Diet and perception

This 2016 article explores the impact of the increasing exposure in society to images of desirable foods (what is often labelled 'food porn', or 'gastroporn') via digital interfaces might have, and whether it may inadvertently be exacerbating our desire for food (what we call 'visual hunger'). Here Spence et. al (2016) review the evidence for the potential profound effect viewing these images may have on neural activity, physiological and psychological responses and visual attention (especially in the ‘hungry’ brain). It is explained that the blame is often put on the global food companies for offering addictive foods, designed to use just the right amount of pleasurable ingredients such as sugar, salt, fat to hit the “bliss point” and for making these calorie-rich foods so accessible. The review aimed to find out if there are other implicit cues in our environments that might be triggering hunger more often than it is good for human well-being.

Sütterlin and Siegrist (2015) set up 4 experiments to find out whether people use simple heuristics to assess the healthiness of food products since for example the inclusion of the word “fruit” in “fruit sugar”, the colloquial name for fructose in Germany could mislead one to perceive the product as relatively healthy due to the association between fruit and health. Experiment 1 involved providing 164 individuals with one of two cereal bars, with one group given the nutrition table with the label “fruit sugar” and the other group provided with that labeled solely “sugar”. The results pointed to the participants holding a more positive perception of the “fruit sugar” cereal than the bars excluding the word “fruit”. Experiment 2 was a within-subjects designed version of Experiment 1, with all 202 subjects evaluating both cereal bars simultaneously, which resulted in the same trend occurring. Experiment 3 (N = 251) ruled out the alternative explanation that the effect could be due to differing inferences about the product's ingredients based on the label used, that is, that the product labeled with "fruit sugar" contains fruit. Results from the 4th experiment involving 162 participants indicated the labeling of the word “sugar” and its healthiness association mediated the previously observed effect. This study clarifies that symbolic information on food products can influence people’s perception of its healthiness, which can prove valuable from a marketing and public health standpoint.

Exploring different strategies on promoting the implementation of healthier diets, this study examined the perceptions and definitions of eating pleasures and healthy eating in a population from Quebec City, Canada. There were 12 focus groups formed, including men and women of normal weight and obese. The objective was to identify commonalities and differences between the participants’ perceptions and definitions and comparing the data based on sex and body mass index (BMI). The salient perceptions were similar among subgroups based on sex and BMI. In most cases eating pleasure was defined through food characteristics related to sensory qualities and psychosocial contexts whereas the definitions of healthy eating were mostly found to mention food characteristics related to nutritional quality and ways to regulate eating behavior. To conclude, the Quebecers’ concepts of eating pleasure and healthy eating were dissimilar but could be seen as compatible and suggests the use of eating pleasure could provide a promising way to promote healthy eating.

This review seeks to find the impact of cognitive features on the perceived healthiness of foods and the resulting influence on overall food choices and consumption. It is suggested the inclusion of nutritional information on products in the form of labels and claims, which was integrated as a strategy to promote healthy diet consumption, could be misinterpreted by the consumers. The findings of this review imply cognitive factors (including type of food and branding) may not consistently or systematically affect food choice and intake but significantly contributes to judgmental bias and can influence the person’s perception of healthiness.

A sample US subpopulation (281 adult parents) undertook this 2019 study investigating the influence of plate size on a person’s perceptions and recall of food and meal size. The parents drew and labeled the foods they expected to eat that night, drawing on either a 23cm or 28cm paper plate. There were apparent differences in food sizes drawn between the two plate sizes as well as between the sexes. Around 24% more food was drawn on the larger plates than the small plates. This trend was seen in both sexes, although men drew 37% larger food sizes on the 28cm plates than on the 23cm plates, and women had their portions 17% larger on the bigger plates. 60% of the overall differences in food size between plates was observed when the biggest food was drawn. Furthermore, bigger meat portions were drawn by both men and women on the 28cm plates. These results provide evidence of the influential role of plate size on these adults’ estimates of plate size, with the observed effect more substantial in men than women which could result in greater food consumption in men, especially meat products.

Harray et. al (2017) compared the perceived and actual intakes of energy-rich nutrient-poor ‘junk food’ (JF) and sugar-sweetened beverages (SSB) in young adults in Perth of Australia, by assessing before-and-after eating images of the standardised portions (143kcal) of JF and SSB. Amongst the adult participants (aged 18-30), mean consumption of JF+SSB was 3.7 (2.0) servings per day. The women who thought about drinking less SSB were found to consume more servings per day (1.5 (1.2)) than men who thought about drinking less (0.7 (0.5)). On the other hand, men who planned to cut down on JF ate more servings/day (4.6 (2.4)) than women who wanted to reduce JF intake (2.5 (0.7) servings). Those who consumed the least JF and SSB were individuals who paid a lot of attention to include healthy choices into their diet, who consumed significantly less than those who took only a bit of notice, were not thinking much about it and those who didn’t consider health at all in their food intake. These results suggest perceptions and attitudes regarding JF and SSB can be associated with level of consumption. Since those individuals who did not consider cutting down on these foods consumed larger amounts, they appear to be an important target group for promoting healthy eating.

This 2017 comparative study involving 570 people from Canada, China, Korea and New Zealand investigated the cultural influences on perception of food portions as a function of plate size. Previous research had suggested manipulations of plate size can directly affect perception of food intake but this present study claimed to be the first to examine differences in results between various countries and cultures. Photographs of ten culturally diverse dishes were presented on 27cm (large) and 23cm (small) plates before the participants rated estimated usual intake and expected fullness after the meal. After controlling for individual BMI, liking and familiarity of the presented food, the analysis revealed clear differences between cultures: in Chinese and Korean respondents plate size did not have an effect on expected fullness or estimated intake whereas the size manipulation significantly impacted upon Canadians and New Zealanders; participants from Canada and New Zealand also reported significantly higher estimated intake ratings than Chinese and Koreans, although estimated fullness ratings were found to be comparable or higher than from the Asian subjects. These results suggest from a cultural perspective that estimated fullness and consumption are learned through dining experiences and highlight the importance of considering eating environments and contexts when assessing individual behaviours relating to dietary consumption.

Since there is evidence indicating the potential approach oriented towards eating pleasure to promote the consumption of healthy foods, Vaillancourt et. al (2019) compared perceptions and the potential effect of pleasure-oriented as well as health-oriented messages on promoting healthy eating among French-Canadians. Perceived message orientation and effectiveness, perceptions towards healthy eating as well as emotions, attitude towards healthy eating, and intention to eat healthily were evaluated. The study population - consisting of 100 adults with an average age of 45.1, 50:50 male to female ratio - were randomly assigned to read one of the two leaflets with the messages, before completing questionnaires online and also reporting their experiences in a visit to the Institute of Nutrition and Functional Foods. Both pleasure and health messages significantly improved global attitude towards healthy eating while perceived message effectiveness and induced emotions in response to reading were similar between the two leaflets. The pleasure-oriented message was successful in inducing the perception that eating healthy can be pleasurable, with additional analyses also revealing the pleasure leaflet increased affective attitude towards healthy eating to a greater extent than the health leaflet. The health message appeared to improve cognitive attitude more than the pleasure leaflet however. The researchers conclude that the leaflets may be appropriate to promote healthy eating through health- and pleasure-related approaches.

Jezewska-Zychowicz and Guzek (2017) conducted a survey involving 344 consumers aged 20-65 years old to investigate whether dieting, perception of body weight, diet and preparing meals are linked to particular dietary patterns based on survey responses, and also to identify eating patterns based on declared food consumption rates (measured using a 7-point scale). Cluster analysis was used to identify three dietary patterns of behaviour: ‘potentially beneficial to health’, ‘potentially unfavourable for health; deficient’ and ‘potentially unfavourable for health; excessive’. Significantly more participants were of normal body weight, was dieting at that moment or had in the past, evaluated their diet as very good or good, prepared their meals at home and showed “potentially beneficial for health” behavior, all in comparison to other groups. Variations in responses to meal preparation were seen in the “unfavorable for health” dietary pattern, while less meals were prepared at home by those belonging to the “deficient” pattern. Finally, the writers claim that the pattern of potentially beneficial dietary habits correlated to weight control through a slimming diet and greater involvement in the meal preparation and that food choice skills need to be developed when educating people on nutrition.

In this qualitative study published in 2018 16 key informant interviews were conducted and eight focus group discussions took place in northern Ethiopia in order to find out people’s perception of a ‘healthy’ diet in this African country and the barriers to practice this idea of a ‘healthy’ diet. The Ethiopians’ practice was mostly consistent with their perception, while they sometimes acted contrary to the perception because of personal preference and physical or financial obstacles. People were often unconcerned by the health implications of their habitual dietary practice, such as drinking a lot of sweet coffee. This study investigated and has shown the dynamics between perception and practice of ‘healthy’ diets among people in northern Ethiopia with the aim of removing any obstacles to a beneficial diet and raising awareness in the country of non-communicable diseases (NCDs) such as cardiovascular disease and diabetes, which are increasing with regards to burden in these low-income countries.

Turnwald et. al (2019) tested whether taste-focused labels can attract higher vegetable intake compared with health-focused labels at five university dining halls across the United States. Across 137,842 diner decisions, 185 days, and 24 vegetable types, taste-focused labels increased vegetable selection by 29% and overall vegetable consumption as well compared with health-focused labels and by 14% compared with basic labels. In addition, taste-focused labels outperformed labels that merely contained positive words, fancy words, or lists of ingredients. As additional studies further inspected the mediators, moderators, and boundaries of these effects, it was discovered that increased expectation of a positive taste experience mediated the effect of taste-focused labels on vegetable selection, and moderation tests revealed greater effects in settings where tastier vegetable recipes are served. This research paper indicates that emphasising tasty and enjoyable attributes increases vegetable intake in real-world settings.

This 2015 study conducted focus groups with Brazilian university students to find out their perceptions of the concept of calories, how it relates to food healthiness, and the role of calorie information on menus in influencing food choices in different restaurant settings. Among the 21 undergraduate students who took part in this cohort, calories were understood to be energy units and their excessive intake was associated with weight/fat gain. However, food healthiness was not associated with calorie content, but rather with food composition as a whole. Calorie information on restaurant menus was not considered enough to influence food choice, with only some participants also using calorie information on menus to control food intake or body weight. The discussions between the students suggested their comprehension of healthy eating is a more complex issue than calorie counting, and they would need more information on nutrition, not only about calorie content, in order to influence food choices in restaurants.

Since food cues affect hunger and nutritional choices, the objective of the first study was to explore the impact of food cues on appetite-related hormones and to examine the functionality of the secreted hormones on macronutrient uptake in a healthy subpopulation. The healthy, non-obese participants were presented with random non-food pictures on the first day and then were shown food pictures on the second day. A second study was focused on confirming response differences of total and active ghrelin to stimulation with food pictures and to a meal followed by the stimulation. Duszka et. al (2020) also planned to identify factors contributing to response to food cues. In this second study the subjects were asked to drink a milkshake following the picture session and their levels of blood glucose, triglycerides and hunger-related hormones were taken. The concentration of several hormones measured in the blood were found to be interdependent, while in the case of ghrelin and gastric inhibitory peptide (GIP) as well as ghrelin and glucagon-like peptide-1 (GLP-1), this co-occurrence relies on the visual cues. Regulation of total ghrelin concentration following food stimulation is also highly individual and responders showed upregulated total ghrelin, while the concentration of active ghrelin decreased following a meal. Interestingly, there was a correlation identified between lower protein content and lesser colour intensity of food pictures with higher participants’ ratings of the pictures. After gathering all this data, it was concluded that observation of food pictures influences the levels of several appetite-related hormones, and the close link of visual cues to physiological responses may be of clinical relevance.

With the aim of improving the effectiveness of nutrition education programs and behavior change campaigns, Pettigrew, Talati and Pratt (2017) studied 409 Australian survey respondents aged 25-64 years on their perceptions of the meaning of four terms used to describe unhealthy foods: junk food, snack food, party food and discretionary food. The research found ‘junk food’ to be the term most aligned with unhealthiness, and likely to represent wording that is relevant to many target audience members. Other findings included the term “discretionary food” was not a familiar term for many respondents, and snack foods were considered to include both healthy and unhealthy food products. Both snack foods and party foods were often described as being consumed in small portions. These results highlighted that different terms for unhealthy foods can have substantially varying meanings for audience members and therefore, a detailed understanding of these meanings is required to ensure that nutrition guidance and health promotion campaigns use appropriate terminology.

The main objective of this 2012 Korean study was to determine whether self-perception of diet quality is connected to personality, impulsiveness, stress, coping strategy, sense of coherence, self-efficacy and social support. This cross-sectional study gathered data by conducting 15-minute face-to-face interviews with 1530 South Korean volunteers (aged 30-69) without a history of cancer. Respondents were more likely to perceive that they consumed a healthy diet if they were older than 50 years, lived with a partner, had a monthly family income greater than $4,000 USD, had a low perceived risk of cancer, consumed less alcohol, exercised regularly, had a less agreeable or conscientious personality, had low stress levels, had a high sense of coherence or self-efficacy, and had ample social support. These results associating psychosocial factors, such as personality, stress, sense of coherence, self-efficacy and social support with self-perception of diet quality can be used and analysed further to assist with the design of educational campaigns.

König & Renner (2019) conducted three studies with intervention strategies for boosting healthy food choice by prompting consumers to eat a colourful lunch at the appropriate moment. Effectivity and feasibility of this intervention strategy were tested in two laboratory experiments and one real-life, smartphone-based Ecological Momentary Intervention. The first study with 83 participants involved 4 meals (colourful, typical, healthy and low-calorie), the second with 42 subjects and tested 3 meals (colourful, typical and varied) from a Fake Food Buffet, and in study 3, 80 participants recorded images of 1,210 lunch meals over a period of 3 weeks using mobile visual food recording. All participants were asked to rate the prompts’ feasibility and in the second week, received a daily smartphone prompt to eat a colourful lunch. Results showed that prompting the sample to eat colourful foods increased the proportion of healthy foods consumed compared to typical meals in all three studies, with the individuals taking part in the study reporting that the prompt was easy to follow and act upon. In studies 1 and 2, colourful meals contained more fruit and vegetables, while in study 3 the prompt increased vegetable consumption. The colourful meals were said to be the tastiest in study one. This study suggests it may be promising to prompt people to eat colourful meals to encourage healthy food choices in daily life.