Health Education Research Advance Access originally published online on April 10, 2006
Health Education Research 2006 21(4):527-537; doi:10.1093/her/cyl003
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The ‘balance intervention’ for promoting caloric compensatory behaviours in response to overeating: a formative evaluation
1 Department of Public Health, Erasmus MC, Rotterdam 3000 DR, the Netherlands
2 Department of Health Education and Health Promotion, University of Maastricht, the Netherlands
3 Netherlands Nutrition Centre Foundation, The Hague, 2508 CK, the Netherlands
*Correspondence to: B. Wammes. E-mail: b.wammes{at}erasmusmc.nl
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Abstract |
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To help people prevent weight gain, the Netherlands Nutrition Centre initiated the ‘balance intervention’, which promotes moderation of food intake and/or increased physical activity in response to occasions of overeating. The aim of this study was to determine whether intervention materials were appreciated, encouraged information seeking and increased motivation and caloric compensatory behaviours. A three-group randomized trial with pre-intervention measures (n = 963, response 86%) and post-intervention measures (n = 857) using electronic questionnaires was conducted among participants aged 25–40 years, recruited from an Internet research panel. The first group received a printed brochure and electronic newsletters (print group), the second group was exposed to radio advertisements (radio group) and the third group was the control group. Multiple regression analyses were used to investigate the impact of the materials on self-reported prevalence of overeating, attitudes, perceived behavioural control, intentions and compensatory behaviours. At follow-up, we found significantly more positive attitudes, intentions and dietary action in the print and radio groups. However, participants who received the radio advertisement had a significantly lower perceived behavioural control. No effects were found on the prevalence of overeating. The results indicate that the intervention materials have potential for increasing people's attitudes, motivation and self-reported behaviour actions, with a possible negative side-effect on perceived behavioural control.
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Introduction |
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Because weight gain is an important risk factor for overweight and obesity later in life [1, 2], prevention of weight gain may be the key to arresting the obesity epidemic [3]. The risk of gaining weight and developing obesity varies over the life cycle and is most likely to occur in young adults because of important events that often occur in that life phase. Starting one's career, getting married and having children can all affect behaviours that influence energy balance [4–8]. There is strong evidence that trends in adult weight gain are induced by environments with a high availability of palatable, energy-dense foods and sedentary living [3, 9–11]. These ‘obesogenic’ environments increase the risk of overeating [12, 13]. Overeating refers to consuming more energy than is expended. Short-term overeating is a common habit in many societies. It is associated with parties and celebrations and forms a risk for weight gain and, eventually, for becoming overweight or obese if overeating happens frequently over longer periods of time and is not compensated [13, 14].
To help people prevent weight gain in such an environment, the Netherlands Nutrition Centre initiated what is known as ‘balance intervention’, which aims to promote quick ‘caloric compensation’—i.e. moderating food intake and/or increasing physical activity in response to occasions of overeating—in order to maintain a neutral energy balance. The ‘balance’ approach accepts that occasions of overeating are likely to occur and focuses on making people aware of these occasions of overeating, and to motivate and enable them to compensate for them within a short span of time. The intervention is specifically targeted at adults aged 20–40 years, and there are plans to use radio advertisements and printed materials as the communication channels.
The present study was a formative evaluation of the balance intervention materials that the Netherlands Nutrition Centre planned to use in a nationwide campaign to promote compensatory behaviours. Since internal valid evaluation of combinations of mass media communications are almost impossible to conduct, especially when such communications are distributed nationwide, it is important to test such intervention materials before a nationwide launch. The aim of the present study was to test the application, appreciation and immediate effects in order to enable further improvement of the balance intervention [15–17]. The primary aim of this study was therefore to evaluate the media components of the balance intervention among young adults aged 20–40 years in a randomized experimental design by assessing whether the materials were (i) appreciated and encouraged people to seek further information and (ii) resulted in more positive attitudes, perceived behavioural control, motivations towards compensatory behaviours and self-reported actions related to caloric compensation.
We hypothesized that the radio advertisement was suitable for making people aware of the concept of compensatory behaviours and for motivating people to seek further information on how to apply these behaviours; the print materials were intended to enable people to start using more compensatory behaviours, since they included more practical information on practical skills.
In addition, we looked at possible side-effects based on the number of self-reported periods of overeating, especially in those known as ‘restrained eaters’, who may be more susceptible to overeating prompted by thoughts, emotions and situational cues [18, 19]. Restrained eaters may perceive the balance intervention as such a situational cue. It is therefore possible that the intervention may be used as ‘permission’ for overeating, especially in restrained eaters.
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Methods |
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Recruitment and procedures
Study enrolment took place in July and August 2004. Participants were recruited from a random sample (n = 1119) of an Internet research panel. To be eligible for the study, participants had to be (i) aged 20–40 years, (ii) not currently pregnant, (iii) willing to receive a brochure in the post at their home address and be able to listen to recordings of radio advertising on their home computer and (iv) not planning to be on holiday during the 4-week intervention and data-collection period.
A three-group randomized trial with pre- and post-intervention measures was conducted. Data were collected using web-based electronic self-administered questionnaires. Following the baseline assessment that was completed by 963 respondents (86.1% response rate), participants were randomly allocated to a control group (n = 309) or to one of two intervention groups (print group, n = 330; radio group, n = 324). Follow-up data were collected after a 4-week intervention period and included questions about the main outcome measures listed below.
A total of 857 participants completed all phases of the study. Analyses were conducted on 286 subjects in the print group (86.7% response rate), 289 subjects in the radio group (89.2% response rate) and 282 subjects in the control group (91.3% response rate).
The intervention materials
The Netherlands Nutrition Centre developed the printed materials and radio advertisements. The intervention materials were designed for Dutch adults aged 20–40 years and were based on information gathered by four focus-group interviews and a feasibility study among participants aged 25–35 years. The focus-group interviews were conducted to gain insight into awareness of overeating, the frequency of overeating and engagement in compensatory behaviours. Additionally, a group session was organized to examine the feasibility of caloric compensation in response to overeating among 27 volunteers who were recruited through advertisements. Participants attended a 1.5-hour group training session conducted by dieticians from the Netherlands Nutrition Centre, addressing awareness of occasions of overeating, and possibilities for caloric compensation with caloric restriction or increased physical activity; participants were asked to try this out for 1 month. At a follow-up meeting (4 weeks after the training), participants gave feedback about their experiences and difficulties related to caloric compensation. Responses from the group were used to develop and revise the print materials and radio advertisements. Drafts of the intervention printed materials were further pre-tested among 20 volunteers.
Print intervention
Participants who were randomly allocated to the print group received a printed brochure (in calendar format) at the start of the 4-week intervention period, an electronic newsletter in the second and fourth weeks, and one set of low-calorie recipes in the third week of the intervention period.
The brochure and the newsletters contained general information related to prevention of weight gain, and practical information to increase awareness about overeating and skills related to caloric compensatory behaviours. The brochure was entitled ‘The Balance Day’ with the subtitle ‘Don’t get fat!’ (see Fig. 1). First, some information was given about the gradual process of weight gain and the importance of taking steps to prevent this. The balance day was introduced as a strategy to prevent any further weight gain. Subsequently, information was given in order to explain the concept—in other words, information on how to apply the balance day approach. In addition, several practical recommendations were given on when and how to introduce a balance day approach: ‘Exercise is the way to expend energy and keep a healthy body weight. Exercise at least five days a week for half an hour. Also, activities at home such as vacuum cleaning and gardening are examples of exercise’. In addition, some examples were included for increasing awareness of when overeating might take place, such as during dinner parties, celebrations, when having drinks and during holidays. To help people choose low-calorie foods on their balance day, four tables were included with information about the caloric content of several foods typically eaten at breakfast, lunch, dinner and between meals, in which low-calorie foods were highlighted.
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The brochure explicitly mentioned that people should not misuse caloric compensation as an excuse to overeat more frequently, but that caloric compensation is meant to help them deal with often virtually unavoidable occasions when too many calories are eaten. Finally, participants in the print group received a set of recipes by email for low-calorie, low-fat, high-vegetable main courses, desserts and snacks suitable for caloric compensation.
Radio intervention
Two radio advertisements were developed to encourage people to seek information about caloric compensation. Both advertisements were recordings of a dialogue between two people illustrating an example of compensatory behaviours in response to overeating. During the 4-week intervention period, each week the radio intervention group received both radio advertisements by way of an electronic file (as an attachment to an email message). They were asked to open the file on their computer and listen to the advertisement. These emails gave additional information on how to contact the Nutrition Centre if they wanted further information on caloric compensatory measures.
Measurement
A self-developed questionnaire was used for the pre- and post-test measurements. The questionnaire was tested for reliability by analysing test–retest reliability in 47 respondents [who were in the same age group and body mass index (BMI) range as the participants] who were asked to complete the questionnaire twice within a 10-day period. The internal consistency of the scales was established in the sample of the present study with Cronbach's alphas. The participants completed questions on socio-demographics, use and appreciation of the materials, and attitudes, perceived behaviour control and actions related to caloric compensation.
Socio-demographic characteristics
Information on age, gender, educational level and self-reported height and weight was gathered during the recruitment procedure. The baseline questionnaire included additional questions about the respondent's native country and about that of their parents. Respondents were defined as being of Dutch origin if both their parents were born in the Netherlands, and otherwise were considered to be of non-Dutch origin. The information on height and weight was used to calculate BMI [BMI = weight (kg)/height (m2)]. Participants were categorized as being overweight (BMI 
25) or not overweight (BMI < 25).
Use and appreciation of the intervention materials
The post-test questionnaire differed in length between the intervention groups, because specific questions on attractiveness, appreciation and usability of the intervention materials were added. Respondents were asked whether they had received the intervention materials and whether they had used them (i.e. whether they had read the brochure, newsletter and recipes and whether they had listened to the radio advertisements). In addition, to evaluate the materials, questions were asked on how good, interesting and personally relevant they were (answers were on a five-point scale).
Attitudes, perceived behavioural control and motivations
The post-test questionnaire contained questions on the two possible compensatory strategies available, in other words, eating fewer calories (caloric restriction) or expending more calories by being physically active. Both categories of behaviours were measured with four items, referring to four potential periods when overeating can be compensated: (i) the day before, (ii) on the same day, (iii) the day after and (iv) within a few days of overeating. The questionnaire assessed attitudes, perceived behavioural control and motivations with respect to these eight strategies for compensatory behaviours. Scales for attitudes (e.g. ‘Do you think it is good or bad to compensate in this way?’) and perceived behavioural control (e.g. ‘Do you think it is difficult or easy to compensate in this way?’) consisted of four items each, which were answered on a five-point scale (‘very bad’ to ‘very good’; ‘very difficult’ to ‘very easy’). The intention was measured with two single items asking whether the participants intended to compensate overeating with caloric restriction and whether they intended to compensate overeating with extra physical activity; answers were given on a five-point scale (‘definitely not’ to ‘definitely yes’). The Cronbach's alphas (0.63–0.91) and the test–retest correlations (0.53–0.91) of the psychosocial measures were moderate to high, with the exception of the test–retest correlation for ‘caloric restriction attitudes’ (0.35) and ‘increased physical activity attitudes’ (0.21).
Compensatory behaviours
The post-test questionnaire continued with questions on how often participants were engaged in dietary or physical activity compensatory behaviours at the four designated periods for compensation over the last month. These questions were answered on a five-point scale: (i) almost never, (ii) less than once per week, (iii) onece or twice per week, (iv) three or four times per week and (v) five times per week or more. A mean score was calculated for the items related to the four occasions of compensation with caloric restriction (Cronbach's alpha = 0.75; test–retest reliability = 0.65) and increased physical activity (Cronbach's alpha = 0.87; test–retest reliability = 0.66) with higher scores indicating that individuals reported higher frequencies of dietary or physical activity compensatory behaviours.
Prevalence of overeating
At pre- and post-test, people were asked to report the frequency of overeating in the last month on a five-point scale: (i) almost never, (ii) less than once per week, (iii) once or twice per week, (iv) three to four times per week and (v) five times per week or more. At follow-up, we additionally included a 12-item self-report measure to assess the frequency of overeating in situations that could be labelled as ‘high-risk’ situations for overeating and weight control efforts, such as during the weekends, at birthday celebrations and other parties (see Table III), again on a five-point scale. A mean score for these 12 items was calculated (Cronbach's alpha = 0.87; test–retest reliability = 0.70), with higher scores indicating that individuals experienced higher frequencies of overeating in the previous month.
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Restrained eating behaviour
At pre-test, the Dutch Eating Behaviour Questionnaire (DEBQ) [20] was included to measure restrained eating tendency. The restrained eating scale contains 10 items and focuses on usage of strategies for limiting food and energy intake (e.g. ‘When you have put on weight, do you eat less than you usually do?’ ‘Do you try to eat less at mealtimes than you would like to eat?’). All items have a five-point response format: (i) never, (ii) seldom, (iii) sometimes, (iv) often and (v) very often. Participants were classified as highly restrained eaters if their score on the restraint scale was above the mean, as proposed by the norms of the DEBQ [20].
Analyses
Chi-square tests and analyses of variance were performed to test for baseline differences between study groups. Descriptive statistics were used to describe the frequencies of engagement in different possible compensatory behaviours; no tests were done to avoid multiple testing. The impact of the intervention on psychosocial factors and self-reported behaviours was tested with multiple linear and binary logistic regression analyses, with group and baseline scores as independent variables. Interaction terms were included to investigate whether the respective intervention effects were different for restrained eaters, women, overweight persons, people living with children and participants with lower levels of education compared with non-restrained eaters, men, participants with a healthy body weight, people with no children and more highly educated respondents. In case of significant interactions, stratified analyses were conducted. Due to the number of statistical analyses, P < 0.01 was used to indicate significant differences.
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Results |
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Socio-demographic characteristics of the participants
Mean age was 27 years (SD = 5.3); the mean BMI was 24.3 kg m–2 (SD = 4.5) with 33.6% of the participants having a BMI > 25 kg m–2; 51.8% of the participants was female; 68.1% of the respondents had a higher educational level (university degree or higher professional training); 91.2% of the participants were of Dutch origin; 19.4% had children living at home and 68.2% of the participants were classified as restrained eaters. No baseline differences were found in these variables between the three study groups.
Use and appreciation of intervention materials
Table I shows that almost all the participants in the print group reported they read the brochure and newsletters. Compared with the newsletter and recipes, the brochure was most appreciated. About 40% of the participants in the print group were encouraged to visit the Internet site of the Nutrition Centre to seek further information. The recipes in the print group and the radio advertisements in the radio group were less appreciated. Few participants reported they had used the recipes. Furthermore, the results show that the radio advertisement did not encourage participants to seek further information (Table II).
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Intervention effects on psychosocial factors
Table III shows that at post-test, the participants in both the print and radio groups had significantly more positive attitudes and intentions towards compensation compared with the control group. However, the participants in the radio group had significantly lower scores on perceived behavioural control related to dietary compensation compared with the control group. No differences were found between the study groups with regard to intentions for physical activity compensatory behaviours.
Prevalence of overeating
Table III shows that there were no differences in post-test scores on overeating between the print and radio groups. Additionally, we found no significant interaction between restraint eating and the radio group (ß = –0.03, P = 0.51) and the brochure group (ß = 0.01, P = 0.58).
Table IV shows that, overall, 38.3% of the respondents experienced overeating at least once a week during the 4-week intervention period. Respondents reported that these occasions of overeating were most common during the weekend, when watching television (TV) or when not feeling well.
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Compensatory behaviours
Table III shows that participants in the print and radio groups had significantly higher post-test scores on caloric restriction compensatory behaviours compared with the control group. No differences were found between study groups on physical activity compensatory behaviours.
On average, participants reported that they engaged in compensatory behaviours less than once a week over the 4-week intervention period (Table III). The results on the composed measures were reflected in the prevalence of the individual compensatory behaviours (Table V). Respondents reported they most often engaged in caloric restriction or physical activity compensatory behaviours the day after overeating: 21.4% and 17.5%, respectively, reported doing this for weight-control purposes at least once a week.
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Interactions
No significant interaction effects of the study group with age, education level, household size, weight status or restraint eating were found for any of the effect indicators.
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Discussion |
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About 40% of the respondents in the present study experienced occasions of overeating at least once a week. The present study further indicates that the balance intervention materials were associated with more positive attitudes, intentions and self-reported compensatory caloric restriction in response to overeating. However, no effects on reported physical activity compensation were found, and a majority of respondents reported using compensatory behaviours less than once a week. There were no indications that the intervention resulted in undesirable side-effects, such as more self-reported occasions of overeating. That effects were stronger for dietary compensation probably reflects the fact that the intervention materials were more diet oriented. This formative evaluation of intervention materials to be used in a nationwide campaign explored the appreciation, use and immediate impacts on self-reported psychosocial variables related to compensatory behaviours in response to overeating and potential determinants of such behaviour. This study was a first step in the phased process of establishing applicable and evidence-based weight-gain prevention interventions [15, 17].
Since internal valid evaluations of mass media interventions are difficult (if not impossible) to conduct, especially when such interventions are launched nationwide, it is important to test the potential effects of the individual components of mass media campaigns in randomized trials before the campaign is launched [16, 21, 22].
Several limitations of the study need to be addressed. First, this study was restricted to effects on self-reported behaviour and cognitions and was not designed to investigate effects on body weight. In the present study, we could not investigate the physiological evidence that the compensatory behaviours advocated indeed led to a neutral energy balance. Second, we could only explore short-term effects and have no information about whether the reported behavioural changes were maintained. Third, the self-reports used may be influenced by social desirability bias [23]. No measurement of the tendency to give socially desirable answers was included in the present study, so adjustment for this issue was not possible. However, since the present study is a randomized controlled trial, the tendency to give socially desirable answers should be equally distributed over the three groups. Fourth, although the psychometrics of the self-reported measures was mostly acceptable, we found low test–retest correlation for some of the scales used. Such low correlations may be the result of actual change, or may also reflect low reliability of the measure. Finally, in terms of generalizability of the results it should be noted that the participants in the current study were recruited from an Internet panel. Although this resulted in high response rates, our sample included a higher proportion of more highly educated people and an under-representation of people from ethnic minorities in Dutch society [24]. However, we found no differential intervention effects according to level of education or ethnic background. Furthermore, the present study tested the intervention materials in a setting that promoted exposure to the materials in a way that might not be possible to realize in nationwide implementation.
Several studies that made use of experimental or quasi-experimental designs to evaluate behavioural interventions offered some insights into effective mass media strategies. Such studies revealed that well-developed educational interventions using radio and TV broadcasts supplemented with print materials have contributed significantly to public awareness and may help to increase knowledge, influence attitudes, ‘beliefs’ and motivations. Evidence for behaviour change, however, appeared to be less strong, and only few of these studies reported effects on potential proximal behavioural determinants such as intention and self-efficacy [25–29]. We found an intervention impact on intentions as well as attitudes towards engaging in compensatory behaviour. The media messages may have resulted in greater awareness of the possibility of using compensation to try to prevent weight gain—in other words; the media messages may have introduced new beliefs that led to attitude change. For respondents who were already familiar with the compensation approach, the messages may have made these beliefs more important.
Because attitudes and motivations are important precursors for behaviour change [30], we can conclude that the increase in attitude and intentions in the present study can contribute to better compensatory behaviours related to caloric restriction. However, we found lower levels of perceived behavioural control after the radio advertisement intervention. Various behavioural change theories, such as the theory of planned behaviour [31], social cognitive theory [32] and the health belief model [33] indicate the importance of perceived control or self-efficacy in affecting behaviour. Perceived control or self-efficacy have also been found to predict behaviour in a variety of health domains, including weight loss, diet [34–36] and physical activity [37–39]. The present study suggests that both the brochure and the radio intervention led to stronger engagement in compensatory behaviour, but that the radio intervention also resulted in lower perceived control. These results confirm the findings of previous research on mass media, which show that mass media messages like TV and radio commercials are less appropriate for inducing behaviour change because they do not provide practical information in order to improve people's perceived behavioural control [16]. Since the radio advertisement did not provide information to strengthen perceived control, the experience with compensatory behaviours in the radio group may have led to more realistic but lower perceived behavioural control, since compensation behaviours are complex and may be difficult to apply. Combining the radio advertisement with the brochure may help to strengthen perceived control and seems to be essential, since mass media alone is not appropriate for inducing behaviour change. If the materials are implemented on a larger scale, both materials will indeed be combined. The radio commercial will be used especially to motivate people to get the brochure and read it. Nonetheless, the negative impact of the radio advertisement on behavioural control should discourage the Netherlands Nutrition Centre from using the radio advertisement in its present form in the nationwide campaign, because these advertisements failed to encourage participants to seek further information.
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Conclusion |
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The present study suggests that the balance intervention materials motivated study participants to seek caloric compensation after occasions of overeating. For the radio advertisement, a possible negative side-effect on perceived behavioural control was found. Further research is needed to establish whether promoting compensatory behaviours can indeed help people to keep a neutral energy balance.
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Acknowledgements |
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This research was supported by a grant from the Netherlands Nutrition Centre Foundation.
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References |
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Received on June 10, 2005; accepted on February 4, 2006
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