|
|
||||||||
ORIGINAL RESEARCH COMMUNICATION |
1 From the Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Division of Nutrition and Physical Activity, Atlanta, GA (JHL, HMB, LKK, MKS, JDS, and BCT), and the Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA (JHL and BJR)
2 The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the funding agency.
3 Supported in part by the National Institutes of Health grant R37DK039177 (BJR) and by an appointment to the Research Participation Program at the Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Division of Nutrition and Physical Activity, which was administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US Department of Energy and the Centers for Disease Control and Prevention (JHL).
4 Reprints not available. Address correspondence to JH Ledikwe, The Pennsylvania State University, 226 Henderson Building, University Park, PA 16802. E-mail: mvh111{at}psu.edu.
| ABSTRACT |
|---|
|
|
|---|
Objectives: A representative US sample was used to determine whether dietary energy density is associated with energy intake, the weight of food consumed, and body weight and to explore the influence of food choices (fruit, vegetable, and fat consumption) on energy density and body weight.
Design: A cross-sectional survey of adults (n = 7356) from the 19941996 Continuing Survey of Food Intakes by Individuals and two 24-h dietary recalls were used.
Results: Men and women with a low-energy-dense diet had lower energy intakes (
425 and 275 kcal/d less, respectively) than did those with a high-energy-dense diet, even though they consumed more food (
400 and 300 g/d more, respectively). Normal-weight persons had diets with a lower energy density than did obese persons. Persons with a high fruit and vegetable intake had the lowest energy density values and the lowest obesity prevalence.
Conclusions: Adults consuming a low-energy-dense diet are likely to consume more food (by weight) but to have a lower energy intake than do those consuming a higher-energy-dense diet. The energy density of a variety of dietary patterns, including higher-fat diets, can be lowered by adding fruit and vegetables. Our findings support the hypothesis that a relation exists between the consumption of an energy-dense diet and obesity and provide evidence of the importance of fruit and vegetable consumption for weight management.
Key Words: Energy density obesity weight management food patterns fruit and vegetables Continuing Survey of Food Intakes by Individuals CSFII
| INTRODUCTION |
|---|
|
|
|---|
Energy density refers to the amount of energy in a given weight of food. Foods with a low energy density provide less energy per gram than do foods with a high energy density. Studies indicate that people tend to consume a fairly consistent weight of food over the course of a few days; therefore, the consumption of low-energy-dense foods that contain less energy per gram may decrease overall energy intakes (4). Multiple laboratory-based studies have confirmed that people consume less energy when they are presented with foods that have a lower energy density than when they are offered similar foods with a higher energy density (5-10). Few studies, however, have investigated whether energy density influences total energy intake in free-living persons, and even fewer studies have investigated associations with weight status (11, 12).
To develop effective dietary strategies for weight management, we need to understand how energy density and weight status are influenced by food choices. Consuming water- and fiber-rich foods, such as fruit and vegetables, is one strategy for decreasing the energy density of the diet, because water and fiber contribute weight to food with limited energy (13). Another strategy is to limit high-fat foods, because fat (9 kcal/g) adds substantially more energy to food than does water (0 kcal/g), fiber (1.52.5 kcal/g), carbohydrate (4 kcal/g), or protein (4 kcal/g) (13). Because fat is highly palatable, however, extreme reductions in fat intake may be difficult for some people to maintain. Whether a high consumption of water-rich and fiber-rich foods can substantially lower the energy density of a diet that is higher in fat has yet to be determined. To better understand strategies that patients could use to lower the energy density of their diet, we need information on how the consumption of different amounts of fruit and vegetables and of fat is related to energy density and weight status (14, 15).
The purpose of this investigation was to use a nationally representative sample of noninstitutionalized adults to test the hypothesis that the energy density of the diet is associated with total energy intake, the weight of food consumed, and body weight. We also explored the influence of fruit, vegetable, and fat intakes on energy density and body weight.
| SUBJECTS AND METHODS |
|---|
|
|
|---|
|
Results of an earlier study indicated that the inclusion of beverages when calculating the energy density of a diet may diminish associations with outcome variables because of increased day-to-day variance within individual respondents (20). Therefore, energy density values were calculated based only on food intake, excluding all beverages. As described previously (20), total energy intake from the food consumed for each of the 2 d was divided by the total weight of the food reported. Values for energy density from day 1 and day 2 were averaged to derive a mean value for each participant. Because beverages are a substantial source of energy for some people, energy intake from beverages was also examined as an outcome, even though beverages were not included in the calculation of energy density.
Body mass index (BMI) values were computed as weight (kg) divided by height squared (m). Weight and height measures were self-reported. Participants were classified by BMI as being normal weight (
24.9), overweight (25.029.9), or obese (
30.0) (2).
Statistical analyses
The data were analyzed by using SAS-callable SUDAAN software (release 8.02, 2003; Research Triangle Institute, Research Triangle Park, NC). Because standard definitions describing a person's diet based on energy density have not been developed, we used sex-specific tertile cutoffs to classify the diets of both men and women as having a low, medium, or high energy density. To test for differences by these 3 categories for categorical and continuous variables, we used chi-square and analysis of variance tests, respectively. Covariates included in the analyses with continuous variables included age group (2029, 3039, 4049, 5059, 6069, or
70 y), race-ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, Asian Pacific Islander, or other), region of the United States (northeast, midwest, south, or west), annual income expressed as a percentage of the poverty threshold (0130%, 131350%, or >350%), highest level of education (less than high school, high school, <4 y of college, or
4 y of college), frequency of exercising vigorously (<1 time/mo, 15 times/mo, 24 times/wk, or
5 times/wk), and current smoking status (yes or no). To explore differences by fruit, vegetable, and fat intakes, the subjects were categorized on the basis of the consumption of fruit and vegetables (<5, 59, or >9 servings/d) and fat intake (
30% or >30% of energy from fat). Estimated percentages, means, CIs, and comparisons were based on weighted observations that reflected the probability of selection, nonresponse, and adjustments following stratification. P values <0.05 were considered significant.
| RESULTS |
|---|
|
|
|---|
Men and women with a low-energy-dense diet had a lower mean intake of total energy, energy from food, and energy from beverages than did their counterparts with a medium- or high-energy-dense diet (Table 2
). The estimated total energy intake from food and beverages for men with a low-energy-dense diet was 432 kcal/d less than that for men with a high-energy-dense diet. Similarly, energy intake for women with a low-energy-dense diet was an estimated 278 kcal/d less than that for their counterparts with a high-energy-dense diet. Men and women with a low-energy-dense diet consumed an estimated 396 and 295 g/d more food, respectively, than did their peers with a high-energy-dense diet (Table 2
), and these differences were significant. In contrast, men and women with a low-energy-dense diet drank fewer grams per day of nonwater beverages than did those with a medium- or high-energy-dense diet.
|
|
|
30% or >30% of energy from fat/d) were analyzed. There was a significant interaction between fruit and vegetable intake and fat intake (P < 0.03); therefore, subjects were stratified into subgroups based on both of these variables. The energy density of food patterns stratified by intake of fruit and vegetables and fat intake are presented for men and women combined in Figure 2
|
30% of energy from fat) that was rich in fruit and vegetables (>9 servings/d) had diets with the lowest energy density; they were followed by those with a high-fat diet that was rich in fruit and vegetables (>9 servings/d). Dietary energy density was lower for persons with a high-fat diet and a high consumption of fruit and vegetables than for persons with a low-fat diet and a low consumption of fruit and vegetables.
Persons with a high-fat diet and a low intake of fruit and vegetables (<5servings/d) had the highest prevalence of obesity (Figure 3
). Within both of the fat intake categories, the prevalence of obesity was lowest for persons with a diet high in fruit and vegetables (9% in the high-fat group and 6% in the low-fat group).
|
| DISCUSSION |
|---|
|
|
|---|
Studies in free-living Mediterranean (21), Chinese (22), and French (23) also found that those with a diet low in energy density consumed less energy. The finding in the present study that persons with a low-energy-dense diet consumed the greatest amount of food has important implications for promoting compliance with prescribed dietary regimens. A diet plan that severely restricts the amount of food a patient consumes will likely lead to feelings of hunger and have unfavorable influences on the patient's satisfaction with the diet and long-term compliance. Positive messages that encourage people to eat certain foods, such as fruit and vegetables, have been found to be more effective for weight management than messages that restrict certain foods (24).
Although it is important to understand the relation between energy density and food intake, it is also critical to explore the relation between energy density and body weight. In the present study, those who were obese consumed diets higher in energy density than did those who were not obese. Although several studies in the literature have found lower dietary energy density values to be associated with a more favorable body weight (25-27), other studies have not supported such a relation (21, 23, 28). One potential explanation for the inconsistent findings may be that different schemes for including beverages in the calculation of energy density were used in these studies. Beverages tend to have a lower energy density than do most foods and may disproportionately influence dietary energy density values (20). Furthermore, data indicate that including beverages as part of the diet when calculating dietary energy density may weaken associations with weight status because of increased within-person variance (20). The lack of an association between body weight and dietary intake in some studies may be due to the cross-sectional nature of these studies if the participants did not have a stable body weight. Another potential explanation for the conflicting results in the literature is the degree to which the studies accounted for confounding variables. Stookey (22) reported that the relation between energy density and weight status was strengthened by adjustments for covariates. The present study included potential covariates, but physical activity was assessed with only one question that pertained to the frequency of vigorous exercise, which may not have been sufficient. Care should be taken in future studies to fully assess and control for possible confounding variables.
A strength of this article is that it not only examined the relation between energy density and weight status but also explored how these findings can be put into a practical context for dietary advice. These data indicate that a diet that has a low energy density does not have to be low in fat if it is rich in fruit and vegetables. Consumption of
9 servings of fruit and vegetables was associated with lower dietary energy density values as well as a lower prevalence of obesity even for diets high in fat. Although evidence in the literature showing a relation between intake of fruit and vegetables and body weight is limited, these findings support a recent review of epidemiologic studies that found a tendency for higher body weights to be associated with lower consumption of fruit and vegetables (15).
A limitation of this study is the use of self-reported measures of body weight. Data indicate that overweight persons are not only likely to underreport anthropometric measures (29) but are also likely to misreport food intakes (30, 31). Consistent underreporting or overreporting across all types of foods will likely have little influence on energy density values. However, data indicate that overweight persons may selectively underreport intakes of high-fat foods (32, 33), which could cause energy density estimations to be lower than actual values. Further work is needed to understand the potential influence of misreporting on estimated energy density values (20) as well as the consequences of shared error bias between anthropometric and dietary measures in epidemiologic studies (32). In the present study, however, the potential shared error created by underreporting of dietary measures by obese persons would likely have weakened associations between energy density and weight status and possibly led to a null finding.
Dried and fried fruit and vegetables and juices were not included when determining fruit and vegetable servings, because a recent review article (15) emphasizes the importance of attention to food preparation methods when investigating associations between food intake and body weight. Note, however, that current dietary guidelines include these items as fruit and vegetables (1). Additionally, because of the cross-sectional design of this study, inferences regarding cause and effect are limited. These data are, however, supported by findings from laboratory and clinical studies.
Behavioral changes that yield modest but persistent reductions in energy intake are likely to be critical to successful weight loss. Decreasing overall food intake as a strategy to reduce energy intake is unlikely to be successful in the current eating environment, ie, one in which large portions of energy-dense foods are common. It is preferable to make subtle changes to reduce the energy density of the diet, which will result in long-term acceptance. For example, the energy density of many popular foods, such as pizza, sandwiches, and casseroles, can be decreased by reducing the fat content and through the addition of water-rich vegetables without necessarily affecting palatability or portion size (13). Furthermore, selecting foods on the basis of a low energy density can lead to healthy food patterns, such as those consistent with the Dietary Guidelines for Americans (1) and the new MyPyramid food guidance system (18).
The energy density of a variety of different dietary patterns can be lowered, even those that are high in fat. Although a simultaneous decrease in fat intake and an increase in fruit and vegetable intake will likely have the greatest affect on energy density and body weight, this approach may not be best for all patients, particularly those unwilling to consume a low-fat diet. Because palatability and food preferences play a critical role in food selection (34), structuring dietary advice around a patient's existing dietary pattern to achieve a reduction in energy density may increase the likelihood that long-lasting dietary changes will be achieved.
| ACKNOWLEDGMENTS |
|---|
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
J. S Savage, M. Marini, and L. L Birch Dietary energy density predicts women's weight change over 6 y Am. J. Clinical Nutrition, September 1, 2008; 88(3): 677 - 684. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. L Deierlein, A. M. Siega-Riz, and A. Herring Dietary energy density but not glycemic load is associated with gestational weight gain Am. J. Clinical Nutrition, September 1, 2008; 88(3): 693 - 699. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Bes-Rastrollo, R. M van Dam, M. A. Martinez-Gonzalez, T. Y Li, L. L Sampson, and F. B Hu Prospective study of dietary energy density and weight gain in women Am. J. Clinical Nutrition, September 1, 2008; 88(3): 769 - 777. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. K Gao, S. A. Beresford, L. L Frank, P. J Schreiner, G. L Burke, and A. L Fitzpatrick Modifications to the Healthy Eating Index and its ability to predict obesity: the Multi-Ethnic Study of Atherosclerosis Am. J. Clinical Nutrition, July 1, 2008; 88(1): 64 - 69. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. A McCaffrey, K. L Rennie, M. A Kerr, J. M Wallace, M. P Hannon-Fletcher, W A. Coward, S. A Jebb, and M B. E Livingstone Energy density of the diet and change in body fatness from childhood to adolescence; is there a relation? Am. J. Clinical Nutrition, May 1, 2008; 87(5): 1230 - 1237. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Johnson, A. P Mander, L. R Jones, P. M Emmett, and S. A Jebb Energy-dense, low-fiber, high-fat dietary pattern is associated with increased fatness in childhood Am. J. Clinical Nutrition, April 1, 2008; 87(4): 846 - 854. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. L. J. Greenwood and J. B. Stanford Preventing or Improving Obesity by Addressing Specific Eating Patterns J Am Board Fam Med, March 1, 2008; 21(2): 135 - 140. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Maillot, N. Darmon, F. Vieux, and A. Drewnowski Low energy density and high nutritional quality are each associated with higher diet costs in French adults Am. J. Clinical Nutrition, September 1, 2007; 86(3): 690 - 696. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. O Fisher, Y. Liu, L. L Birch, and B. J Rolls Effects of portion size and energy density on young children's intake at a meal Am. J. Clinical Nutrition, July 1, 2007; 86(1): 174 - 179. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Murakami, S. Sasaki, Y. Takahashi, K. Uenishi, M. Yamasaki, H. Hayabuchi, T. Goda, J. Oka, K. Baba, K. Ohki, et al. Hardness (difficulty of chewing) of the habitual diet in relation to body mass index and waist circumference in free-living Japanese women aged 18-22 y Am. J. Clinical Nutrition, July 1, 2007; 86(1): 206 - 213. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. J. DeMaria Bariatric Surgery for Morbid Obesity N. Engl. J. Med., May 24, 2007; 356(21): 2176 - 2183. [Full Text] [PDF] |
||||
![]() |
J. H Ledikwe, B. J Rolls, H. Smiciklas-Wright, D. C Mitchell, J. D Ard, C. Champagne, N. Karanja, P.-H. Lin, V. J Stevens, and L. J Appel Reductions in dietary energy density are associated with weight loss in overweight and obese participants in the PREMIER trial Am. J. Clinical Nutrition, May 1, 2007; 85(5): 1212 - 1221. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. A. Mendoza, A. Drewnowski, and D. A. Christakis Dietary Energy Density Is Associated With Obesity and the Metabolic Syndrome in U.S. Adults Diabetes Care, April 1, 2007; 30(4): 974 - 979. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. K. Newby Are Dietary Intakes and Eating Behaviors Related to Childhood Obesity? A Comprehensive Review of the Evidence J. Law Med. Ethics, March 1, 2007; 35(1): 35 - 60. [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |