How does the food environment influence people engaged in weight management? A systematic review and thematic synthesis of the qualitative literature

Summary People engaged in weight loss or weight loss maintenance (weight management) often regain weight long term. Unsupportive food environments are one of the myriad challenges people face when working towards a healthier weight. This systematic review explores how the food environment influences people engaged in weight management and the policy implications. Nine electronic databases (CINAHL, Medline, PsycINFO, Academic Search Complete, Embase, Ovid Emcare, PubMed, Open Grey, and BASE) were searched systematically in May 2020 to synthesize the qualitative evidence. Eligible studies were conducted with adults (18+) in high‐income countries, available in English and published 2010–2020 with a substantial qualitative element and reference to food environments. Data were analyzed using a thematic synthesis approach. Quality assessment using the Critical Appraisal Skills Programme was undertaken. We identified 26 studies of 679 individuals reporting on weight management experiences with reference to the food environment. Limitations of the included studies included a lack of detail regarding socioeconomic status and ethnicity in many studies. The analysis revealed that food environments undermine efforts at weight management, consistently making purchasing and consumption of healthier food more difficult, particularly for those on a low income. For weight management to be more successful, concurrent actions to reshape food environments are necessary.

including digital apps, weight management groups, individual coaches, and clinical support. 7 With research demonstrating the limited longterm effectiveness of WMS, it is important to understand why individuals engaged in weight loss find it difficult to maintain their efforts.
People engaged in weight management often experience only short-term maintenance of weight loss due to the myriad challenges they face. 8,9 Research has shown that over 80% of individuals who lose the desired amount of weight initially experience weight regain after 1 year, 85% after 2 years, and over 95% after 3 years. 10 Individuals who experience weight regain often gain more weight than they lost during the dieting period. 11 Two qualitative systematic reviews conducted by Greaves et al. 12 and Spreckley et al. 13 have explored the experiences and challenges of successful long-term weight loss maintenance. Greaves et al. 12 discuss the psychological "tension" between the behavior changes needed for weight loss maintenance and existing habits. Management of this tension requires constant effort through self-regulation, renewing motivation and managing external influences such as temptations, social pressures and "high-risk" situations, for example, holidays or stress. Spreckley et al. 13 emphasize the importance of continuous monitoring and personalized, continuously evolving goal setting and the need to resist challenges.
The common theme in both reviews is that constant selfregulation and monitoring were key aspects of weight loss or weight loss maintenance (henceforth weight management), as well as managing external influences. Indeed, the self-regulation and monitoring were necessary to mitigate the challenges presented by these external influences, such as the "daunting" obesogenic food environment mentioned by Spreckley et al. 13 However, this extrinsic challenge to weight management is not explored in detail. This reflects the tendency for discussions about weight in research to focus on the individual's behavior change and characteristics, such as self-discipline or motivation, with less focus on how these characteristics are influenced and challenged by people's (food) environments as an important factor among wider drivers determining the condition of obesity. 9 The term "food environment" refers to the "settings with all the different types of food made available and accessible to people in their out-of-home environments as they go about their daily lives". 14 By influencing the food and drink options people have, food environments play an important role in shaping people's diets. 15 people buy food are the availability, accessibility and affordability of food, and media and advertising. 19 Food environments are a particular challenge for those on a low income for various reasons, which include the easy accessibility and high availability of inexpensive options high in fat, salt, and/or sugar (HFSS), particularly in low-income areas 20 ; the reduced accessibility of healthier supermarket options in some lowincome areas 21,22 and needing to go further to acquire low-cost food 23 ; and the cost of healthy food (perceived and actual). 24 Previous qualitative research has demonstrated the challenges people face when trying to achieve a healthier weight either individually or as part of WMS 12,25 and how the food environment influences food behaviors 19 ; however, the specific influence of a person's food environment on people engaged in weight management has not been explored in detail.
We undertook a systematic review of qualitative research to provide insights into (i) how people engaging in weight management

| Eligibility criteria and study selection
Articles were included if they were a primary study written in English and published between 2010 and 2020 inclusive. This time frame was chosen to ensure that participants' experiences were relevant to the present day. Studies also had to involve adults (18+) and substantial qualitative research methods, such as interviews or focus group discussions, to allow for in-depth analysis of participant experiences. Papers could be mixed methods or wholly qualitative: If mixed methods, there needed to be a substantial qualitative element that could have stood alone as a separate qualitative study.

Concept 2 Qualitative
Exclusion criteria Subject headings CINAHL "weight loss" OR "weight reduction programs" OR "Diet, reducing" Medline "weight loss" OR "weight reduction programs" OR "Diet, reducing" OR "obesity management" PsycInfo "weight loss" OR "weight reduction programs" OR "Diet, reducing" OR "obesity management" Academic search complete "weight loss" OR "dietary management" OR "reducing diets" Embase "body weight loss" OR "diet restriction" "weight loss program" OR "obesity management" OR "weight reduction" OR "body weight management" OR "body weight maintenance" Emcare "body weight loss" OR "diet restriction" Pubmed "obesity management" OR "weight loss" OR "weight reduction programs" OR "Diet, reducing" Subject headings CINAHL "qualitative studies" OR "semi-structured interview" OR "focus groups" OR "ethnological research" OR "ethnographic research" Medline "qualitative research" OR interview OR "focus groups" PsycInfo "qualitative research" OR interview OR "focus groups" OR "group discussion" Academic search complete "qualitative research" OR interviewing OR "focus groups" Embase "qualitative research" OR interview OR "ethnographic research" Emcare "qualitative research" OR interview OR "ethnographic research" Pubmed "qualitative research" OR interview as topic/methods OR "focus groups" The current review was explicitly interested in people's experience of losing weight or maintaining weight loss in their normal environment.
Studies that focused specifically on the experience of a weight management program, rather than on weight management itself, were excluded at either the title and abstract or full-text screening stage.
During the final paper selection, studies were excluded if there was little or no reference to the food environment due to the objectives of the study. This refinement was purposefully included later in the selection process, as it required detailed reading to determine references to the food environment that may not have used specific terminology.

| Screening process
Articles identified through database searches were imported into End-Note version X9. Duplicate and non-English language records were removed by KN. Two researchers (KN and AI) reviewed all titles and abstracts of the remaining articles independently using EPPI-Reviewer 4 to identify those suitable for full-text evaluation. Any discrepancies were discussed prior to full-text screening.
Inclusion or exclusion of full-text articles was conducted independently by KN and AI, who each read all articles. Final paper selection was finalized by second readings, and any discrepancies were discussed.
Two additional articles published after the search had been conducted and found independently were added. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram outlining the search and selection process can be seen in Figure 2.

| Quality assessment
The Critical Appraisal Skills Programme (CASP) tool for appraising qualitative research was used to assess the quality of studies included in this review. 27 No papers were excluded based on quality: The appraisal was used to understand the relative strengths and weaknesses of each paper and balance findings accordingly. researchers also allowed for elements that were not in this framework, hence the inclusion of social support as a descriptive code. Initial codes were accessibility, convenience, desirability, affordability, availability, marketing and regulation, vendor and product properties, and social support. The researchers did not code for the home food environment, as the analysis focused on the interaction between people and the outof-home food environment (e.g., in supermarkets, at work or when eating out in cafes and restaurants) and its influence on food consumption.

| Coding and data analysis
Two researchers (KN and AI) independently coded three papers using this framework and then cross-checked for quality assurance.
The remaining articles were subsequently coded in the same manner (50% by KN; 50% by AI). The third stage was the development of

Search term
1. Subject heading search "body weight loss" OR "diet restriction" "weight loss program" OR "obesity management" OR "weight reduction" OR "body weight management" OR "body weight maintenance" 2. Keyword searching (abstract) (obesity adj3 (program* or manag* or services)) OR (weight adj3 (los* or program* or reduc* or manag* or services)) OR dieting OR (diet* adj3 (program* or manag* or services))  included studies can be seen in Table 3. Only six studies included data related to socioeconomic status (SES), and many studies lacked data on the ethnicity of participants. Although two studies did not specify the number of each gender, there was a clear majority of female participants across the studies.

| Quality assessment
Of the 26 articles, only five met all criteria for aspects of quality within the CASP framework. However, the remaining studies predominantly lacked in the same two aspects: consideration of the relationship of the researcher to the participants and/or detail about the ethical considerations, which were likely omitted due to restrictive word limits. No papers were deemed poor quality.

| Key findings
Four major themes were identified to represent the influence of the food environment on people engaging in weight management: (i) Constant effort is required to navigate the food environment; (ii) people's efforts are consistently undermined by the availability and accessibility of less nutritious options in food environments; (iii) higher cost (real and perceived) of healthier produce creates challenges for those on lower incomes trying to lose weight; and (iv) when social situations intersect with the food environment, weight management is particularly challenging. An overview of themes and in which studies they were mentioned can be seen in This study included interviews with staff (facilitators) and attendees (service users) of a health improvement service; facilitator interviews have been excluded from this review. b Only data from participants in focus group 2-the group who had tried to lose weight and managed to sustain weight loss-were considered in this review.

| Constant effort is required to navigate the food environment
The most effective strategies for people engaging in weight management involve extensive planning around, or avoidance of, perceived unhealthy food-provision contexts Sustained weight management requires careful navigation of work and supermarket food environments. The most effective strategies employed in the included studies involved extensive planning around, or avoidance of, perceived unhealthy food-provision contexts and their temptations. Indeed, the importance of preparation and planning featured heavily. Challenging work food environments meant people had to employ the strategy of preparing food at home in order to avoid eating at irregular times at work, 39,41 often out of a vending machine. 43 To avoid eating HFSS options when out of home, people engaging in weight management had to allocate extra time for preparing and cooking healthy meals from scratch. 33,44,45,48,49,52 One strategy to cope in the work environment was not carrying money so that using the vending machines was not a possibility. 47 A variety of strategies were used to navigate supermarkets to avoid the purchasing or consumption of more than planned,

T A B L E 4 Overview of themes
Themes Subthemes References Theme 1: Constant effort is required to navigate the food environment.
The most effective strategies for people engaging in weight management involve extensive planning around, or avoidance of, perceived unhealthy food-provision contexts. Healthy foods can seem unattainable due to a higher cost (both real and perceived) than HFSS foods.   35,38 Fast food marketing and advertising was seen as pervasive and a real challenge to controlling weight, as it made less nutritious options very tempting. 30,53 Fast food options were also easier to access, as they were more likely than healthier options to be located close to homes and workplaces. 34 Healthier options are less easily accessible and less desirable The limited accessibility of healthier food options was identified as a difficulty for weight management. 40 Some people reported finding it more challenging to get to shops selling healthier foods, such as larger supermarkets, and doing so required further costs or effort for transport or delivery. 30,42 One study noted this was particularly the case in more deprived areas, where it was often necessary to take at least one bus to reach a supermarket and this necessitated taking a taxi home due to the weight of the shopping, which was an extra expense. 34 Furthermore, participants in one study commented that both walking and taking local transport (rather than driving) meant more exposure to all the options, hence more temptation. 53 Healthier foods were also seen as the least available ones at work. 49 In addition, healthier options in restaurants were considered to be less tasty or satisfying and thus were less desirable than other options. 43 People engaging in weight management saw eating out in cafes and restaurants as a time to enjoy food, which meant choosing options they knew would taste good and come in larger portion sizes. 43 Weight management is easier when there are healthy options available When healthier foods were easily available and easy to access, people engaging in weight management found it easier to follow a healthier diet. 38 Specific examples included access to healthier options on a university campus and the ability to bring in food prepared at home 48 and a weekly farmers' market at the workplace selling affordable boxes of fresh fruit and vegetables. 33

| Cost (real and perceived) of healthier produce creates challenges for those on lower incomes trying to lose weight
Healthy foods can seem unattainable due to a higher cost (both real and perceived) than HFSS foods A limited food budget was a significant challenge for some people engaging in weight management, with basic healthy foods seen as more expensive than less healthy options. 29,34,43 Participants in one study deemed it unaffordable to have healthy foods at home 43 and students in another study commented on the high costs of healthy food as an obstacle to buying it. 51 When discussing the challenge of affording healthy food, study participants drew comparisons with less healthy foods, which were much more affordable. 29,34 For instance, instead of steaks, cheaper burgers that could feed more people were considered a better option. 34 With healthy food costing more than less nutritious options, people engaging in weight management had to de-prioritize it when managing a low budget, in particular with families. 29,34 While food was a necessity, how much money was spent on food was flexible, which meant that "food is about the first thing that suffers." 29 Promotions encourage spontaneity and make less nutritious options even more tempting for those on low incomes When budgets are constrained, promotions have more appeal as they are perceived as a way to save money. 46 Planned shopping lists lost relevance when faced with offers, even if foods did not match the diet plan and for some, buying the cheapest or most reduced items was a point of principle. 46 People also reported a pleasure attached to looking for, and finding, bargains, which are most commonly for less nutritious foods and thus conflicted with trying to eat healthily. 46 This was particularly important for people who saw themselves as "food addicts" constantly tempted by food and thus more prone to be attracted by extraordinary prices. 35 Consequently, people on a low income had to choose between healthy eating goals and the "flexib[ility] to enjoy life in unreflected and spontaneous ways" 45 when faced with promotions for foods that did not match their goals.

| When social situations intersect with the food environment, weight management is particularly challenging
Social situations are difficult when trying to manage weight, as food is nearly always involved Socializing often means going out and eating or drinking with people, which is a challenge when following a weight management plan. 31,38,53 Participants across various studies saw social situations as one of the strongest challenges, as going out acted as a "trigger" for consuming HFSS food. 39,41,43,49 This was the case even outside of restaurants and cafes, as friends and colleagues were likely to bring less nutritious foods to social occasions. 53,54 How others expect someone to engage with the food environment can present a challenge to weight management strategies People's social networks often included people who ate the same way and disliked any change in one person's eating practices. 49 There was thus a social pressure to eat calorie-dense foods and drink alcohol to comply with social norms, 40,53,54 with some participants eating more at social events to make others feel good. 31,50 Women often experienced pressure from other women to eat more or have a treat, 44,50 and it was common to have a "saboteur" among friends who made negative comments about weight loss or healthier eating practices. 37 This was not restricted to women: In one study, men discussed how other men can be critical when eating in restaurants and trying to order more healthily. 42 People used specific strategies for social occasions, such as skipping desserts and appetizers or choosing healthier options when eating in restaurants. 52 At work and with friends, some accepted, but did not actually eat, the foods they were offered or only had a very small amount 50 ; others took their own food to social occasions. 44,52 This reflects the aforementioned avoidance of perceived unhealthy Misinformation online falls under a newer area of research coined "digital food environments," which "encompass the digital components that may be part of food environments and influence health and nutrition" 57 : Previous research has shown how people seeking health information online are exposed to a variety of dietary information and lifestyle advice, which often conflict with public health messages. [57][58][59] Efforts to manage weight were consistently undermined by the ubiquity and desirability of HFSS options, particularly in the workplace and areas where numbers of fast food outlets were high. 20 The importance of having healthier options more readily accessible and available in commercial areas and in workplaces has been documented previously 60,61 and was highlighted by participants in the reviewed studies.
Having healthier options nearby enabled people to follow a healthy diet plan more easily when unable to prepare food in advance.
As shown in previous research, healthy food was considered to be more expensive, and HFSS food was often discounted or cheaper to start with, making it more difficult for those on a low budget to maintain a healthy diet. 19,24 With many low-income areas more likely to have a greater number of HFSS commercial food options in the vicinity and often restricted supermarkets selling healthier food, [20][21][22] this review highlights how inequitable access to healthy food could act as a barrier to effective weight management.
A key aspect of the food environment that made weight management difficult was the social aspect of eating when meeting friends or with work colleagues. Social occasions centered around food and often involved eating foods or amounts that were not planned or desired in order to meet other people's expectations, as there was a certain stigma to eating differently to others. This reflects previous research demonstrating that food and eating relate not only to health but also to pleasure and social relations.

| Limitations and implications for further research
Although this review followed a rigorous methodology, there were some limitations to the included studies. One limitation was the general lack of specific data on SES and ethnicity in many studies, highlighting an important gap for future research. Clearer and attributable information on participants' demographic and socioeconomic situation would help put research findings into more specific contexts and has significant potential to strengthen the evidence base to inform future interventions. As the majority of studies included more women than men, more research into the male perspective of weight management would be beneficial to understand similarities and differences in experiences: One paper focused on masculinities and the experience of dieting noted a difference in how the men understood and practiced their dieting compared with the women in the study. 42 Additionally, research tends to be published about weight loss programs; the experiences of people dieting on their own are not well-

CONFLICT OF INTEREST
There are no conflicts of interest to declare.

AUTHOR CONTRIBUTIONS
Professor Corinna Hawkes' performed the conceptualization of the study and final review. Jessica Packer contributed advice and guidance in the initial review stages.