An intervention study targeting energy and nutrient intake in worksite cafeterias
Introduction
The food environment has a powerful influence on eating behavior. Modifying the food environment is a novel approach for facilitating changes in eating behavior, such as reductions in energy intake that might ultimately prevent weight gain (Lowe, 2003). One such method is to reduce the energy density (ED) of foods available in a particular environment, such as a worksite cafeteria. ED, or the amount of energy in a given weight of food, influences energy intake. Dietary fat increases the ED of a food more than either carbohydrate or protein, while water decreases ED by adding weight but little or no energy. Reducing the ED of a diet can reduce energy intake without increasing hunger or producing short-term energy compensation (Ello-Martin et al., 2005, Rolls et al., 1999). When people were given diets varying in ED over the course of several days and allowed to eat ad libitum, those on the reduced-energy-dense diet consumed less energy than those on the higher-energy-dense-diet (Rolls et al., 1999). Data from several randomized clinical trials have found that reductions in dietary ED are associated with weight loss (Ello-Martin et al., 2007, Ledikwe et al., 2007, Rolls et al., 2005).
Reduced ED eating interventions can be combined with other environmental changes for weight gain prevention. Manipulating financial incentives for making particular food choices may be an effective way to modify food intake. There is preliminary evidence that the cost of food has a significant impact on food choices (French et al., 1997, French et al., 2001, Ledikwe et al., 2007). Another readily modifiable aspect of the food environment is the nutritional information provided to consumers at the point of purchase. This approach has promise but does not yet have strong research support (Engbers et al., 2005, Steenhuis et al., 2004).
This study was designed to test innovative, environmental approaches to changing eating behaviors in worksite cafeterias. After an observation-only baseline period, all participants were exposed to two environmental changes in their worksite cafeteria: 1) the ED of some foods was reduced, and 2) nutritional labels (including ED information) were provided for all foods sold in the cafeterias. One aim of the study was to determine if these environmental interventions resulted in changes in food intake over time. In addition, half the participants were assigned at random to a training and incentive program that provided specific guidance on how to reduce the ED of the diet both inside and outside of the worksite cafeteria and provided discounts on low-ED foods purchased in the cafeteria. The second aim of the study was to determine if this educational and incentive program produced greater dietary change than the ED and labeling intervention alone. The primary outcome of the study was the food choices that participants made in the cafeteria. This outcome variable was measured in a novel way: by electronically capturing food choice data continuously and automatically at the point of purchase in the cafeteria.
Section snippets
Participants and recruitment
This study took place at two hospital cafeterias in Philadelphia, PA. Eligible participants included male and female hospital or university employees between the ages of 21 and 65 years. Participants were eligible if they reported eating lunch in the hospital cafeteria at least two times each week, on average. We chose a minimum of twice a week to ensure a representative sample from Hospital A and B that would provide frequent enough data to get a sense of what participants were purchasing
Demographics and attrition
Ninety-six employees of the two hospitals volunteered to take part (mean age = 44.2; SD = 9.9). The sample was composed of 54% Whites, 39% Blacks, 3% Asian, 2% Hispanics, and 1% who reported mixed or “other” racial heritage. The average body mass index (BMI = kg/m2) of participants at the start of the study was 29.7 (SD = 6.0). Fifty-three individuals participated from Hospital A and 43 participated from Hospital B. There were 18 men and 78 women who were randomly assigned to either the EC (11 men and
Discussion
The results of this study demonstrated that relatively minor modifications to worksite cafeterias may produce improvements in macronutrient and energy intake, but that more intensive environmental changes are likely necessary to produce larger effects. Both total energy intake from purchased cafeteria foods and the percent of energy from fat in purchased foods declined significantly during the 6-month study period, but total energy intake assessed with 3-day food records did not change. The
Role of funding source
This study was funded by the National Institutes of Health (NIH) grant number 5 R01 HL073775-04 [DK02-021]. The NIH had no role in study design, collection, analysis, or interpretation of data, writing the manuscript, or the decision to submit the manuscript for publication.
Contributors
The authors' responsibilities were as follows: MRL and BJR: study concept and design; MLB, KT, MCC, and CNO: acquisition of data; MRL, MLB, KAT, and BJR: statistical analysis and interpretation of the data; MRL, KAT, MLB, MCC, and CNO: draft of the manuscript; MRL and BJR: funding; MRL, MLB, RAA, MCC, and CNO: administrative, technical, and material support; MRL: study supervision; and all authors: final approval of the version to be published.
Conflict of interest
Dr. Lowe is a member of the Scientific Advisory Board for Weight Watchers and has been a consultant to Pfizer for their development of a weight loss medication. Barbara Rolls is the author of the book Volumetrics. All other authors declare that they have no conflicts of interest.
References (25)
- et al.
The influence of food portion size and energy density on energy intake: Implications for weight management
American Journal of Clinical Nutrition
(2005) - et al.
Dietary energy density in the treatment of obesity: A year-long trial comparing two weight-loss diets
American Journal of Clinical Nutrition
(2007) - et al.
Worksite health promotion programs with environmental changes: A systematic review
American Journal of Preventive Medicine
(2005) - et al.
Undereating and underrecording of habitual food intake in obese men: Selective underreporting of fat intake
The American Journal of Clinical Nutrition
(2000) - et al.
Accuracy of energy intake data estimated by a multiple-pass, 24-hour dietary recall technique
Journal of the American Dietetic Association
(2000) - et al.
Dietary energy density determined by eight calculation methods in a nationally representative united states population
Journal of Nutrition
(2005) - et al.
Reductions in dietary energy density are associated with weight loss in overweight and obese participants in the PREMIER trial
American Journal of Clinical Nutrition
(2007) - et al.
Energy density but not fat content of foods affected energy intake in lean and obese women
American Journal of Clinical Nutrition
(1999) - et al.
The three-factor eating questionnaire to measure dietary restraint, disinhibition and hunger
Journal of Psychosomatic Research
(1985) Relaxation therapy for essential hypertension: Specific or nonspecific effects
Journal of Psychosomatic Research
(1984)