Impact of feedback generation and presentation on self-monitoring behaviors, dietary intake, physical activity, and weight: a systematic review and meta-analysis.

Self-monitoring of dietary intake, physical activity, and weight is a key strategy in behavioral interventions, and some interventions provide self-monitoring feedback to facilitate goal setting and promote engagement. This systematic review aimed to evaluate whether feedback increases intervention effectiveness, and which forms of feedback presentation (e.g., personalized vs. not personalized) and generation (i.e., human vs. algorithm-generated) are most effective. To achieve this aim, 5 electronic databases (PubMed/MEDLINE, Web of Science, CINAHL, PsycINFO, and Google Scholar) were searched in April 2022 and yielded 694 unique records, out of which 24 articles reporting on 19 studies were included (with a total of 3261 participants). Two reviewers independently screened titles and abstracts and then full texts and categorized articles as eligible or excluded according to the pre-registered criteria (i.e., availability of full text, peer reviewed manuscript in English; adult participants in a randomized controlled trial that included both self-monitoring and feedback; comparisons of different forms of feedback or comparisons of feedback vs. no feedback; primary outcomes of diet, physical activity, self-monitoring behavior, and/or weight). All included studies were assessed for methodological quality independently by two reviewers using the revised Cochrane risk-of-bias tool for randomized studies (version 2). Ten studies compared feedback to no feedback, 5 compared human- vs. algorithm-generated feedback, and the remaining 4 studies compared formats of feedback presentation (e.g., frequency, richness). A random effects meta-analysis indicated that physical activity interventions with feedback provision were more effective than physical activity interventions without feedback (d = 0.73, 95% CI [0.09;1.37]). No meta-analysis could be conducted for other comparisons due to heterogeneity of study designs and outcomes. There were mixed results regarding which form of feedback generation and presentation is superior. Limitations of the evidence included in this review were: lack of details about feedback provided, the brevity of most interventions, the exclusion of studies that did not isolate feedback when testing intervention packages, and the high risk of bias in many studies. This systematic review underlines the importance of including feedback in behavioral interventions; however, more research is needed to identify most effective forms of feedback generation and presentation to maximize intervention effectiveness.Trial registration (PROSPERO)CRD42022316206.

Consumers' perception of novel foods and the impact of heuristics and biases: A systematic review.

According to the definition adopted in the European Union, novel foods are foods that were not consumed to a significant degree within the Union before May 15, 1997. This includes cultivated meat and insects. Novel foods are meant to play a critical role in the transition towards sustainable food systems. However, their success depends on whether and to what extent they will be incorporated into the diets at the population level. This review investigates consumers' perception of novel food products by narratively synthesising results on the influence of heuristics and biases triggered by emotions, personality traits, and socio-cultural factors. Empirical studies conducted in Western countries and published in English after 1997 were eligible, which led to 182 studies being included. Notably, most included studies focused on insects and cultivated meat. Disgust and fear are shown to be the main emotions driving rejection of novel foods, together with food neophobia and specific cultural norms common across countries included in the scope of the review. Familiarity with novel foods and curiosity both led to higher acceptance. Despite being investigated directly in a minority of studies, heuristics and related biases mostly fell under the "affect," the "natural-is-better," and the "trust" heuristics. The review also discusses to what extent consumers' perception reflects in the regulatory framework applicable to novel foods in the European Union, how it influences the regulation of insects and cultivated meat and which lessons can be drawn for the future of the regulatory framework.

Reducing intervention- and research-induced inequalities to tackle the digital divide in health promotion.

Social inequalities are an important contributor to the global burden of disease within and between countries. Using digital technology in health promotion and healthcare is seen by some as a potential lever to reduce these inequalities; however, research suggests that digital technology risks re-enacting or evening widening disparities. Most research on this digital health divide focuses on a small number of social inequality indicators and stems from Western, educated, industrialized, rich, and democratic (WEIRD) countries. There is a need for systematic, international, and interdisciplinary contextualized research on the impact of social inequality indicators in digital health as well as the underlying mechanisms of this digital divide across the globe to reduce health disparities. In June 2023, eighteen multi-disciplinary researchers representing thirteen countries from six continents came together to discuss current issues in the field of digital health promotion and healthcare contributing to the digital divide. Ways that current practices in research contribute to the digital health divide were explored, including intervention development, testing, and implementation. Based on the dialogue, we provide suggestions for overcoming barriers and improving practices across disciplines, countries, and sectors. The research community must actively advocate for system-level changes regarding policy and research to reduce the digital divide and so improve digital health for all.

Plate size and food consumption: a pre-registered experimental study in a general population sample.

BACKGROUND: There is considerable uncertainty regarding the impact of tableware size on food consumption. Most existing studies have used small and unrepresentative samples and have not followed recommended procedures for randomised controlled trials, leading to increased risk of bias. In the first pre-registered study to date, we examined the impact on consumption of using larger versus smaller plates for self-served food. We also assessed impact on the underlying meal micro-structure, such as number of servings and eating rate, which has not previously been studied. METHODS: The setting was a purpose-built naturalistic eating behaviour laboratory. A general population sample of 134 adult participants (aged 18-61 years) was randomly allocated to one of two groups varying in the size of plate used for self-serving lunch: large or small. The primary outcome was amount of food energy (kcal) consumed during a meal. Additionally, we assessed impact on meal micro-structure, and examined potential modifying effects of executive function, socio-economic position, and sensitivity to perceptual cues. RESULTS: There was no clear evidence of a difference in consumption between the two groups: Cohen's d = 0.07 (95% CI [- 0.27, 0.41]), with participants in the large plate group consuming on average 19.2 (95% CI [- 76.5, 115.0]) more calories (3%) compared to the small plate group (large: mean (SD) = 644.1 (265.0) kcal, versus small: 624.9 (292.3) kcal). The difference between the groups was not modified by individual characteristics. There was no evidence of impact on meal micro-structure, with the exception of more food being left on the plate when larger plates were used. CONCLUSIONS: This study suggests that previous meta-analyses of a low-quality body of evidence may have considerably overestimated the effects of plate size on consumption. However, the possibility of a clinically significant effect - in either direction - cannot be excluded. Well-conducted trials of tableware size in real-world field settings are now needed to determine whether changing the size of tableware has potential to contribute to efforts to reduce consumption at population-level. TRIAL REGISTRATION: The study protocol ( https://osf.io/e3dfh/ ) and data analysis plan ( https://osf.io/sh5u7/ ) were pre-registered on the Open Science Framework.

Boosting healthy food choices by meal colour variety: results from two experiments and a just-in-time Ecological Momentary Intervention.

BACKGROUND: Dietary guidelines typically specify rather complex goals and indicators for healthy food choices, such as nutrient and energy content patterns. However, translating these complex goals into practice in real life is often a major obstacle for many people. The present studies propose an intervention strategy for boosting healthy food choices by prompting consumers at a meaningful moment with a simple behavioural trigger, that is to eat a colourful lunch. Effectivity and feasibility of this intervention strategy were tested in two laboratory experiments and one real-life, smartphone-based Ecological Momentary Intervention. METHODS: In Studies 1 and 2, 83 / 42 participants self-served four meals (colourful, typical, healthy, and low-calorie) / three meals (colourful, typical, and varied) from a Fake Food Buffet. In Study 3, 80 participants recorded images of 1,210 lunch meals over a period of 3 weeks using mobile visual food recording. In the second week, participants additionally received a daily smartphone prompt to eat a colourful lunch. In all studies, participants were asked to rate the prompts' feasibility. RESULTS: Prompting participants to eat a colourful meal increased the proportion of healthy foods consumed compared to typical meals in all three studies. In Studies 1 and 2, colourful meals contained more fruit and vegetables, while in Study 3 the prompt increased vegetable consumption. Furthermore, participants evaluated colourful meals to be the tastiest (Study 1) and most pleasant, and reported that the prompt was easy to follow and act upon. CONCLUSIONS: Results suggest that prompting individuals to eat colourful meals is a promising strategy to facilitate healthy food choices in daily life. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00017552 (Study 3; retrospectively registered on 24th June 2019).

The social image of food: Associations between popularity and eating behavior.

One factor that determines what we eat and why we eat is our social environment. In the present research, two online studies examined the relationship between food intake and social images. Specifically, the present research assessed the relationship between the food intake university students ascribed to peers who varied in popularity and own self-reported food intake, and whether this relationship was moderated by identification with the peer group. Participants (N = 97 in Study 1; N = 402 in Study 2) were randomly presented with one of four (Study 1) or two of eight (Study 2) vignettes describing a popular or unpopular student (male or female) from their university without receiving any information about the peer's eating behavior. Subsequently, healthy and unhealthy eating ascribed to the peers and own self-reported eating behavior were assessed. Results indicated that popular peers were perceived to eat more healthily than unpopular peers. Moreover, eating behavior ascribed to popular peers were associated with own healthy and unhealthy eating. Importantly, the relationship between healthy eating behavior ascribed to popular peers and own healthy eating behavior was moderated by identification with the student group - the more participants identified with their peers, the more their own eating was aligned with the healthy eating ascribed to a popular peer. Hence, the popularity of others seems to shape perceptions of the food they eat and may facilitate healthy eating via social influence.

Digital health interventions for all? Examining inclusivity across all stages of the digital health intervention research process.

Digital interventions offer many possibilities for improving health, as remote interventions can enhance reach and access to underserved groups of society. However, research evaluating digital health interventions demonstrates that such technologies do not equally benefit all and that some in fact seem to reinforce a "digital health divide." By better understanding these potential pitfalls, we may contribute to narrowing the digital divide in health promotion. The aim of this article is to highlight and reflect upon study design decisions that might unintentionally enhance inequities across key research stages-recruitment, enrollment, engagement, efficacy/effectiveness, and retention. To address the concerns highlighted, we propose strategies including (1) the standard definition of "effectiveness" should be revised to include a measure of inclusivity; (2) studies should report a broad range of potential inequity indicators of participants recruited, randomized, and retained and should conduct sensitivity analyses examining potential sociodemographic differences for both the effect and engagement of the digital interventions; (3) participants from historically marginalized groups should be involved in the design of study procedures, including those related to recruitment, consent, intervention implementation and engagement, assessment, and retention; (4) eligibility criteria should be minimized and carefully selected and the screening process should be streamlined; (5) preregistration of trials should include recruitment benchmarks for sample diversity and comprehensive lists of sociodemographic characteristics assessed; and (6) studies within trials should be embedded to systematically test recruitment and retention strategies to improve inclusivity. The implementation of these strategies would enhance the ability of digital health trials to recruit, randomize, engage, and retain a broader and more representative population in trials, ultimately minimizing the digital divide and broadly improving population health.

Debunking nutrition myths: An experimental test of the 'truth sandwich' text format.

OBJECTIVES: Myths about diet and nutrition are widespread and may seriously impact health and well-being. This study tests whether texts in a truth sandwich format, that is, texts presenting two blocks of factual, correcting information around a text block listing a myth and identifying it as false, are effective in reducing agreement with a range of nutrition myths. DESIGN: Prestudy: observational survey; main study: 4 Text × 6 statement mixed experimental design. METHODS: Out of 13 nutrition myths that were presented to 58 participants in a prestudy, the six most prevalent myths were selected for the main study. In the preregistered main study, 302 participants were randomly assigned to either reading one of three texts in the truth sandwich format addressing a nutrition myth or reading a text about healthy eating (control condition) before rating their agreement with a total of six nutrition myths. RESULTS: Participants agreed less with the specific myth targeted by the truth sandwich text, while controls were not differentiating between them. CONCLUSIONS: Thus, truth sandwiches are effective in reducing agreement with myths and can be harnessed to promote evidence-based dietary practices to promote health in the population.

Investigation of Ukrainian refugees' eating behavior, food intake, and psychological distress: Study protocol and baseline data.

Since the start of the war in Ukraine, almost 8 million people left the country; more than 1 million of them relocated to Germany. It is to be expected that the war puts considerable strain on refugees, which will impact the public health system in host countries. This paper presents baseline data and protocol of longitudinal online experimental study of 619 Ukrainian refugees in Germany started in autumn 2022, focusing on participants' self-reports of appetite, food intake, and levels of stress, anxiety, and depressive symptoms to examine their associations. Results indicate that levels of stress, anxiety, and depressive symptoms in refugees significantly exceed the indicators of relevant parameters as reported by independent large-scale surveys conducted in Ukraine before the war as well as strong correlations between these deviations (.59 ≤ r ≤ .69, p = .005). Changes in appetite were related to more severe psycho-emotional deviations (.15 ≤ r ≤ .19, p = .003) and somewhat unhealthier food intake (r = -.08, p < .001). The study underlines the need of psychological care for refugees to improve their mental health and counteract potential negative consequences for physical health via changes in food intake, for which suitable interventions need to be developed.

Does the medium matter? Comparing the effectiveness of videos, podcasts and online articles in nutrition communication.

Videos and podcasts have become popular in nutrition communication. However, it is unclear whether they are more effective than online texts in conveying knowledge and promoting behavioural intentions. Based on the Cognitive Theory of Multimedia Learning, it was hypothesised that videos are more effective than podcasts or texts in communicating nutrition-related information. In addition, differences in behaviour change intentions were explored. The pre-registered online experiment used a 3 (medium: video, podcast and text) × 3 (topic: diet and climate change, sugar content, and nudging) between-subjects design with 320 participants who were randomly assigned to the conditions. After receiving the respective content, the participants' intention to change their behaviour accordingly and their knowledge about all topics were assessed. A mixed Analysis of Variance revealed a significant interaction of topic and knowledge, indicating that knowledge was higher for the topic that participants were assigned to, compared to the two topics they received no information about. There were no differences in knowledge or intention for the three media. Videos, podcasts and texts are equally suitable for conveying nutrition knowledge and may also be equally beneficial for promoting intention. Communicators may thus base their choice of medium on considerations like available resources and preferences of the target group.

Do nutrition knowledge, food preferences, and habit strength moderate the association between preference for intuition and deliberation in eating decision-making and dietary intake?

An intuitive style in eating decision-making, for example, basing decisions on one's gut feeling, has been related to a less healthy diet, whereas deliberately deciding what to eat, such as making plans about eating behavior, has been related to a healthier diet. The present study investigated whether nutrition knowledge, food preferences, and habit strength for healthy and unhealthy eating moderate these relationships. In total, 1245 participants took part in a preregistered cross-sectional online survey. Results revealed that neither nutrition knowledge, nor liking of healthy or unhealthy foods, nor habit strength for healthy or unhealthy eating interacted with the preference for intuition or deliberation in eating decision-making in affecting dietary intake (ßs ≤ |.06|; ts ≤ |2.11|; ps ≥ .035). Instead, including the potential moderating variables in analyses rendered the effect of a preference for intuition largely non-significant. In contrast, the positive effect of a preference for deliberation was largely stable even when including the potential moderating variables. Thus, the present study confirms the general health-promoting effect of a preference for deliberation in eating decision-making. In contrast, results speak in favor of a generally minor role of a preference for intuition for healthy or unhealthy eating.

How to debunk misinformation? An experimental online study investigating text structures and headline formats.

OBJECTIVES: Misinformation is a crucial problem, particularly online, and the success of debunking messages has so far been limited. In this study, we experimentally test how debunking text structure (truth sandwich vs. bottom-heavy) and headline format (statement vs. questions) affect the belief in misinformation across topics of the safety of COVID vaccines and GMO foods. DESIGN: Experimental online study. METHODS: A representative German sample of 4906 participants were randomly assigned to reading one of eight debunking messages in the experimentally varied formats and subsequently rated the acceptance of this message and the agreement to misinformation statements about the mentioned topics and an unrefuted control myth. RESULTS: While the debunking messages specifically decreased the belief in the targeted myth, these beliefs and the acceptance of the debunking message were unaffected by the text structures and headline formats. Yet, they were less successful when addressing individuals with strong pre-existing, incongruent attitudes and distrust in science. CONCLUSIONS: The risk of backfire effects in debunking misinformation is low. Text structure and headline format are of relatively little importance for the effectiveness of debunking messages. Instead, writers may need to pay attention to the text being comprehensive, trustworthy and persuasive to maximize effectiveness.

A Smartphone Intervention to Promote a Sustainable Healthy Diet: Protocol for a Pilot Study.

BACKGROUND: Changing current dietary patterns into sustainable healthy diets (ie, healthy diets with low environmental impact and socioeconomic fairness) is urgent. So far, few eating behavior change interventions have addressed all the dimensions of sustainable healthy diets at once and used cutting-edge methods from the field of digital health behavior change. OBJECTIVE: The primary objectives of this pilot study were to assess the feasibility and effectiveness of an individual behavior change intervention toward the adoption of a more environmentally sustainable healthy diet as a whole and changes in specific relevant food groups, food waste, and obtaining food from fair sources. The secondary objectives included the identification of mechanisms of action that potentially mediate the effect of the intervention on behaviors, identification of potential spillover effects and covariations among different food outcomes, and identification of the role of socioeconomic status in behavior changes. METHODS: We will run a series of ABA n-of-1 trials over a year, with the first A phase corresponding to a 2-week baseline evaluation, the B phase to a 22-week intervention, and the second A phase to a 24-week postintervention follow-up. We plan to enroll 21 participants from low, middle, and high socioeconomic statuses, with 7 from each socioeconomic group. The intervention will involve sending text messages and providing brief individualized web-based feedback sessions based on regular app-based assessments of eating behavior. The text messages will contain brief educational messages on human health and the environmental and socioeconomic effects of dietary choices; motivational messages to encourage the adoption of sustainable healthy diets by participants, providing tips to achieve their own behavioral goals; or links to recipes. Both quantitative and qualitative data will be collected. Quantitative data (eg, on eating behaviors and motivation) will be collected through self-reported questionnaires on several weekly bursts spread through the study. Qualitative data will be collected through 3 individual semistructured interviews before the intervention period, at the end of the intervention period, and at the end of the study. Analyses will be performed at both the individual and group levels depending on the outcome and objective. RESULTS: The first participants were recruited in October 2022. The final results are expected by October 2023. CONCLUSIONS: The results of this pilot study will be useful for designing future larger interventions on individual behavior change for sustainable healthy diets. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/41443.

Is the uptake, engagement, and effectiveness of exclusively mobile interventions for the promotion of weight-related behaviors equal for all? A systematic review.

Mobile health interventions are promising behavior change tools. However, there is a concern that they may benefit some populations less than others and thus widen inequalities in health. This systematic review investigated differences in uptake of, engagement with, and effectiveness of mobile interventions for weight-related behaviors (i.e., diet, physical activity, and sedentary behavior) based on a range of inequality indicators including age, gender, race/ethnicity, and socioeconomic status. The protocol was registered on PROSPERO (CRD42020192473). Six databases (CINAHL, EMBASE, ProQuest, PsycINFO, Pubmed, and Web of Science) were searched from inception to July 2021. Publications were eligible for inclusion if they reported the results of an exclusively mobile intervention and examined outcomes by at least one inequality indicator. Sixteen publications reporting on 13 studies were included with most reporting on multiple behaviors and inequality indicators. Uptake was investigated in one study with no differences reported by the inequality indicators studied. Studies investigating engagement (n = 7) reported differences by age (n = 1), gender (n = 3), ethnicity (n = 2), and education (n = 2), while those investigating effectiveness (n = 9) reported differences by age (n = 3), gender (n = 5), education (n = 2), occupation (n = 1), and geographical location (n = 1). Given the limited number of studies and their inconsistent findings, evidence of the presence of a digital divide in mobile interventions targeting weight-related behaviors is inconclusive. Therefore, we recommend that inequality indicators are specifically addressed, analyzed, and reported when evaluating mobile interventions.

Teaching open and reproducible scholarship: a critical review of the evidence base for current pedagogical methods and their outcomes.

In recent years, the scientific community has called for improvements in the credibility, robustness and reproducibility of research, characterized by increased interest and promotion of open and transparent research practices. While progress has been positive, there is a lack of consideration about how this approach can be embedded into undergraduate and postgraduate research training. Specifically, a critical overview of the literature which investigates how integrating open and reproducible science may influence student outcomes is needed. In this paper, we provide the first critical review of literature surrounding the integration of open and reproducible scholarship into teaching and learning and its associated outcomes in students. Our review highlighted how embedding open and reproducible scholarship appears to be associated with (i) students' scientific literacies (i.e. students' understanding of open research, consumption of science and the development of transferable skills); (ii) student engagement (i.e. motivation and engagement with learning, collaboration and engagement in open research) and (iii) students' attitudes towards science (i.e. trust in science and confidence in research findings). However, our review also identified a need for more robust and rigorous methods within pedagogical research, including more interventional and experimental evaluations of teaching practice. We discuss implications for teaching and learning scholarship.

Examining reactivity to the measurement of physical activity and sedentary behavior among women in midlife with elevated risk for cardiovascular disease.

OBJECTIVES: To estimate the extent of reactivity to measurement of physical activity (PA) and sedentary behavior among women in midlife with elevated risk for cardiovascular disease (CVD). DESIGN: Secondary analysis of a 10-day observational study of PA and sedentary behavior. MAIN OUTCOME MEASURES: PA (steps, minutes of light PA, total minutes of moderate-to- vigorous PA [MVPA]) and percent time in sedentary behavior per day were assessed using ActiGraph GT3X tri-axial accelerometers in 75 women in midlife with elevated CVD risk (e.g. hypertension; MAge = 51.61, MBMI = 34.02 kg/m2). Two-level multilevel models were used to test for evidence of reactivity, with the addition of random effects to test for evidence of individual differences in observed trends. RESULTS: All outcomes showed linear trends across days (ps < 0.001), though this masked what appeared to be meaningful dropoff after Day 1 or Day 2 (with little difference between subsequent days; srs ranging from 0.15 to 0.32). The random effect was significant only for percent time in sedentary behavior (χ2[1] = 10.40, p = 0.02). CONCLUSIONS: Consistent small to medium effects were found for all PA and sedentary behavior outcomes, underscoring the importance of considering measurement reactivity in populations with elevated CVD risk.

Pain experiences among women in midlife with existing health conditions: changes across pre-COVID-19, stay-at-home orders, and initial reopening.

OBJECTIVE: To examine the pain experiences of women in midlife with existing health conditions, including changes from prior to the COVID-19 pandemic through the first 6 months of the crisis. DESIGN: Women ages 40-60 with health conditions (e.g., hypertension; N = 35, MBMI = 32.2 kg/m2) were prompted to complete 5 surveys per day for 5 days at 3 time points: pre-COVID-19, during stay-at-home orders, and at initial reopening. MAIN OUTCOME MEASURES: Pain occurrence (yes/no), number of locations, and intensity. RESULTS: Women reported pain at 35% of surveys, particularly after waking and before bed compared to the middle of the day. The occurrence of pain decreased over time, whereas pain intensity decreased between pre-COVID-19 and stay-at-home orders but then remained stable. The number of pain locations decreased between stay-at-home orders and reopening, and pain was more variable during the pandemic than prior to its onset (srs = 0.24-0.32). CONCLUSION: Women experienced decreased pain frequency and intensity from prior to during the COVID-19 pandemic, though pain was less predictable during (vs. prior to) the pandemic. This information may be useful for informing care in this at-risk group, to prevent the development of chronic pain.

A systematic review and meta-analysis of studies of reactivity to digital in-the-moment measurement of health behaviour.

Self-report measures of health behaviour have several limitations including measurement reactivity, i.e., changes in people's behaviour, cognitions or emotions due to taking part in research. This systematic review investigates whether digital in-the-moment measures induce reactivity to a similar extent and why it occurs. Four databases were searched in December 2020. All observational or experimental studies investigating reactivity to digital in-the-moment measurement of a range of health behaviours were included if they were published in English in 2008 or later. Of the 11,723 records initially screened, 30 publications reporting on 31 studies were included in the qualitative synthesis/ 7 studies in the quantitative synthesis. Eighty-one percent of studies focused on reactivity to the measurement of physical activity indicators; small but meaningful pooled effects were found (Cohen's ds: 0.27-0.30). Only a small number of studies included other behaviours, yielding mixed results. Digital in-the-moment measurement of behaviour thus may be as prone to reactivity as self-reports in questionnaires. Measurement reactivity may be amplified by (1) ease of changing the behaviour (2) awareness of being measured and social desirability, and (3) resolving discrepancies between actual and desired behaviour through self-regulation.

Characteristics of smartphone-based dietary assessment tools: a systematic review.

Smartphones have become popular in assessing eating behaviour in real-life and real-time. This systematic review provides a comprehensive overview of smartphone-based dietary assessment tools, focusing on how dietary data is assessed and its completeness ensured. Seven databases from behavioural, social and computer science were searched in March 2020. All observational, experimental or intervention studies and study protocols using a smartphone-based assessment tool for dietary intake were included if they reported data collected by adults and were published in English. Out of 21,722 records initially screened, 117 publications using 129 tools were included. Five core assessment features were identified: photo-based assessment (48.8% of tools), assessed serving/ portion sizes (48.8%), free-text descriptions of food intake (42.6%), food databases (30.2%), and classification systems (27.9%). On average, a tool used two features. The majority of studies did not implement any features to improve completeness of the records. This review provides a comprehensive overview and framework of smartphone-based dietary assessment tools to help researchers identify suitable assessment tools for their studies. Future research needs to address the potential impact of specific dietary assessment methods on data quality and participants' willingness to record their behaviour to ultimately improve the quality of smartphone-based dietary assessment for health research.