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International Journal of Behavioral Nutrition and Physical Activity

Springer Science and Business Media LLC

Preprints posted in the last 90 days, ranked by how well they match International Journal of Behavioral Nutrition and Physical Activity's content profile, based on 15 papers previously published here. The average preprint has a 0.03% match score for this journal, so anything above that is already an above-average fit.

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Children's and Parents' Perspectives on Universal Free School Meals in Wales: A Mixed Methods Study on Health, Wellbeing and Barriers to Uptake

Locke, A.; James, M.; Brophy, S.

2026-03-04 health policy 10.64898/2026.03.02.26347394 medRxiv
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BackgroundUniversal Free School Meals (UFSM) were introduced by the Welsh Government in 2022 to provide every primary school child (aged 4-11) with a free meal at lunch time by 2024, aiming to improve nutrition and reduce inequality. While evidence suggests UFSM can support dietary quality and social inclusion; uptake remains inconsistent, and concerns have been raised regarding meal quality and portion sizes. Aims/ObjectivesThis study explored the perceptions of children and parents regarding the rollout of UFSM in Wales, focusing on perceived health, wellbeing and social impacts whilst also identifying factors influencing non-uptake. MethodsA mixed-methods study was conducted, combining qualitative focus groups with 56 children in year 6 (aged 10-11) across eight primary schools in Wales. A cross-sectional survey was also completed by 410 parents from 110 Welsh primary schools. Qualitative data from focus groups and open-ended survey questions were analysed thematically using Braun and Clarkes framework, whilst closed-ended survey items were analysed descriptively to complement and contextualise qualitative findings. ResultsThree themes emerged from the childrens data. (1) The Food Experience, (2) The Social Value of Lunchtime, and (3) Fuel for Learning and Feeling Good. Children valued the social and emotional aspects of mealtimes but reported mixed experiences with food quality, variety, and portion sizes. Parents similarly expressed concerns about meal nutritional quality but also highlighted the policys benefits in reducing financial strain, stress, and daily time pressures. ConclusionsUFSM is widely supported for promoting inclusion and access to food. Nevertheless, improving meal quality, portion sizes, and menu diversity is essential to sustain participation and maximise the policys long-term health and equity benefits.

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Future health gain from increasing physical activity in Australia, including multiple physiological effects of physical activity, and falls and injury risk: A simulation study

Bourke, E. J.; Wilson, T.; Maddison, R.; Blakely, T.

2026-03-30 public and global health 10.64898/2026.03.28.26349629 medRxiv
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Abstract Background: Previous physical activity simulation studies only account for the effects of cardiovascular diseases, diabetes, dementia, and some cancers, which neglects many of its costs and benefits. We estimate the health and economic impacts of increased physical activity in Australia, including those on mental health, increased injury rate, and conditions mediated by other risk factors, commencing 2021, over 20 years. Methods: We used a Proportional Multistate Lifetable Model specified with disease rate and risk factor forecasts, and causal associations, derived from the Global Burden of Disease study and other sources. Findings: If all Australians shifted to the maximum physical activity level of 4200+ MET-min/week, there would be: 653,000 (230,000 - 1,210,000) or 0.16% more HALYs lived; 9,720 (7,400 to 12,700) or 1.33% fewer deaths before age 75; increased working age income of AUD$16.8 billion ($12.8 - $22.2 billion); and decreased health expenditure of $748 million (-$4.46 billion - $6.98 billion) or 0.02%. Net health gains diminish for each additional 600 MET-min/week increase in physical activity, and above 4,200 MET-min/week the health costs from injuries outweigh the reduction in health costs from avoided disease. Because of injuries, increasing physical activity in the lowest activity group to meet the physical activity guidelines reduces health expenditure more ($1.86 billion; 896 million - 3.13 billion) than shifting to maximum activity levels. Interpretation: Increasing physical activity levels in Australia would improve population health (even allowing for injuries due to participation), reduce health spending, and increase income. Funding: Australian Sports Commission. TB is funded by NHMRC Investigator Grant (2023) #2026992

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UPDATE trial Stage 2: a pre-post exploratory analysis of a behavioural support intervention to reduce ultra-processed food intake, increase minimally processed food intake, and increase physical activity in adults living with overweight or obesity

Buck, C.; Dicken, S. J.; Heuchan, G. N.; Conway, R. E.; Brown, A. C.; Jassil, F. C.; Blair, E.; Ranson, C.; Ruwona, T.; Makaronidis, J.; van Tulleken, C.; Gandini Wheeler-Kingshott, C. A. M.; Batterham, R. L.; Fisher, A.

2026-04-03 nutrition 10.64898/2026.04.01.26349973 medRxiv
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Introduction High consumption of ultra-processed foods (UPF) is associated with adverse health outcomes and weight gain. Despite increasing calls for behavioural strategies to reduce UPF intake, no theory-informed intervention targeting UPF reduction has been evaluated in UK adults in alignment with national dietary guidance. We assessed the feasibility, acceptability, and preliminary behavioural and clinical outcomes of a multi-component intervention designed to reduce UPF consumption (and increase physical activity (PA)/minimally processed food (MPF) intake). Methods In this exploratory single-arm pre-post study, adults (N=45) living with overweight or obesity and habitual UPF intake [&ge;]50% of total energy were offered a 6-month behavioural intervention following a controlled feeding phase (UPDATE trial, stage 1). The intervention was developed using the Behaviour Change Wheel and Capability, Opportunity, Motivation-Behaviour (COM-B) model and included one-to-one sessions with a behavioural scientist, tailored print and digital materials, peer-support meetings, and a moderated group chat. Feasibility outcomes included uptake, retention, and intervention fidelity. Secondary outcomes included COM-B constructs, dietary intake, PA, clinical and self-reported outcomes, and qualitative feedback. Results Uptake was 91% (41/45). Retention at 6 months was 68% (28/41), with 83% (34/41) providing follow-up data (intention-to-treat). Median attendance at one-to-one sessions was 86% (interquartile range (IQR): 57-100) with 56% (23/41) attending all sessions (per-protocol). Fidelity to core behaviour change techniques was high. At 6 months, COM-B scores improved for healthy eating (+7%, standard deviation (SD): 8; p<0.001) and physical activity (+5%, SD: 9; p=0.013). UPF intake decreased by 25% of total energy (95% confidence interval (95%CI): -32, -17), with a corresponding increase in minimally processed foods (+23%; 95%CI: 17, 29). Vigorous physical activity increased (+60 min/week, IQR: 0-180), weekday sitting time decreased (-61 min/day, SD: 110), and weight reduced by 3.8 kg (IQR: -8.5-1.0; p=0.001). Findings were similar in per-protocol analyses. Qualitative data indicated perceived improvements in wellbeing and habit formation. Conclusion This theory-informed intervention demonstrated good feasibility and acceptability and was associated with improvements in targeted behavioural mechanisms and health-related outcomes. A randomised controlled pilot trial is warranted to evaluate effectiveness and refine implementation.

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Tailoring physical activity recommendations to reduce cardiovascular mortality: interactions with age, sex and body morphology

Schwendinger, F.; Infanger, D.; Rowlands, A.; Schmidt-Trucksäss, A.

2026-03-27 epidemiology 10.64898/2026.03.25.26349341 medRxiv
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Background: This prospective cohort analysis investigated how age, sex, and body morphology modify associations of physical activity (PA) intensity, duration, and volume with cardiovascular disease (CVD) mortality. Methods: We analysed wrist-worn accelerometer data from 8,661 adults (51.9% women) in the National Health and Nutrition Examination Survey. The outcome was CVD mortality. PA intensity and volume were quantified using the intensity gradient and average acceleration, respectively. Survey-weighted Cox proportional hazards models were used to estimate associations, including interaction terms with age, sex, or body morphology (waist-to-height ratio as indicator of adiposity). Results: Median (interquartile range) follow-up was 81 (69, 94) months. All hazard ratios (HR) compare 50th with 25th percentile. Beneficial associations between CVD mortality and PA were stronger in younger than older adults for intensity (e.g., 45-year-olds: HR=0.47, 95%CI:0.29-0.75 vs 75-year-olds: HR=0.75, 95%CI:0.54-1.06), and volume (e.g., HR=0.18, 95%CI:0.07-0.71 vs 0.29, 95%CI:0.16-0.51). In women, intensity-related association were stronger than in men (HR=0.45, 95%CI:0.31-0.65 vs HR=0.79, 95%CI:0.50-1.24). Volume-related associations were stronger in men (HR=0.37, 95%CI:0.22-0.60 vs HR=0.24, 95%CI:0.11-0.51), though with earlier plateauing and greater uncertainty. Associations were observed across waist-to-height ratio levels but attenuated at higher values (intensity: waist-to-height ratio 0.5, HR=0.45, 95%CI:0.29-0.69 vs 0.6, HR=0.69, 95%CI:0.49-0.97; volume: 0.5, HR=0.07, 95%CI:0.03-0.17 vs 0.6, HR=0.28, 95%CI:0.17-0.45). Conclusion: Older adults and men may benefit more from increasing PA volume than intensity, whereas younger adults and women may benefit more from higher-intensity PA. Although benefits were observed across adiposity levels, associations were attenuated as adiposity increased, suggesting stronger benefits in individuals with low-to-moderate adiposity.

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The effect of sedentary behaviour and physical activity on 1719 diseases: a Mendelian randomisation phenome-wide association study (MR-PheWAS)

Xu, J.; Parker, R. M. A.; Bowman, K.; Clayton, G. L.; Lawlor, D. A.

2026-04-14 public and global health 10.64898/2026.04.10.26350507 medRxiv
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Background Higher levels of sedentary behaviour, such as leisure screen time (LST), and lower levels of physical activity are associated with diseases across multiple body systems which contribute to a large global health burden. Whether these associations are causal is unclear. The primary aim of this study is to investigate the causal effects of higher LST (given greater power) and, secondarily, lower moderate-to-vigorous intensity physical activity (MVPA), on a wide range of diseases in a hypothesis-free approach. Methods A two-sample Mendelian randomisation phenome-wide association study was conducted for the main analyses. Genetic single nucleotide polymorphisms (SNPs) were first selected as exposure genetic instruments for LST (hours of television watched per day; 117 SNPs) and MVPA (higher vs. lower; 18 SNPs) based on the genome-wide significant threshold (p < 5*10-8) from the largest relevant genome-wide association study (GWAS). For disease outcomes, we used summary results from FinnGen GWAS, including 1,719 diseases defined by hospital discharge International Classification of Diseases (ICD) codes in 453,733 European participants. For the main analyses, we used the inverse-variance weighting method with a Bonferroni corrected p-value of p [&le;] 3.47*10-4. Sensitivity analyses included Steiger filtering, MR-Egger and weighted median analyses, and data from UK Biobank were used to explore replication. Findings Genetically predicted higher LST was associated with increased risk of 87 (5.1% of the 1,719) diseases. Most of these diseases were in musculoskeletal and connective tissue (n=37), genitourinary (n=12) and respiratory (n=8) systems. Genetic liability to lower MVPA was associated with six diseases: three in musculoskeletal and connective tissue and genitourinary systems (with greater risk of these diseases also identified with higher LST), and three in respiratory and genitourinary systems. Sensitivity analyses largely supported the main analyses. Results replicated in UK Biobank, where data available. Conclusions Higher levels of sedentary behaviour, and lower levels of physical activity, causally increase the risk of diseases across multiple body systems, making them promising targets for reducing multimorbidity.

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Interactive Physical Activity Apps: Do the ABACUS and the MARS Measure Up? A Descriptive Analysis of Behaviour Change Taxonomies

Ori, E. M.; Baay, C.; Ester, M.; Toohey, A. M.

2026-02-22 public and global health 10.64898/2026.02.18.26346599 medRxiv
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The ubiquitous use of digital tools may be beneficial for improving physical activity across diverse populations. It remains unknown however, how publicly available, cost-free physical activity apps adhere to behaviour change techniques, and how users rate these apps. To explore the number of publicly available physical activity apps and relationships among behaviour science techniques, subjective quality, and user ratings. Exploratory content analysis of 17 apps meeting inclusion criteria. The App Behaviour Change Scale (ABACUS) and Mobile App Rating Scale (MARS) were used to code each downloaded app for behaviour change techniques, app functionality, and subjective quality. App store user ratings were also collected along with descriptive data about each app. All apps were commercially affiliated, targeted adult populations, and centered on changing behaviour, setting goals, and addressing physical health. No apps addressed all 21 ABACUS items; apps included 12.8 {+/-} 2.4 indicators, ranging from 8-18 indicators. The three most common ABACUS indicators were: i) collection of baseline information, ii) instructional PA content, and iii) ability for app to give user feedback. The three least common ABACUS indicators were: i) ability to export data, ii) consequences for physical activity dis/continuance, and iii) allows for planning of barriers. No apps included all 12 MARS focus areas; 94.1% of apps allowed goal setting, 58.8% addressed physical health, and 41.2% included a mindfulness focus. Linear regressions explored relationships for app user ratings; aggregated MARS domains accounted for 54% of the variance. Publicly available physical activity apps may be a useful approach to improving physical activity uptake and adherence among harder-to-reach populations including low socioeconomic status groups. App developers should consider incorporating more behaviour change techniques within cost-free apps to improve user uptake and ultimately improve physical activity associated health outcomes. Author SummaryDigital technology proliferates all facets of life and populations, and may contribute to improved health behaviours including physical activity. However, access to supportive technology may be limited by cost for example, as many popular physical activity apps require paid subscriptions. It is unknown whether cost-free physical activity apps adhere to behaviour change recommendations and how these apps are rated by users. This research explored cost-free, publicly available physical activity apps and their respective relationships with behaviour change techniques as well as app-store user ratings. Only 17 apps met inclusion criteria, and were compared against one behaviour change scale and one app quality scale. All apps had commercial motivations and focused on physical activity for adult populations. Most commonly, apps collected user info at baseline, provided physical activity instructional content, and provided feedback to users. Apps were generally rated positively by users based on app-store star ratings. Cost-free physical activity apps may be useful tools for users looking to improve physical activity for individuals who are limited by their socioeconomic situation. However, greater emphasis on evidence-based behaviour change approaches may be necessary to improve health outcomes for users.

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Long-term follow-up of the public health impacts and co-benefits of an urban greenway intervention: A 15-year natural experiment evaluation

Nguyen, D.; Tate, C.; Akaraci, S.; Wang, R.; Kee, F.; Mullineaux, S.; ONeill, C.; Cleland, C.; Murtagh, B.; Ellis, G.; Bryan, D.; Longo, A.; Garcia, L.; Clarke, M.; Hunter, R. F.

2026-04-11 public and global health 10.64898/2026.04.08.26350381 medRxiv
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BackgroundEvidence on the long-term impact of urban green and blue spaces (UGBS) interventions remains limited. This study is a 15-year evaluation of an urban greenway development in Belfast (United Kingdom), assessing the potential effects of this UGBS intervention on physical activity (PA), mental wellbeing and co-benefits. MethodsUsing quasi-experimental design, a repeated cross-sectional survey was conducted in 2010 (baseline), 2017 (post-opening) and 2023 (long-term follow-up) with about 1,200 adults participated each wave. Outcomes included PA, mental wellbeing, general health, quality of life, social capital and environmental perception. Multilevel mixed-effect regressions were performed to examine within-group changes at long-term follow-up. Difference-in-differences analysis investigated the between-group changes that might be attributed to the greenway. Additional comparative analyses included distance-decay analysis and comparison with population trends in Northern Ireland. ResultsAt six years after completion, the greenway intervention appears to buffer a decline in duration of PA - mainly from moderate-intensity activity (decline lower by 118.6 min/week, 95%CI: 3.9-232.2) but with no significant impact on the proportion of the population meeting the recommended PA level. The intervention is associated with a smaller decline in self-rated health (4.98 units; 95%CI: 0.62-9.34) relative to control group. Intervention association with mental wellbeing was positive but not significant (p=0.30). The greenway also showed positive effects on social capital and environmental perceptions, with impacts most evident in improving safety and trust in the local area. ConclusionThis study provides evidence to support the public health impact of UGBS and its long-term health and social benefits.

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Drivers and barriers to the implementation of the school feeding values-based food procurement guidelines and ultra-processed food restrictions

Fernandes Davies, V.; Perrut, I.; Thow, A.-M.; Duran, A. C.

2026-04-24 health policy 10.64898/2026.04.22.26351508 medRxiv
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Objective: To investigate in the National School Feeding Program (PNAE) the local level drivers and barriers to the implementation of four guidelines: the banning of sugary drinks; restrictions on the procurement of processed and ultra-processed foods; the mandatory increase in weekly servings of fruits and vegetables offered to students; and mandatory direct procurement from family farmers. Design: Qualitative study that used semi-structured interviews. Street level bureaucracy theory informed the theoretical framework and thematic analysis. Setting: Brazilian municipalities, across the country five geographic regions (North, Northeast, Southeast, South, and Midwest). Participants: Stakeholders (e.g. nutritionists, school cooks, and food procurement managers) involved in the local implementation of the PNAE program across the country. Results: Ninety stakeholders were interviewed. Stakeholders reported having autonomy to perform their activities, collaboration and support from other members within the local government and food providers, adequate infrastructure such as a well-equipped kitchens, the availability of trained personnel, and political commitment as drivers for optimum program implementation. Reported barriers included lack of support and resistance to change among cooks, teachers and parents; insufficient physical and human resources; and limited political commitment. When barriers outweighed drivers, interviewees reported adapting their practices, often in restrictive ways that could compromise the implementation of the program. Conclusions: Drivers and barriers to local PNAE implementation were generally similar across studied municipalities, although their magnitude varied. In contexts of greater economic vulnerability and fiscal constraint, additional support and targeted actions from the federal government may be required to strengthen local implementation

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Patterns and Clinical Outcomes of Physical Activity and Sedentary Behavior Across 20 Million Days of Wearable Monitoring in U.S. Adults

Nargesi, A. A.; DSouza, V.; Shnitzer, T.; Kadaifciu, A.; Cremer, A.; Jurgens, S. J.; Mack, N.; Lupi, R.; Azuine, R.; Ginsburg, G. S.; Lunt, C.; Anderson, C. D.; Friedman, S.; Maddah, M.

2026-02-12 public and global health 10.64898/2026.02.11.26346079 medRxiv
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BackgroundPhysical activity is a key modifiable determinant of health, yet current guidelines primarily emphasize moderate-to-vigorous physical activity and provide limited guidance on other actionable dimensions such as daily step count and sedentary time. The growing availability of wearables enables high-resolution measurement of these metrics and assessment of their associations with clinical outcomes. MethodsMinute-level wearable data from adult participants of All of Us between 2015-2023 were used to calculate step count and sedentary time. Patterns of step count and sedentary behavior were assessed across temporal scales, U.S. states, and sociodemographic groups. Phenome-wide association (PheWAS) and dose-response analyses were conducted to evaluate associations with incident disease. ResultsAmong 50,300 participants (68% female, 71% White, median age 55 years), 19,845,612 person-days of wearable monitoring over a median follow-up of 13 months were included in this analysis. Step counts peaked at midday with weekly highs on Saturdays and seasonal highs in May, while sedentary time was highest in midafternoon and winter. Higher step counts and lower sedentary time were observed among males, individuals with higher income and education, and residents of the Northeast, upper Midwest, and West Coast. In PheWAS (n=31,446), higher step count and lower sedentary time were associated with lower risk of multiple diseases, including obesity, cardiometabolic risk factors, and mood and anxiety disorders. Dose response analyses demonstrated heterogeneous relationships across disease groups, with cardiovascular benefits plateauing beyond 9,000-10,000 steps/day and below 600-640 minutes/day of sedentary time. ConclusionsIn this nationwide cohort of U.S. adults, wearable-derived physical activity and sedentary behavior showed distinct temporal and geographic patterns with significant disease-specific associations with clinical outcomes. These findings support the use of longitudinal high-resolution wearable data for advancing personalized guidelines of physical activity and sedentary behavior.

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Social, economic, and environmental disparities in device-measured 24-hour movement behaviours in a nationally representative cohort of older English adults

Brocklebank, L.; Steptoe, A.; Bloomberg, M.; Doherty, A.

2026-03-27 public and global health 10.64898/2026.03.25.26349270 medRxiv
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Abstract Background: Insufficient physical activity, excessive sedentary time, and suboptimal sleep are linked to premature mortality and chronic disease and may contribute to social inequalities in health, but most evidence is self-reported. Device-measured, nationally representative data capturing the full 24-hour movement spectrum remain scarce, particularly among older adults. This study examined social, economic, and environmental disparities in 24-hour movement behaviours in the 2021-23 English Longitudinal Study of Ageing (ELSA) accelerometry sub-study. Methods: A subset of 5,382 ELSA participants (71.9%) was invited to wear an Axivity AX3 wrist accelerometer for eight days, with 4,354 (80.9%) agreeing. Raw data were processed using machine learning to derive step count, sleep duration, moderate-to-vigorous and light physical activity, sedentary time, and time in bed. Cross-sectional associations with sex, age, education, marital status, wealth, and urbanicity were examined using linear regression. Findings: Data from 3,648 participants (mean age 68.5 {+/-} 9.3 years; 44.3% men) were included in wear time analyses (median 6.6 days, IQR 6.0-6.9), with 3,161 (86.7%) having sufficient wear time for movement behaviour analyses. Older, unmarried, or lower education/wealth participants were less active, more sedentary, and slept less. Rural participants were more active than urban participants. Women accumulated fewer steps and less moderate-to-vigorous physical activity and sedentary time, but more light activity and longer sleep than men. Interpretation: Social, economic, and environmental disparities exist across the full 24-hour movement spectrum, highlighting population groups for targeted interventions. Follow-up data will clarify how 24-hour movement behaviours influence healthy ageing and contribute to social inequalities in health.

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Effectiveness of an automated text message intervention for weight management in postpartum women with overweight or obesity (Supporting MumS (SMS)): a UK wide, multicentre, two arm, parallel group, randomised controlled trial.

Gallagher, D.; Spyreli, E.; Calder-MacPhee, N.; Crossley, K.; Feuillatre, C.; Ivory, A.; Karatas, B.; Kelly, C. B.; Lind, M.; Osei-Asemani, E.; Potrick, R.; Stanton, H.; Bridges, S.; Coulman, E.; Free, C.; Hoddinott, P.; Anderson, A. S.; Cardwell, C. R.; Dombrowski, S. U.; Heaney, S.; Kee, F.; McDowell, C.; McIntosh, E.; Murphy, L.; Woodside, J. V.; McKinley, M. C.

2026-03-06 public and global health 10.64898/2026.03.05.26347713 medRxiv
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ObjectiveTo test the effectiveness of a postpartum behavioural intervention delivered by automated text messaging in reducing weight. DesignTwo parallel group, multicentre, randomised controlled trial. SettingRecruitment from five areas across the United Kingdom (Belfast, Bradford, Stirling, London and Cardiff) through healthcare and community pathways, including social media. ParticipantsA diverse sample of 892 women between 6 weeks and 24 months postpartum, aged 18 years or more and with a body mass index of 25 kg/m2 or more, enrolled between May 2022 and May 2023: 445 were randomised to the intervention and 447 to an active control (comparator). InterventionsTwelve months of fully automated text messages with embedded behaviour change techniques and two-way messaging components to support weight loss and maintenance of weight loss in the postpartum period by targeting dietary, physical activity and weight management behaviours. The comparator group received 12 months of text messages on child health and development tailored to child age. Main outcome measuresPrimary outcome - weight in kilograms at 12 months (end of intervention). Secondary outcomes recorded at 6 and 12 months were changes in weight (at 6 months), body mass index, proportions of women with weight gain or loss of 5 kg or more, waist circumference, self-reported dietary intake, physical activity and infant feeding practices. Results674 (75.6%) participants were included in the primary analysis. There was no statistically significant difference found in the adjusted mean weight change between the intervention and active control groups (-0.1 kg (95% confidence interval -1.0 to 0.8, P= 0.84). Sensitivity analyses did not change these results. There was a small statistically significant improvement in Fat and Fibre Barometer scores at 12 months in the intervention compared with control group (adjusted mean difference 0.09, 95% CI: 0.04 to 0.14; P <0.001) and a statistically significant increase in physical activity scores (International Physical Activity Questionnaire - Short Form) at 12 months in the intervention group compared with the control group (adjusted mean difference 405.3 total MET minutes/week, 95% CI: 141.3 to 669.3; P= 0.003). ConclusionsA 12 month automated, interactive behavioural weight management intervention delivered by text message did not support weight loss for postpartum women but did have a positive impact on diet and physical activity behaviours. WHAT IS ALREADY KNOWN ON THIS TOPICWomen desire support with self-care behaviours such as diet, physical activity and weight management in the postpartum period, but little support is currently available. There is a lack of acceptable and effective weight management interventions designed for women during the postpartum period. Most previous studies in the field have been affected by poor recruitment, high rates of attrition, lack of diversity and have not adequately considered the lived experience of women. Mobile technologies can offer a more flexible and individualised any time, any place approach to behavioural weight management interventions that may be well suited to this stage of life. WHAT THIS STUDY ADDSThe trial methodology was highly acceptable to postpartum women and recruitment and retention targets were met. Overall, a fully automated two-way text message intervention did not support weight loss in a diverse sample of postpartum women from the United Kingdom but did support positive changes in diet, physical activity and infant feeding behaviours. Pre-specified engagement analysis showed that women who engaged most with the intervention did lose weight. There was no differential effect of the intervention across socioeconomic or ethnic groups.

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Leisure-time physical activity on lifelong trajectories of body mass index and obesity risk throughout life: multivariable regression and Mendelian randomization analyses using real-world data from the CORDELIA-Catalunya Study

Hernando Redondo, J.; Camps-Vilaro, A.; Elosua, R.; Fornara, E.; Bermudez-Lopez, M.; Toran-Monserrat, P.; Jimenez-Navarro, A.; Valdivielso, J. M.; Lopez-Lifante, V. M.; Salas-Fernandez, T.; Cambray, S.; Cruz, R.; Marrugat De La Iglesia, J.; Hernaez, a.

2026-02-25 epidemiology 10.64898/2026.02.23.26346892 medRxiv
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BackgroundEvidence on how leisure-time physical activity (LTPA) improves lifetime body mass index (BMI) remains fragmented and prone to confounding. MethodsWe pooled 14,993 adults (30-90 y; 52.7% women; cohorts: REGICOR-ACRISC, ILERVAS, ARTPER) with baseline estimated LTPA (moderate-to-vigorous LTPA [MVLTPA] in REGICOR-ACRISC), genotype, and repeated BMI values from electronic health records (1990-2024, 36,157 measures). LTPA was categorized into cohort-specific quartiles; MVLTPA in 0, <100, <200, and [&ge;]200 METs-min/day. In one-sample Mendelian randomization analyses, we categorized participants in quartiles of a cardiorespiratory fitness polygenic risk score derived from a large GWAS in UK Biobank. Group-dependent BMI trajectories were modeled using spline mixed-effects models. Obesity onset (first BMI [&ge;]30 kg/m2) was analyzed with IPW-weighted Kaplan-Meier curves and Cox models. ResultsHigher LTPA was associated with slower BMI increases in ages 30-60 (Q1: +0.120 vs Q4: +0.075 kg/m2{middle dot}year), slower declines in ages 70-90 (Q1: -0.143 vs Q4: -0.123 kg/m2{middle dot}year), and lower obesity risk (Q4 vs Q1: HR 0.83, 95% CI 0.72-0.96). Similar trends were observed for MVLTPA. Higher genetically determined cardiorespiratory fitness showed parallel gradients (ages 30-60, Q1: +0.109 vs Q4: +0.101 kg/m2{middle dot}year; ages 70-90, Q1: -0.130 vs Q4: -0.102 kg/m2{middle dot}year) and lower obesity risk (Q4 vs Q1: HR 0.66, 0.56-0.78). Associations were present for women and men separately, but were stronger in men. ConclusionsHigher LTPA and MVLTPA were associated with more favorable lifelong BMI trajectories, delayed obesity risk, and convergent support from Mendelian randomization analyses, supporting a causal protective role of physical activity (in both sexes but stronger in men).

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Changes in health inequalities following a major urban greenway intervention: Evidence from a 15-year natural experiment in the UK

Nguyen, D.; ONeill, C.; Akaraci, S.; Tate, C.; Wang, R.; Garcia, L.; Kee, F.; Hunter, R. F.

2026-04-12 public and global health 10.64898/2026.04.08.26350389 medRxiv
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HighlightsO_LIHealth inequalities have widened over 15 years, favouring high-income groups C_LIO_LIInequality in physical activity & mental health widened the most pre-intervention C_LIO_LIPost-intervention, inequalities persisted but stayed relatively unchanged. C_LIO_LILong-term illness and unemployment were key drivers of inequality C_LIO_LIThe greenway may have slowed down the inequality widening but the impact is limited C_LI BackgroundEvidence concerning health inequalities following urban green and blue space UGBS) interventions is limited. This study examined the changes in health inequalities after a major urban regeneration project, the Connswater Community Greenway (CCG), in Belfast, UK. MethodCross-sectional household surveys were conducted in 2010/11 (baseline), 2017/18 (immediately after completion), and 2023/24 (long-term follow-up) with a sample of approximately 1,000 adults each wave. Using concentration indices (CI), income-related health inequalities for three outcomes (physical activity, mental wellbeing and quality of life) were measured. A regression-based decomposition of concentration index examined the contribution of sociodemographic factors to the observed inequalities underpinning each outcome over time. ResultsAcross three waves, there was widening of inequalities over the 15-year period across all three health outcomes, with those from high-income groups reported higher levels of physical activity (CI=0.33, SE=0.026), better mental wellbeing (CI=0.03, SE=0.003), and better quality of life (CI=0.09, SE=0.008). The widening inequalities mainly occurred during the construction phase of CCG (2010-2017) and remained stable post-intervention (2017-2023). Decomposition analysis revealed that the pro-poor concentration of long-term illness and unemployment was the key driver that together explained approximately 51%-76% of the inequalities. ConclusionThe CCG was limited in reducing health inequalities which were mainly driven by long-term illness and unemployment - factors beyond the direct scope of the UGBS intervention - resulting in low-income groups likely to fall further behind the wealthier groups. The widening of inequality is consistent with findings from other public interventions that did not have a primary equity focus.

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How have restaurant menus changed following England's calorie labelling regulations and who is likely to benefit? A longitudinal analysis of online menu

Kalbus, A.; Kumar, R.; Rinaldi, C.; Curtin, E.; King, J.; Reynolds, P.; Cornelsen, L.; Essman, M.

2026-01-29 nutrition 10.64898/2026.01.27.26344846 medRxiv
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BackgroundThe introduction of mandatory calorie labelling among large food businesses (chains) in England in 2022 has been found to have little impact on consumer behaviour, but overall calories on restaurant menus have decreased slightly. This study examined menu changes post policy implementation, and the population groups likely to have been affected most. MethodsMenu data from 169 chains in Great Britain were extracted from two online food delivery platforms in June 2022 and June 2023. We selected 10 categories (specific foods or chains) jointly with public and policy advisors. Menu changes over time were assessed with multilevel models accounting for whether an item was continuously on the menu and for the type of chain. Where changes were found, we assessed differences in purchasing frequency by consumer characteristics using 2022 OOH purchase data (Worldpanel by Numerator, GB OOH Panel). ResultsChanges were observed in two (out of 10) categories examined and were driven by changing items on the menu rather than reformulating continuous dishes. Chains that used a healthy tag on the delivery website increased the share of mains under 600 kcal by 3.7 percentage points (95% CI 0.2 to 7.2), while average calories did not change (-17.6 kcal/item, 95% CI -38.7 to 3.4). Men, people aged 35-44 years and with high SES were found to purchase more frequently from these chains. Across all chains, the share of lower-calorie coffees decreased by 10 pp (95% CI -18.0 to - 0.02), with purchasing more frequent among men and increasing with age. ConclusionsAlthough data were available for one year only post-policy implementation, menu changes among the investigated foods and chains were limited. While menu change may equitably improve population dietary health, dietary inequalities may exacerbate if only healthy chains already offering lower-calorie food change their menus.

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The causal relationships between leisure-time physical activity and body mass index in adulthood: A triangulation study

Kankaanää, A.; Joensuu, L.; Ekelund, U.; Pitkänen, A.; Waller, K.; Palviainen, T.; Kaprio, J.; Ollikainen, M.; Aaltonen, S.; Sillanpää, E.

2026-03-11 public and global health 10.64898/2026.03.10.26348015 medRxiv
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BackgroundPrevious studies have presented conflicting findings regarding the potential causal relationships between leisure-time physical activity (LTPA) and body mass index (BMI). Here, we use individual-level data and apply a triangulation framework that incorporates three complementary methods to investigate the bidirectional causal associations between LTPA and BMI. MethodsWe used data from a longitudinal Finnish twin cohort with four measurement points spanning 36 years. The data included 22,696 twin individuals aged 18-50 years at baseline (52.4% women); 8,527 had genetic data available. We applied three analytical approaches suggested to strengthen causal inference in observational studies: Random intercept cross-lagged path model (RI-CLPM) for longitudinal data, one-sample Mendelian Randomization (MR) and Direction of Causation (DoC and MR-DoC) twin models for cross-sectional data at each measurement point. ResultsAll three approaches provided evidence for a causal effect of higher BMI on lower LTPA, particularly at the later follow-up stages. Only twin models suggested a negative causal effect of LTPA on BMI. Men and women showed mainly similar effects. ConclusionsEvidence triangulation across the three methodologies provided support for a causal effect of higher BMI on lower LTPA, whereas the evidence for a reverse effect was less convincing. Our results indicate that the role of high BMI in limiting LTPA becomes more important with advancing age, while also highlighting the importance of accounting for timing when studying the causal effects of LTPA on BMI and vice versa.

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Dietary patterns and nutritional composition of packed lunches in early years education settings

Deb, S.; Wisbey, M.; Hawkins, M.; Randall, S.; Harris, M.; Aaronricks, K.

2026-03-04 nutrition 10.64898/2026.03.03.26347536 medRxiv
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BackgroundPacked lunches are a common feature of early childhood food provision, yet evidence describing their nutritional composition in early years settings remains limited. Understanding the foods provided during this developmental period is important, given the potential influence of early dietary exposures on later health. AimTo characterise the composition, nutritional quality, cost, and dietary patterns of packed lunches brought from home in Early Childhood Education and Care settings, and to examine variation by child age and area-level deprivation. MethodsA cross-sectional analysis was conducted using a remote food photography method to assess packed lunches provided for children aged 1-4 years attending early years settings across Essex, UK. Food items were categorised into predefined groups, and nutrient composition was estimated. Area-level deprivation was determined using the English Index of Multiple Deprivation (2019). Non-parametric tests assessed between-group differences. Principal components analysis (PCA) was used to identify patterns of co-occurring foods. ResultsA total of 389 packed lunches were analysed. Starchy foods (82%), fruit (81%), dairy or alternatives (72%), and savoury snacks (74%) were commonly provided, while vegetables were less frequent and fish was rarely observed (1.5%). Overall, 97.7% of lunches contained at least one ultra-processed food (UPF), with a median of three UPF items per lunch and 74% of total energy derived from UPFs. Median energy provision was 400 kcal (IQR 309-518). Nutrient composition was broadly similar across deprivation groups, although cake and biscuit counts and UPF item counts were modestly higher in more deprived areas. The median estimated lunch cost was {pound}1.79 and did not differ by deprivation. ConclusionsPacked lunches in early years settings frequently contained ultra-processed foods and showed considerable variability in nutritional quality. Socioeconomic differences were limited, suggesting that contemporary packed lunch practices may reflect influences operating across population groups. Further research across diverse regions is warranted to better understand the provision of packed lunches and their implications for early dietary exposure.

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Reallocation of 24-hour physical behaviour composition and mortality: exploring effect modification by sleep characteristics

Bian, W.; Ahmadi, M.; Mitchell, J. J.; Biswas, R. K.; Koemel, N. A.; Dumuid, D.; Chastin, S. F.; Blodgett, J. M. F.; Chaput, J.-P.; Hamer, M.; Stamatakis, E.

2026-03-25 epidemiology 10.64898/2026.03.23.26349126 medRxiv
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Time compositions of physical behaviours are associated with premature mortality, but the moderating role of sleep remains unclear. Using data from the UK Biobank accelerometry subsample, we examined associations of time reallocations between five device-measured physical behaviours (sleep, sedentary behaviour (SB), standing, light-intensity (LPA) and moderate-to-vigorous physical activity (MVPA)) with all-cause, cardiovascular disease (CVD) and physical activity-related cancer mortality, and the potential effect modification by sleep duration and regularity. Compositional Cox regression was used to examine associations of behavioural reallocations with mortality. In 58,149 adults, 2,209 deaths occurred over a mean follow-up of 8.0 years. Among participants who meet sleep duration guidelines, reallocating 30 minutes from sleep to standing, LPA or MVPA was favourably associated with all-cause mortality with HRs of 0.86 (95%CI 0.79, 0.93), 0.87 (0.80, 0.95), and 0.80 (0.73, 0.87), respectively. Reallocating 30 minutes from sleep to SB, standing, or LPA was adversely associated with CVD risk (HRs 1.08 (1.02, 1.15), 1.10 (1.01, 1.20), and 1.11 (1.03, 1.20)) among those not meeting guidelines. Beneficial associations of reallocating SB to sleep were evident only amongst short (<7h/day) or regular (SRI>87.8) sleepers across mortality outcomes. Our findings support incorporating sleep characteristics into future personalised behavioural interventions design and behavioural targets.

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Physical activity and body mass index inequities among adult women in the United States: An application of intersectional multilevel analysis of individual heterogeneity and discriminatory accuracy (I-MAIHDA)

Echeverria, S.; Seo, Y.; Borrell, L. N.; McKelvey, D.; Najjar, T.; Reifsteck, E. J.; Erausquin, J. T.; Maher, J. P.

2026-04-07 epidemiology 10.64898/2026.04.06.26350273 medRxiv
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Background Physical activity (PA) and body mass index (BMI) shape cardiovascular risk, particularly in women. Yet, little research exists examining intersectional social axes shaping PA and BMI inequities among women living in the United States (US). Methods Data included women sampled in the 2015-2020 National Health and Nutrition Examination Survey. We used Intersectional Multilevel Analysis of Individual Heterogeneity and Discriminatory Accuracy (I-MAIHDA) via linear models to examine PA (n=,4591) and BMI (n=4,596) inequities across intersectional strata defined by race/ethnicity, age, education, nativity, and work status. We further quantified the contribution of these strata to the observed inequities and estimated additive fixed effects. Results In the null model, intersectional strata explained 4.6% and 13.8% of the variance in PA and BMI inequities, respectively, with 99.2% for PA and 97.5% for BMI explained by age, race/ethnicity, education, nativity, and occupation status. On average, Asian and Black women, those aged 35-49 years, those born outside the US, and those with less than a high school diploma had the lowest predicted mean PA. For BMI, Black and Hispanic/Latino women and those younger than 64 years had the highest mean BMI. Conclusion PA and BMI inequities are mostly explained by race/ethnicity, age, education, nativity, and work status. Our findings offer insights into universal and potential policy-informed health promotion strategies that may be tailored to women with these social identities and lived experiences that have shaped physical activity and body mass index inequities.

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Nutritional availability and carbon footprints of vegetarian and vegan diets: a cross-sectional analysis of dietary data for UK children

Coffey, A.; Lillywhite, R.; Oyebode, O.

2026-01-30 nutrition 10.64898/2026.01.28.26345075 medRxiv
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As plant-based (PB) diets become more common among UK children, understanding their nutritional adequacy and environmental impact is vital. This study assessed nutrient intake and dietary greenhouse gas emissions among children following omnivorous, vegetarian, and vegan diets. A cross-sectional analysis was conducted using three-day weighed food diaries from 39 UK children aged 2-12 years (omnivore n=15; and PB: vegetarian n=11; vegan n=13). Nutrients were analysed with and without supplementation using Nutritics software. GHGEs were calculated at the ingredient level (kgCO2e/day) and grouped by Eatwell Guide food categories. No dietary group met all nutrient reference values. Omnivores exceeded recommended intakes for saturated fat and free sugars while failing to meet the recommended intake for fibre, whereas PB children had intakes of these nutrients in the healthy range. PB diets were adequate in protein and vitamin B12 even in the absence of supplementation. Vegan children also met iron requirements from diet alone, whereas omnivore and vegetarian children did not meet iron targets without supplementation. Vitamin D intake was insufficient across all groups when supplements were excluded, with only vegan children achieving recommended levels through supplementation. Zinc requirements were met only by vegetarian children with the aid of supplements and were not met by vegan or omnivore children with or without supplementation. Iodine intake remained inadequate in vegan children even with supplementation. Mean daily GHGEs differed significantly between diet groups (p < 0.001): omnivores having the highest emissions, while vegans had the lowest emissions: 46% lower than omnivores, and 20% lower than vegetarians. Well-planned PB diets can meet most nutrient needs in UK children when supported by fortified foods and supplements, while substantially reducing dietary GHGEs compared with omnivorous diets. Shifting away from animal protein and dairy provides the greatest opportunity for improving both nutritional quality and environmental sustainability.

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Sustainability and nutritional composition of food choices in hospital canteens: a pre-post intervention study

Mansutti, E.; Fiori, F.; Menis, D.; Cautero, P.; Graziani, C. L.; Zago, D.; Driutti, M.; Lesa, L.; Grillone, L.; Cortelazzo, F.; Cosolo, A.; Mauro, M.; Scarpis, E.; Conte, A.; Parpinel, M.; Brunelli, L.

2026-04-05 public and global health 10.64898/2026.04.02.26349952 medRxiv
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Background: Hospital canteens provide an effective setting for improving the dietary habits of users. The study evaluates the food choices of users after an educational and environmental intervention, considering nutritional composition and environmental impact, and to compare the results with pre-intervention choices. Methods: A cross-sectional study was conducted in three hospital canteens (C1, C2, C3) in northeastern Italy, during two index weeks in September 2022 (T0) and 2023 (T1). An intervention was introduced between T0 and T1, consisting of posters on healthy eating, descriptive norm messages, and environmental changes regarding fruit and vegetables. Photos of lunch trays were collected, and choices were analyzed for nutritional composition and sustainability. Results: 2,851 trays were analyzed: 1,227 at T0 (798 in C1, 228 in C2 and 201 in C3) and 1,624 at T1 (1,005 in C1, 348 in C2, 271 in C3). In C1 and C3, there was an increase in median energy (+30 kcal; +135 kcal) compared to pre-intervention meals, while in C2 there was a decrease (-118 kcal). Despite a slight improvement in macronutrient composition, at T1 meals in all canteens were still high in lipids (30%E; 39%E; 35%E) and low in carbohydrates (44%E; 39%E; 41%E). The fibre value fell within the recommended range only in C1 and C3. The median carbon (CF) and water (WF) footprints of meals in all canteens remained high: at T1 CF ranged from 966 gCO2eq. to 1,227 gCO2eq. and WF from 1,025 L H2O to 1,207 L H2O. Conclusion: The intervention has led to partial improvements in food choices. To achieve more significant results, it may be necessary to implement a parallel intervention on food offer.