price of food, and increased the price of physical activity. The resulting increase in energy consumption (food intake) and flattening of energy expenditure (physical activity) has tilted the weight equation in favor of a steady weight gain across all segments of U.S. society (“The Price is Right: Economics and the Rise in Obesity”).

Although the incidence of obesity has risen among all population groups, not everyone is equally at risk of becoming overweight or obese. Understanding weight differences is one way to find solutions to obesity and its associated health costs. ERS research found that weight differs among demographic subgroups, and differences in specific behaviors, health awareness, and eating patterns can be linked to weight outcomes. These results suggest that income, household composition, and formal education help explain variation in behaviors and attitudes that are significantly associated with weight outcomes (“The Role of Economics in Eating Choices and Weight Outcomes”).

Differences between adults' actual weight status and their perceived weight status show which individuals are mistaken in their self-perceptions. Women tend to make more accurate self-assessments than men but they are also more likely to overestimate their weight status—healthy-weight women are much more likely to indicate they think they are overweight, while overweight men are more likely to underestimate their weight status and think they are healthy. Mistakes in self-assessments are associated with demographic factors, socioeconomic status, and knowledge and attitudes toward diet and health. Federal information programs targeting obesity and overweight will be more likely to influence diet and lifestyle choices if the programs issue distinct messages to different subgroups.

ERS has also examined how dietary choices and attitudes toward diet and health contribute to obesity and whether those factors differ by gender (contact Biing-Hwan Lin for reprint). Findings indicate that:

• Choices and attitudes do matter, and the choices males and females make often have quite different effects on BMI.
• A male's belief or lack of belief that weight status is genetic has no influence on BMI.
• Women who do not believe that their weight is predetermined have lower BMI values than those who believe weight is genetically determined.

Can policies reduce obesity rates?

Action to combat obesity and overweight considers the many variables that influence diet and lifestyle choices. The wide range of factors affecting food choices is compounded by the incredible variety of foods and consumption opportunities available today. Lifestyle choices about diet quality and exercise also affect food choices. Because consumers are faced with nearly unlimited choice, public policy targeting specific foods or lifestyle choices could have surprising unintended consequences.

ERS has examined some of the potential intended and unintended consequences of three widely discussed obesity policies—nutrition labels in restaurants, taxes on snack foods, and restrictions on food advertising to children—with a focus on the likely effect of each program on producer and consumer incentives and on health outcomes. An apparently straightforward policy proposal can have surprising effects that would dampen the policy’s success in reducing overweight and obesity: mandatory nutrition information at fast food restaurants could lead to reformulations or price promotions that do not necessarily contribute to more healthful diets; taxes on snack foods could lead some consumers to substitute equally unhealthy foods for the taxed food; and restrictions on food advertising could ultimately lead to lower prices for food subject to the restrictions. (“Obesity Policy and the Law of Unintended Consequences”).

Can psychology help the dismal science?

To better understand why so many individuals choose diets and lifestyles that lead to obesity and ill health, economists are increasingly looking to psychology for answers. And for good reason—findings from behavioral and psychological studies indicate that people regularly behave in ways that contradict some basic economic assumptions. Human responses to prices and changes in income, for instance, are not cut and dry. Experimental studies of how consumers pay for various goods and services (e.g., cash versus credit, flat rate versus pay per use) show that payment options influence consumer choices. Time preferences are not solidly fixed either. The tradeoffs individuals make between now and the future fluctuate with situations, stress, and other distractions.

Behavioral experiments also reveal surprising findings about how individuals use and process information. Each day, people make thousands of decisions—Should I hit the snooze button once or twice? Do I have time to eat breakfast at home? If so, what should I have and how much should I eat? Rather than brood over each and every quotidian task (and make it to work on time), people tend to use simple rules of thumb. Given the sheer volume of information needed to be processed daily, this is an efficient solution. But it can lead to systematic reasoning errors that, again, become more likely when someone is distracted or under stress.

Incorporating such idiosyncrasies into economic analysis of consumer behavior can expand the understanding of motivating factors behind food choices and health outcomes. This can help in the design of new ways to encourage all people to choose more healthful diets (see “Could Behavioral Economics Help Improve Diet Quality for Nutrition Assistance Program Participants?” and “Insidious Consumption: Surprising Factors That Influence What We Eat and How Much”).