Integrating nutrition and physical activity promotion: A scoping review

Background This paper investigates actions that combine nutrition and physical activity which hold potential for ‘double duty action’ to tackle multiple forms of malnutrition simultaneously. Expanding on previous research on single component actions, we assessed the state of the literature to map integrated interventions across the life course to analyse potential double duty effects, and identify knowledge gaps and needs for future design, implementation, evaluation and research for effective double duty action. Methods A scoping review of peer-reviewed and grey literature was conducted to explore the pathways that extend from combined physical activity and nutrition promotion interventions, with potential synergistic effects on outcomes other than obesity. Electronic databases were searched for studies published between 1 January 2010 and 31 January 2020. Out of 359 articles retrieved, 31 peer-reviewed and 5 grey literature sources met inclusion criteria. Findings from 36 papers reporting on 34 interventions/initiatives were organised into 6 categories, based on implementation across multiple stages of the life course. Double-duty potential was assessed through a further stage of analysis. Findings This review has identified actions that hold potential for tackling not only obesity, but healthy diets, sedentary behaviour and quality of life more generally, as well as actions that explicitly tackle multiple forms of malnutrition. Importantly, it has identified crucial gaps in current methods and praxis that call for further practice-oriented research, in order to better understand and exploit the synergistic effects of integrated interventions on outcomes other than obesity. Conclusions Findings from across implementation settings suggest that even in situations where interventions are aimed at, or framed in terms of, obesity prevention and control, there are unexploited pathways for broader outcomes of relevance to nutrition and health and wellbeing more generally. Future design and evaluation of multisectoral approaches will benefit from an explicit framing of interventions as double-duty oriented.


Introduction
Malnutrition, in all its forms, is the largest single risk factor for the global burden of disease [1]. Every country is affected, and many countries are dealing with a "double burden" characterized by the coexistence of undernutrition with overweight, obesity or diet-related non-communicable diseases (NCDs) [2]. Alongside pervasive problems of undernutrition, the prevalence of overweight/obesity is rising dramatically, with 39% adults overweight or obese in 2016 [3]. Obesity is increasing in most countries, in both urban and rural settings, and across socio-economic levels-raising the risk of NCDs such as type 2 diabetes, hypertension, dyslipidemia, and various cancers [3]. 41 million of the world's 57 million deaths (71%) in 2016 were due to NCDs, with the highest burden falling on low and middle-income countries [4,5]. No country has yet succeeded in reversing this trend.
This paper responds to recent calls to review efforts to create enabling environments for 'double-duty actions' (DDAs) [6]. In their potential for preventing or reducing several forms of malnutrition simultaneously by targeting common or shared drivers of both undernutrition and overweight [6], double-duty actions hold great promise, especially in populations where multiple forms co-exist. The acknowledgement of involuntary exposure to underlying and structural determinants informs the wide range of strategies to promote wellbeing in multiple settings and across the lifespan. As a necessary step in developing an integrated agenda for addressing the root causes of malnutrition at all stages of the life course, this review focuses on integrated interventions/initiatives that combine both nutrition and physical activity, which have yet to be reviewed through a double-duty lens. This will expand on previous research on single component actions, with the anticipation that such integrated initiatives are likely to be framed mainly as obesity prevention and control programmes. Yet, being implemented primarily in countries with a high dual-burden or in specific settings (such as locations with poor socio-economic indicators and vulnerabilities) with higher risks of multiple forms of malnutrition and food insecurity, they have high potential for addressing all forms of malnutrition and related comorbidities.
Undernutrition and overweight/obesity are systemically connected to broader socio-political determinants of disease [7,8] and act synergistically (or 'syndemically') [9] where they cluster in poorer and more marginalised populations. Such synergistic effects are important. The UN's 2018 State of Food Security and Nutrition in the World report [10] employed a conceptual framework (page 30) that highlighted different pathways from inadequate food access to multiple forms of malnutrition. In addition to food and nutrition insecurity, the key nonnutritional pathway to overweight and obesity is mediated by poor mental health. This is based on growing evidence of associations between food insecurity and anxiety, stress and depression that are independent of other indicators of low socio-economic status in both resource-rich and resource-poor settings [11][12][13]. Stress brought on by food insecurity may cause non-homeostatic eating and may lead to the selection of 'comfort' foods, or highly palatable foods that are rich in fat, sugar, and sodium [14,15]. Finally, physical inactivity, in and of itself, is a major health issue [16][17][18][19][20][21][22]. Insufficient physical activity is one of the leading risk factors for death worldwide [23]. Globally, physical inactivity is estimated to account for between 6-10% of ischaemic heart disease, stroke, diabetes, and breast and colon cancer [24].
In this context, a key question is-are there benefits to integrating approaches to address both poor diet and physical inactivity simultaneously? Are there potential synergies to be exploited? Does integration of physical activity and nutrition promotion hold potential for generating effects on malnutrition that are more than simply additive, particularly in the context of these shared/syndemic broader determinants and contexts? Fig 1 is a modified form of the framework used in the State of Food Security and Nutrition in the World 2018 Report (page 30) [10] that highlights the pathways of interest that extend from combined physical activity and nutrition promotion interventions. Because many physical activity and nutrition promotion programmes include an element of school feeding (e.g. breakfast clubs), we also add this as an additional/optional intervention component. The diagram illustrates the pathways to two primary sets of outcomes (reduced obesity/overweight and increased dietary diversity/reduced micronutrient deficiencies), as well as one related set of intermediate outcomes (physical and mental wellbeing). While we do not hypothesise a link between physical activity and dietary diversity, the point of the diagram is to show that even in situations where interventions are aimed at, or framed in terms of, obesity prevention and control, there are unexploited pathways for broader outcomes of relevance to nutrition and health and wellbeing more generally. It is these 'additionalities', and their potential relevance for double duty action, that are the focus of this review.
In pursuit of these aims, we conducted a scoping review to a) map interventions across the life course to identify actions that combine nutrition and physical activity with potential double duty effects; b) identify whether outcomes of relevance are being appropriately measured; c) assess whether and to what extent these outcome measures can be used to inform DDA analysis; and d) identify knowledge gaps and needs for future design, implementation, evaluation and research for effective double duty action.

Literature search strategy
The search strategy was designed to capture both peer-reviewed and grey literature-the latter deemed essential, given that much knowledge and evidence on integrated nutrition and physical activity interventions derives from innovation in practice. For peer-reviewed literature, the databases PubMed and Web of Science, and studies from the Public Library of Science (PLoS) and The Lancet, were searched for relevant intervention studies. A targeted search based on search terms 'physical activity' AND 'nutrition' AND 'intervention' OR 'initiative' AND 'double burden' OR 'double duty' was carried out, with adapted variants for each database where appropriate. The syntax was built on Pubmed ["physical activity" OR exercise [MeSH] AND nutrition OR Diet, Food, and Nutrition [MeSH] OR dietary AND intervention OR initiative AND "double burden" OR "double duty"]. Syntax variations included search terms 'physical activity' (to include relevant Exercise [MeSH] terms for Pubmed) AND 'nutrition' (to include Diet, Food and Nutrition [MeSH] OR dietary OR nutrition (free text word) for Pubmed and TS = nutrition OR diet � for Web of Science) AND intervention � OR initiative � (wildcards) with applied filters for Timespan = 2010-2020 and Language (English). To be included in the review, studies must have a) addressed interventions or initiatives to promote physical activity and nutrition; b) been published from 1 January 2010 to 31 January 2020; c) provided a description of the intervention; and d) reported awareness, knowledge, behavioural, physiological, environmental or organisational change outcomes.
The following were excluded: a) studies that focused on synergistic elements without being integrated in interventions with a nutrition and physical activity component (e.g. single policy, taxation, changes to the built environment only); b) studies on actions that did not combine nutrition and physical activity but focused on either one of these elements individually; c) articles not associated with an intervention or community-wide initiative, such as studies on prevalence, correlates, or determinants, and d) articles in languages other than English.
For grey literature, conventional review methods for searching, appraising, managing, and synthesising the evidence base can be adapted [25][26][27][28]. A grey literature search plan was thus developed to incorporate five different searching strategies: a) grey literature databases, b) snowballing from available grey literature, c) customised Google search engines, d) targeted websites, and e) consultation with relevant experts. These complementary strategies were used to minimise the risk of omitting relevant sources. Since abstracts are often unavailable in grey literature documents, full-text screening was employed in the initial search and text was then coded into categories for future retrieval. Targeted searches were conducted to identify actions combining nutrition and physical activity. We included interventions and initiatives for which some degree of monitoring and evaluation was available. Structured searches of relevant websites and search engines were complemented by citation tracking and consultation with relevant experts, which helped to follow leads to additional relevant material.

Extraction and analysis
We used a standard extraction template to extract information on study and intervention characteristics. Data were collected on author(s), year of publication, study setting, study design and sampling, and purpose of study. Intervention-specific data were extracted on implementing organisation, type and description of intervention, outcomes, key findings and constraints to effectiveness (see Table 1). Appraisal of the quality of included studies, conducted separately following a standard assessment [29], additionally involved examination of the extent of participation, empowerment, multisectorality and sustainability of programmes. A narrative synthesis was undertaken in which insights were mapped with regard to delivery platforms that applied to different stages of the life cycle, in consideration of the recognised need to act beyond the first 1,000 days and across all life-stages to address root causes of malnutrition and prevent co-morbidities from escalating later in life [30,31]. (Continued ) Theory-based evaluation of advocacy, a novel approach to community youth obesity prevention. Data from adult leader surveys, decision-maker interviews, and baselinemidline-endline surveys with youth.

Lyn (2013)
Child care centre USA For-profit centres (n = 14) and non-profit centres (n = 10) were included in the program; 4 centres offered the Head Start program. The centres served a total of 2,042 children aged 2 to 5 years (range, 40-245 children per centre during the program).
The Child Nutrition and Women, Infants, and Children Reauthorization Act of 2004 included a provision requiring local education agencies participating in national nutrition programs (ie, National School Lunch Program, School Breakfast Program, and Special Milk Program) to adopt and implement local wellness policies in schools. The goal of the mandate was to promote wellness and health by focusing on nutrition education, physical activity, and other school-based activities to create healthy school environments. From February 2010 through April 2011, a program was conducted in southwest Georgia that focused on training caregivers in adoption and implementation of 6 wellness policies designed to improve nutrition and physical activity practices.
Significant improvements to total nutrition (P < .001) and physical activity scores (P < .001) were observed. Centres significantly improved the physical activity environments by enhancing active play (P = .02), the sedentary environment (P = .005), the portable environment (P = .002), staff behaviour (P = .004), and physical activity training and education (P < .001). Significant improvements were found for the nutrition environment (P < .001), and nutrition training and education (P < .001).
Wellness policy and training program in 24 child care centres in Georgia Environment and Policy Assessment and Observation instrument to identify changes to foods served, staff behaviours, and physical activity opportunities.
(Continued ) First report related to this project, describes the training and its dissemination between January and December 2015.

McIsaac (2017) School Canada
Population-based survey of students in grades 4-6 (about 9-12 years old) and their parents in the Tri-County Regional School Board (TCRSB) in Nova Scotia, Canada.
A Health Promoting Schools (HPS) approach aims to make schools a healthy place through a holistic approach that promotes a supportive 'school ethos' and emphasizes improvements in physical, social, and emotional well-being and educational outcomes.
Did not find significant differences between HPS and non-HPS schools. Results highlight the complexity of evaluating HPS in the real world. Differences in impacts measured. The findings suggest the potential role of a supportive school ethos for well-being in school.

Health-Promoting Schools program in Nova Scotia, Canada
Cross-sectional evaluation of a natural experiment.
(Continued ) (Continued ) Evidence of a wide range of innovative strategies to tackle obesity from state and municipal level. Evidence of increased opportunities for healthy nutrition and physical activity framed as expected potential benefits of enabling environment and decreased exposure to risk factors, rather than measured impacts on health outcomes.

State and Municipal Innovations in Obesity Policy
Review of local innovations in obesity policy (Continued ) Visual syntheses of results relevant to review objectives were produced for ease of access. Given that the wide array of study types and differential data quality do not allow for statistical synthesis of the results, the distribution of evidence was plotted as a simple bar graph to display relative magnitudes without implying functional relationships. Graphs were used to represent the distribution of studies across delivery platforms, outcome measures reported across programmes relevant to unexploited pathways specified in the conceptual framework, and characteristics of programmes that are relevant to the assessment of double duty action potential.

PLOS ONE
Due to the inclusion of outcome metrics of differing rigour and potential for bias across the included study designs, this approach to visual synthesis presents a number of advantages: a) it enables to visualise the characteristics of programmes which are most relevant to the stated objectives of the scoping review, despite the non-comparability of data across studies; and b) it permits an agnostic position with relation to the outcomes and metrics used in the studies, in line with the decision to scope the literature including diverse methodologies. The HIN commissioned TYF to help with the development of an Obesity Strategy for South London, moving away from a health service focused primarily on treatment of ill health, to one more focused on prevention with public and local communities taking more responsibility for their own health and wellbeing, and better managing their own conditions. Focus on adults whose weight is a problem for them in their lives, but not yet so severely obese that surgery is the best option. Two main groups: those needing motivational support to prevent them tipping over into becoming overweight, and those who need specialist weight management to prevent them tipping over into becoming morbidly overweight where health problems escalate rapidly. This outline of the contribution of the evidence served as a first step in assessing whether and to what extent the double-duty potential of actions through planned or potentially unexploited impact pathways could be assessed, at a time when the coexistence of multiple burdens of malnutrition is increasingly recognised as an urgent issue across countries. At the same time, the graphs make it clear that the current evidence base would not allow for a thorough systematic review and meta-analysis at this stage. This is particularly important for the identification of gaps which will need to be addressed if we are to make progress on double duty action to tackle malnutrition in all its forms.
Double-duty potential was assessed through a further stage of analysis. Evidence of awareness and/or applied knowledge of the links between interventions and multiple drivers of different forms of malnutrition was sought and recorded (S2 Table). We assessed whether interventions explicitly addressed different forms of vulnerability and inequality including those relating to age, gender, socio-economic or ethnic status and cultural identity. Reported outcomes in relation to underlying and structural determinants were also assessed with regard to their potential for creating an enabling environment for DDAs, importantly for both 'denovo' actions and 'retrofitting' of existing single-duty actions [6]. The level of detail and focus of the studies included in this review, however, did not allow for an assessment of whether interventions framed as obesity prevention or control are consistent with the 'do-no-harm' principle for double-duty action, whereby interventions addressing a single form of malnutrition ensure no harmful impact on other forms of malnutrition.

Results
The approach to study selection is shown in Fig 2. We identified a total of 675 records, including 620 from peer-reviewed database searches and 55 from grey literature searches. After removing duplicates (n = 206), a total of 359 peer-reviewed records were screened by title and abstract (55 grey literature articles, which did not provide an abstract, were screened in the following step). 98 articles, including 43 peer-reviewed and 55 grey literature articles were screened by full text. 31 peer-reviewed studies and 5 grey literature articles met our eligibility criteria.
In order to comprehensively assess the quality of studies and interventions, the WHO 'Good Practice Critical Appraisal Tool for Obesity Prevention Programmes, Projects, Initiatives and Interventions' [13] was adapted to the purposes of this review (S1 Table). A total of 36 studies satisfied quality assessment criteria and were included in this review.
Our results highlight a variety of different intervention types that meet inclusion criteria for this review. Reporting of the findings draws on information collected in the extraction matrix, detailed in the previous section. This is organised into six overlapping categories (Fig 3), which highlight entry points for implementation across the lifespan (the number of key studies that contributed to each category is specified in brackets): early care/preschool platforms (n = 7), school-based platforms (n = 14), out-of-school time (OST) platforms (n = 8), targeting of higher risk groups (n = 6), workplace platforms (n = 4), community-based initiatives (n = 24).

Early care/preschool platforms
Licensed child care centres and pre-kindergarten programmes provide an opportunity to reach large numbers of children, including those at risk of both undernutrition and overweight/obesity [32]. Factors considered in obesity prevention interventions include maternal health, nutritional and health literacy, family perceptions of healthy infant growth, family eating, cooking and exercise behaviour, and the role of obesogenic food environments [33,34]. Traditional initiatives provide education for staff, food service training, healthcare provider support, and target the attitudes of parents in relation to breastfeeding, milk banks, nutrition, and active lifestyle for their children. Some innovations include provider-child interactions around food and physical activity; emotion-based approaches aimed at parents' perceptions; learning of age-appropriate movements and use of simple inexpensive toys to support a life-

PLOS ONE
long habit of being physically active; opportunities for family-time in outdoor settings and active participation in community gardens [32][33][34][35][36][37][38]. Examples of innovation are evidencebased interventions which integrate new knowledge of developmental phenomena within the curriculum-e.g. the need for 8 to 12 exposures to a novel food before developing a preference for that food [37], or recommendations that preschool age children should have at least 60 minutes of unstructured (free-play) and at least 60 minutes of structured (adult-led) physical activity each day [37]. Although potentially effective in encouraging meaningful behavioural outcomes among caregivers and children, evaluations have often produced inconclusive results.
Several papers claim to have made some degree of progress in establishing the conditions for policy, systemic, and environmental changes. Examples of action include establishing multisectoral commitment to common agenda and priority-setting activities, asset mapping, provision of training and technical assistance, establishment of continuous communication networks and file sharing systems, shared quality rating methods, creation and alignment of resources that support childcare centres in family engagement strategies around breastfeeding, physical activity, and nutrition, drafting recommendations for improving existing programme wellness, nutrition and physical activity criteria, breastfeeding licensing and regulation standards for childcare programmes, and inclusion of nutrition and physical activity criteria in state quality rating improvement system [32,36,38]. However, specific outcomes are not measured or specified.
Evaluations of care centre-based initiatives often rely on self-reported data, and a few indicators that quantify the opportunities provided for improved healthy eating and physical activity [32,36,38]. Wellness policies and programmes focus on training caregivers in best practices for physical activity and nutrition that promote healthy weight for young children [38], healthy preschool time [32], development of a healthy environment conducive to healthy lifestyle choices [32], dietary behaviour at breakfast or over the course of one day [36], improving the physical activity environments for physical activity training and education and for active play, as well as the healthy weight environment by influencing the quality of foods served, caregivers' behaviour, and staff behaviour [32,36]. Often due to imperfect data collection systems, they fail to demonstrate whether additional opportunities produce behavioural changes and desired health outcomes.

School-based platforms
There is evidence that schools can shift dietary behaviour and physical activity practices over the course of an academic year [39,40]. Many school-based health promotion interventions have traditionally focused on changing individual behaviour, rather than targeting broader social or environmental determinants that influence behaviour. The promotion of health-conducive environments in schools is the focus of new interventions which provide opportunities for engaging in healthy nutrition and physical activity throughout the day [34,[40][41][42][43]. Innovations include attention to breakfast habits, food service in canteens and availability of snacks and drinks in vending machines, bans on drinks except milk and water, healthy snacking breaks, provision of free fresh fruit in the classroom, and engagement with food retailers in the school's surroundings [36,37,[43][44][45][46]. Physical fitness and motor skills tests, awareness building and questionnaires on dietary habits are administered for monitoring uptake of healthy behaviours [47]. Some initiatives reinforce the communication of health-related messages by employing age-appropriate educational materials informed by dietary guidelines, online learning, and messaging [34,48]. Limitations have been found in the use of generic materials provided for educational purposes that do not consider local contexts, e.g. availability and seasonality of fruit and vegetables, or tweaking of locally-relevant culinary styles and methods [37].
Multicomponent interventions in schools that combine educational, curricular, and environmental elements are thought to be more effective than interventions targeting single components or behaviours [39]. High-intensity interventions that focus on multiple aspects, interventions with periods of time greater than six months in duration, sustained funding, and parental involvement in the content and/or planned actions, are frequent recommendations for achieving effectiveness of programmes [36, 43-45, 47, 49]. Holistic approaches that promote a supportive 'school ethos' and emphasize improvements in physical, social, and emotional well-being and educational outcomes refer to the children's health-related quality of life (HRQoL) measured using the Health Utilities Index (HUI) [44]. Others measure students' quality of life in school with the Quality of Life in School (QoLS) instrument [39]. This is a measure of general well-being and satisfaction based on positive and negative experiences of school activities which target diet quality (defined by adequacy, variety, balance and moderation), physical activity, screen time, and self-efficacy. The findings suggest the potential role of a supportive school ethos for well-being in school. But further, longer term and longitudinal research is needed to demonstrate the potential effects of such approaches on student health, well-being, and academic achievement into the future [39,44].

Out-of-school time (OST) platforms
Some interventions focus on out-of-school time (OST) programmes as key environments for targeting school-aged children and adolescents. Dissemination of guiding principles for healthy snacks, beverages, and physical activity in large and complex OST organisations has been observed to be most successful when implementation strategies are customised, aligned and integrated with existing goals and routine practices [48,50]. Competing demands for time in the curriculum have been found to be a barrier to participation [50,51].
One major difference between school-based and afterschool initiatives appears to be a shift from a view of beneficiaries as passive recipients of interventions to one of active participants. A novel approach in programmes that combine nutrition and physical activity, is the engagement of young people in advocacy activities. Initiatives focused on youth engagement in public-private partnerships, record impacts on policy and industry behaviour [41,52]. The use of 'star power' of professional sport organisations with celebrity status in collaboration with youth groups has shown positive outcomes at the individual, group and community levels [45,50]. By getting directly involved, young people become more aware of their own behaviour and take steps to get healthier. Additionally, they exert influence on other young people as well as their families. Interventions that impact on health and wellbeing of adolescents (e.g. through increased opportunities for healthy eating, and increased uptake of moderate to vigorous physical activity (MVPA) components) offer second chances to the most disadvantaged [43,50,51,53]. Investments in adolescent health and wellbeing bring benefits not only in their future adult life, but also for the next generation of children as future parents.
Components which focus on the promotion of health and wellbeing of children and adolescents include the integration of evidence-based, practical, and accessible guiding principles for promoting drinking water instead of sugar-sweetened beverages, boosting movement and physical activity in all programmes, and fuelling up on fruits and vegetables [52]. There is evidence of increased moderate or vigorous physical activity, replacement of flavoured milk with non-fat or regular milk, modest improvements in mean numbers of healthy food items served per day, increase in awareness of healthy labelling through promotional materials and healthy food labels but no significant increase in purchase of fruit and vegetables or other healthy items [43], increase in caregivers' nutrition-related efficacy beliefs, increased knowledge on healthy diets and physical activity in children and caregivers [51]. Whilst a definition or exact measure of wellbeing is not specified in these studies, the development of actionable guiding principles for healthy eating and physical activity in OST platforms is often combined with an existing portfolio of national initiatives that blends science and business strengths to prevent childhood obesity, with general health and wellbeing as broad outcomes [41,43,45,50,52,53].

Targeting higher risk groups
Some interventions intentionally target school districts with a high percentage (at least 50%) of students eligible for free or reduced-price meals (FRPM), from urban, suburban and rural regions, for increased likelihood of impact [49]. Others focus on schools with a high percentage of students from families considered to be at higher risk of obesity in some settings, e.g. from migrant minorities [47,51]. In addition, multidisciplinary, family-centred outpatient interventions based on social cognitive theory have been implemented to prevent further increases in BMI and improve quality of life (QoL) in children and adolescents with obesity in healthcare-based settings and through home-visits [46]. Though recent data suggest that these can have a positive effect on childhood obesity, with impacts on anthropometric and laboratory value outcomes, it is still unclear which program components are most beneficial and how they affect QoL, or whether home visits contribute to stigma [34,39,46]. The evidence shows mixed results. Some initiatives to promote healthy weights in children from vulnerable populations report no changes in measurements of health-related quality of life in children (HRQoL), based on previous month recall questionnaires measured at baseline, endline, and six-month follow-up, and no differences in health-related quality of life within sites covered by these initiatives [51]. One study found that following a 1-year intervention, the participants' BMI z-scores and QoL improved, while other adiposity-related measures of body composition remained unchanged [46]. These studies stress the need to generate more data on healthrelated QoL outcomes [46,51].

Workplace platforms
In recent decades, employers have increasingly established workplace-based health promotion programmes to reduce rising health-care costs, attract and retain talent, improve employees' quality of life and minimise absenteeism [54,55]. The intermediate aim is to help employees adopt healthier lifestyles and lower their risk of developing costly chronic diseases, while improving worker productivity. Some initiatives have focused on health promoting workplaces (HPWPs) as ideal settings for influencing the physical, mental, economic and social wellbeing of workers (and in turn their families, communities and societies), creating large multisectoral networks that engage in training of trainers, toolkit development for employers and workers and promotion of healthier food and physical activity environments, as well as decreased exposure to other risk factors for non-communicable diseases and injuries (NCDIs) [56].
Programmes typically entail an assessment of employee health, personalised feedback on how employees can improve their health, and the provision of resources and programming designed to promote wellness [55]. The stress is on creating an enabling environment for health promotion, addressing sedentary behaviours as a leading cause of NCDs in non-labourintensive industries, promoting awareness and potentially fuelling public demand for healthconscious policies in other domains of adult life, as well as those aimed at prevention during childhood and adolescence. Scores of employees' perceptions of employer support for health and lifestyle risk is derived from self-reported physical activity, nutrition, and other risk factors, such as tobacco use [55,57]. Science-and practice-based prevention and wellness strategies are being implemented in different countries, with the expectation that these will lead to specific, measurable health outcomes to reduce chronic disease rates [54][55][56][57]. However, these programmes employ wellbeing as a broad guiding principle rather than as a specific impact measure. [Percentages in Fig 4 represent outcomes for which specific measures were used.]

Community-based initiatives
Complementary to initiatives aimed at high-risk segments of the population are interventions that aim to change policies, systems, and environments, including priority-setting at the community and population levels. This reflects an awareness that end-stage treatment of chronic disease is not sufficient, and that there is a need to promote healthy lifestyles across the lifespan, and to address risk factors in multiple settings [58], including more deep seated health inequities based on high levels of income inequality. Notable examples are large scale development interventions aimed at broad societal change, such as the 'Prospera/ESIAN' Programme in Mexico [59] or the 'Zero Hunger/Academia Saúde Program' in Brazil [60,61]. Both are based on a systems-thinking approach. EsIAN, is a national strategy to strengthen the health and nutrition component of the previously implemented Prospera conditional cash transfer programme. This addresses undernutrition and obesity, with a focus on the first 1,000 days of life [59]. The Zero Hunger Program combines comprehensive multisectoral efforts that incorporate obesity in health, nutrition, food, and national security policies, including the promotion of physical activity in the community, the regulation of food industry advertising and marketing practices to young children, and social action and community empowerment through mass communication and capacity development of local nongovernment organisations [61].
Beyond large scale policy-led initiatives, there is contrasting evidence as to the reach, implementation, adoption, effectiveness and sustainability of programmes which tackle the obesogenic environment [39,54,[62][63][64]. Existing evidence on the extent to which social and community-based approaches incentivise exercise and awareness is inconclusive [34,62]. A major issue in assessing impact remains the quantity, quality and consistency of data collection and monitoring. Nevertheless, there is evidence of positive change in awareness and behaviour that are likely to be conducive to positive outcomes in the prevention of multiple forms of malnutrition [41,49,65]. Interventions that encompass the multiple contexts that influence people's choices (i.e. family, school, work, community, culture and society) and related policy arenas, are believed to be crucial for the prevention of comorbidities in children, adolescents, and adults [48,66]. Analysis of post-intervention data shows a broad range of impacts at micro-, meso-and macro-level, without allowing for a conclusive assessment of intervention components in absolute terms, stressing how the extent to which change is influenced by single or combined components is highly contextual.
Some initiatives use traditional intervention platforms but combine them into multicomponent, community-family-school-based childhood obesity interventions [51,52,67]. Intervention components include attendance of individual nutrition and physical activity counselling sessions for children and parents, healthy cooking workshops, and school-based extracurricular sessions of nutrition education. Measurements from similar programmes of indicators such as waist circumference, BMI-for-age, intake of fruit and vegetables, fibre consumption, sugary soft drinks intake, physical activity levels and screen time, suggest that multicomponent interventions are a promising strategy, at municipality level, to tackle childhood overweight and obesity [32,39,46,52]. These studies record improved dietary quality in terms of dietary intake and eating patterns, diet adequacy, variety, balance and moderation, lower total energy, protein, carbohydrate, sugar and total fat consumption, decreased contribution of sugary beverages to total daily energy intake, replacement of sugar-sweetened beverages with more nutritious fluids, higher intake of milk products, higher intake of dietary fibre, and increased consumption of fruit and vegetables, with changes being sustained at six months from intervention [32,39,46,52]. Some programmes also highlight major barriers to uptake and effectiveness. Importantly, initial resistance to the programme by families with overweight children, results in low attendance [34]. Some of the strengths are the standardised intervention protocol for consistent delivery across settings, and the establishment and promotion of a partnership between health centres and local governments. However, despite positive outcomes in the short term, the lack of longer-term followup makes these results less robust for drawing conclusions on sustained change within targeted communities [51,52].
More effective, higher-intensity strategies are more likely to be found in communities with the longest duration of investment [34,43,56,62]. Strong (high-dose) community-based obesity prevention strategies have been shown to lead to improved health behaviours, with increased opportunities for healthy eating and physical activity, and measured impacts on moderate to vigorous physical activity, dietary diversity, increased awareness achieved through educational materials and food labelling, decreased intake of sugar-sweetened beverages, and increased intake of fruits and vegetables [43,49]. One programme, aimed primarily at children from vulnerable populations (i.e., rural, remote, northern, aboriginal and multicultural communities across Canada) which employed similar strategies, however, was found to have limited effectiveness [51], with healthier cooking and eating choices and play-based physical activity being reported during implementation of the programme, but with no long-term effectiveness. Importantly, motivation has been found to be stronger when beneficiaries are involved, supported and encouraged [43,49,53]. Comprehensive evaluations that systematically highlight areas of success and challenges are not available for most programmes, which present self-reported changes in awareness and behaviour but no objective measurement of their extent, making it difficult to compare interventions [38,51].
There is positive evidence of programmes focused on components such as social marketing, stakeholder engagement, network and partnership development, community-directed needs assessment and capacity building, showing changes in community capacity, but no or few impacts on individual knowledge, beliefs, perceptions and behaviour with relation to healthy eating, physical activity and sedentary lifestyle habits [34,51,54,58,62]. In contrast, some programmes-depending on their specific characteristics, including the number and duration of mutually reinforcing activities-show improvements in awareness, knowledge and behaviour indicators, but no measurable impacts at the community level, beyond the potential establishment of environmental conditions conducive to healthy behaviour [38,51]. Studies which compare implementation, uptake and impact of the same initiatives or programmes across communities [54,62] have generated divergent results with regard to a number of indicators. Projects are as diverse as the local problems they address (including substance abuse, diabetes, access to fresh foods, access to primary health care and mental health care, problems with the built environment, and equity issues within communities) [62]. These findings show that effectiveness of intervention strategies is dependent on individual and community factors.

Discussion
In this review, we sought to synthesise and summarise major initiatives that have integrated physical activity and nutrition promotion, with potential synergistic effects on multiple forms of malnutrition, in order to distil some key lessons for informing the future investigation, design and implementation of nutrition-relevant actions. We find that 33 of the 36 studies meeting inclusion criteria are limited to focusing or reporting on obesity outcomes. Also notable is the fact that 22 of the 34 programmes that satisfied quality assessment were implemented in one country (USA), with 3 others from Canada, and 1 each from an additional 8 countries, and just one multi-country initiative.
Only two interventions (reported by 3 of 36 studies) were explicitly targeted at both obesity/ overweight and other forms of malnutrition. These are complex, large scale, multisectoral programmes in countries (Mexico and Brazil) with a high burden of both undernutrition and overweight/obesity, and related comorbidities. Their implementation of a wide range of components involves concerted action across many sectors and policy levels, with the specific objective to address multiple forms of malnutrition. Some of the components encapsulate years, in some cases decades, of social protection policy, while others are more recent additions.
The remaining programmes included in the review were considered to have potential for 'double duty' based on several considerations. Consistently with the Cochrane PROGRESS--Plus framework [7], we applied an equity lens to the classification of studies, based on their recorded awareness of/focus on characteristics that stratify health opportunities and outcomes (Fig 5). Demographic and socioeconomic factors associated with malnutrition were taken as important markers of potential for interventions to perform double duty (S1 Text). These elements encompass multiple vulnerabilities influenced by underlying and structural determinants of malnutrition, as well as recognised environmental exposures to risk throughout the lifecycle. The attention given to vulnerabilities and inequalities in the studies examined were deemed important for all forms of malnutrition. A stress on environmental aspects was therefore considered as having potential for reducing the differential effects of the PROGRESS-Plus factors, importantly for both 'retrofitting' and 'de-novo' actions, by targeting multiple drivers and facilitating broader changes that are conducive to double duty. Additional attention was paid to consistency with the 'do-no-harm' principle. While this extra layer of analysis was precluded by a lack of sufficient information in reviewed studies, it will be crucial for strengthening the knowledge base for future action.
As illustrated in Fig 5 (and explained in detail in S1 Text on the rationale adopted), those studies demonstrating an awareness of/focus on known links between demographic and socioeconomic factors, differences in endowments of individuals and groups, associated circumstances and behaviours adopted by individuals and households to cope with limitations in given settings, and consequent inequalities in health outcomes and life expectancy within and across communities, were considered to have potential for double duty.
Most health promotion interventions have traditionally focused on changing individual behaviour as an immediate determinant of ill health, rather than targeting broader socio-political or environmental determinants that influence behaviour [35,39,41]. Healthy nutrition and physical activity participation however are acknowledged to be dependent on factors beyond an individual's control, with programming and intervention efforts necessary across the lifespan, in multiple settings, and under various life circumstances [68]. To affect mass change, those involved in programming and delivering nutrition and physical activity interventions must address not only individual lifestyle behaviours that contribute to malnutrition and related comorbidities, but also the underlying and structural causes of health inequalities, perceptions of body and health, and stigma [69]. This shift in emphasis has created opportunities and challenges for those involved in nutrition and physical activity programme delivery. Instead of end-stage treatment of chronic disease in healthcare settings, the new focus on prevention across the lifespan entails a shift in resources towards promotion of healthy lifestyles, and early recognition and treatment of risk factors and symptoms in multiple settings [70], which is implicit in much of the literature.
Such broader considerations mean that multi-component and longer-term interventions are needed to ensure sustainability beyond the initial outcomes that may be measured by some of the shorter term, single component interventions. There may be a trade-off between the intensity of the intervention that can be delivered and resources needed to sustain intensive, multi-component, multisectoral programmes over time. But time-limited, intense interventions are not sufficient if a return to one's normal environment means a return to the range of individual and structural factors which might shape behaviour [64]. There are also potential savings from disinvesting in interventions which are unlikely to achieve long term or systemic results. The evidence reviewed also suggests effective targeting needs to be taken into account in intervention design and implementation as well as informed decisions about the different needs and proclivities of different population groups. Nutrition interventions targeting mothers, infants and children, are known to have considerable benefits for the prevention of all forms of malnutrition. But this does not imply that we ignore the needs of other affected populations. Studies here report multiple benefits of targeting affected populations later in the lifecourse, including targeting of adolescents [45,50,53]; or targeting adults in the workplace for prevention and control of comorbidities later in life [55][56][57]. High risk groups can also be specifically targeted via referral services or community and home outreach [34,39,46,49,51].
Across the studies we also see the importance of understanding the wider context of implementation highlighted repeatedly. Programmes require tailoring to the social, economic, cultural, and demographic features of a region, with attention paid to identification of the best strategies in relation to age, gender, socioeconomic status, cultural identities and spheres of influence of the participants [51,53,58,62]. Engagement with local stakeholders and placebased planning of strategies is key to sustained change [43,54], ensuring relevance to people's day to day lives, and the identification of community-specific barriers to uptake and adherence. Studies often highlight the importance of strengthening the capacity of people and networks already active in the community and building on existing initiatives, instead of adding new ones [34,62,63].
In highlighting these findings, we acknowledge a number of limitations of this review and across the studies examined. Although we include an additional assessment of study quality, the findings reported above are drawn from a range of studies of variable quality, including from grey literature sources. We did not exclude such findings as we think they warrant further discussion and evaluation as part of future interventions and more rigorous research and evaluation design. More broadly, while studies reviewed report on impacts at micro-, meso-, and macro-level, their findings vary. Some report varying degrees of impact on individual awareness, knowledge and behaviour, but no impact at community level [46,47], whilst others report impacts on underlying and structural determinants at environmental level, but no measured impact on individual awareness, knowledge and behaviour [38,51,54,65]. There were some studies which show measured impacts in setting-specific outcomes but study participants reverting back to usual behaviour in other settings in which they conduct their everyday lives [34,65]. Others show effects in the short term (during the implementation window) but no measured effect on longer term outcomes [39,49,51]. There were also some studies which demonstrated impacts on programme outcomes without affecting (or possibly exacerbating) health inequalities [42].

Conclusions
This review has addressed an important knowledge gap in the growing field of double duty research. By mapping major interventions and initiatives that combine nutrition and physical activity components, it has identified actions that hold potential for tackling not only obesity, but healthy diets, sedentary behaviour and quality of life more generally, as well as actions that explicitly tackle multiple forms of malnutrition. Importantly, it has identified crucial gaps in current methods and praxis that call for further practice-oriented research, in order to exploit the synergistic effects of integrated interventions on outcomes other than obesity. Future design and evaluation of multisectoral approaches will benefit from an explicit framing of interventions as double-duty oriented. At the very least, single issue interventions should attempt to specify whether and how they ensure that no harm is caused to other forms of malnutrition and wellbeing. Implementers and evaluators alike would benefit from a clearer framework of how this is to be achieved, in order to satisfy the requirements for effective double duty action set out by the World Health Organization [6] and, more broadly, for the achievement of the Sustainable Development Goals (SDGs). This needs to be facilitated by those pushing for double duty action, so that evidence for independent evaluation can be made available through more conscious and comprehensive design.
Supporting information S1 Table.