Introduction
Rates of overweight in the Netherlands are high. To illustrate, in 2014, 43% of Dutch men and 31% of Dutch women were overweight [
1]. Overweight is associated with the incidence of co-morbidity such as type II diabetes, cardiovascular diseases and several types of cancer [
2] which underpins the importance of targeting this health problem. Additional to the burden of disease, also healthcare spending and costs of sick leave stress the concern of the increasing prevalence of overweight and obesity [
3‐
6].
Overweight and obesity are generally the result of an imbalance between energy intake (eating) and energy expenditure (physical activity) [
7]. The current “obesogenicity” of the environment, which means an abundant availability, easy accessibility and aggressive marketing of foods, together with declines in physical activity, makes it difficult not to gain weight [
8].
A commonly used strategy in decreasing overweight is to focus on changing eating behaviors. Eating behaviors influence energy intake through choices about when and where to eat, and the types and amounts of foods chosen, including decisions about starting and stop eating [
9,
10]. Moreover, interventions with a dietary component result in weight loss [
11]. A suitable location for targeting eating behavior could be the worksite cafeteria, since it is a natural social context where most employees eat at least one meal during their workday. The Netherlands has a working population of more than 7 million people [
12] of which about 45% have lunch daily at the worksite cafeteria [
13]. Thereby, choosing the worksite cafeteria as a location to intervene in eating behavior gives the opportunity to reach people more than once as they visit the worksite cafeteria regularly. Finally, worksites could potentially reach a large part of the adult population including many who have not traditionally been engaged in health promotion activities [
14,
15].
Regarding the dietary intake of employees, improvements can be made. Although little is known about the current health status of Dutch worksite cafeterias, several studies show adverse effects of (associations with) foods produced and eaten outside the home. For instance, out-of-home eating has been associated with a higher energy and fat intake [
16,
17], a higher energy density [
18] and food portions in places to eat outside the home exceed standard portion sizes [
19]. Large portions in turn have been related to a higher energy intake [
20‐
23].
Today Dutch worksites cafeterias have already been used as a setting for interventions focusing on changing eating behavior [
24‐
29]. For example, the placing of informational sheets near food products with the caloric (kcal) value of a product translated into the number of minutes to perform a certain (occupational) activity [
24], or the labeling of low-fat products [
26]. Results of these interventions however were mixed. The environmental intervention of Engbers et al. [
24], was modestly effective in changing behavioral determinants towards eating less fat (social support, self-efficacy and attitude), but ineffective in positively changing actual fat, fruit and vegetable intake of office workers. Labeling low-fat products also showed partial effectiveness. For the whole study population no significant effects on consumption data were found. The data however did show a beneficial and significant treatment effect of the labeling program on total fat intake for respondents who believed they ate a high-fat diet. Sales data revealed a significant effect of the labeling program on desserts, but not for the other products [
26].
Also outside the Netherlands strategies to improve eating behavior in the worksite cafeteria are studied. For instance, increasing the availability of healthy foods like fruits and vegetables and products low in energy density [
30,
31], offering smaller portions [
32], providing nutrition information on menus [
33,
34] placing a sign with the message “Pick me! I am low calorie” on the low-fat milk [
35], or showing a nutrition logo on healthy products [
15].
However, not all strategies are effective in improving eating behavior [
29] and the quality and reporting of worksite intervention studies is low [
36], so searching for a new approach is needed.
A method introduced in this setting recently is the concept of nudging [
37]. Nudging is defined as changing the presentation of choice options in a way that it makes the desired choice – in our case the healthier option - the easy, automatic and default option, without forbidding any options [
38]. Nudges can be seen as relatively simple, easy to implement and inexpensive interventions. Besides, consumers preservation of liberty of choice is a key characteristic of nudging [
38]. Another strength of this relatively new strategy is the fact that it is effortless for consumers because it does not result in ego depletion [
39]. Ego depletion is the phenomenon that acts of self-control at Time 1 reduce performance on subsequent, seemingly unrelated self-control tasks at Time 2 [
40]. In this new field of nudging strategies, the focus is most often on the effect of one or two strategies within one intervention, for instance, Van Kleef et al., [
41] tested the nudge of offering healthy snacks in larger shares and at higher shelves at the checkout counter in a hospital staff restaurant. However, the character of nudges, not depleting self-control, make them suitable to use simultaneously. A combination of mostly proven effective nudging strategies would have potential to result in a cumulative effect, and has to our knowledge never been studied before, especially not in worksite cafeterias.
Next to nudging also relatively new in the field of intervention development for health promotion is social marketing. Social marketing seeks to develop and integrate marketing concepts with other approaches to influence behaviours that benefit individuals and communities for the greater social good [
42]. Furthermore, social marketing aims to change behaviour, by getting acquainted with the target audience. Social marketing is considered a useful tool in changing peoples’ health behaviour. Stead et al., [
43] found in their review that there was evidence that interventions adopting social marketing principles could be effective across a range of behaviours, with a range of target groups, in different settings, and can influence policy and professional practice as well as individuals [
43]. Carins et al., [
44] who also conducted a review, stated that social marketing when employed to its full extent offers the potential to improve healthy eating behavior [
44].
Some social marketing strategies can be seen as a form of nudging. They aim to change behavior and do not forbid undesirable behavior. Shaping the food environment by the use of nudging and social marketing techniques seems a promising strategy to examine in order to change purchasing and subsequently eating behavior. The worksite cafeteria is a suitable food environment to shape.
Considering this, the objective of this study is to develop an intervention, named: “the worksite cafeteria 2.0”, based on nudging and social marketing techniques to improve eating behavior of Dutch employees. Subsequently the aim is to describe the design of a study to measure the effect of multiple simultaneously executed strategies in “the worksite cafeteria 2.0” on purchasing behavior of visitors in Dutch worksite cafeterias. The research question of the described study protocol will be; What is the effect of a healthier worksite cafeteria based on nudging and social marketing techniques on the purchasing behavior of employees?