Development of Momentary Appetite Capture (MAC): A versatile tool for monitoring appetite over long periods.

Understanding how an intervention impacts appetite in real-life settings and over several days remains a challenging and under-explored research question. To this end, we developed Momentary Appetite Capture (MAC), a form of ecological momentary assessment that combines automated text messaging with an online platform. Participants report their appetite using visual analogue scales (hunger, desire to eat, and fullness) and a virtual portion-size selection task. In two separate studies, we assessed the feasibility and test-retest reliability of MAC. Participants were prompted every 2 hours over a 14-hour window, and they repeated this assessment over two consecutive weekdays. For each participant, we calculated a daily time-averaged area under the curve (AUC) for each appetite measure. In Study One (N = 25) time-averaged AUC was significantly positively correlated across test days for hunger (r = 0.563, p = .003), desire to eat (r = 0.515, p = .008) and prospective portion size (r = 0.914, p < .001), but not for fullness (r = 0.342, p = .094). Participants completed 95% of MACs (380 of 400), and we used participant feedback to improve the MAC tool and study protocol for Study Two. In Study Two (N = 31), 94% of MACs were completed (468 of 496). Across days, time-averaged AUC was significantly positively correlated for hunger (r = 0.595, p = < .001), fullness (r = 0.501, p = .004), desire to eat (r = 0.585, p < .001), and prospective portion size (r = 0.757, p < .001). Together, these studies suggest that MAC could be an acceptable and reliable tool to track appetite throughout the day. In the future, MAC could be used to explore the impact of weight-loss interventions on natural fluctuations in appetite.

Exploring the acute effects of running on cerebral blood flow and food cue reactivity in healthy young men using functional magnetic resonance imaging.

Acute exercise suppresses appetite and alters food-cue reactivity, but the extent exercise-induced changes in cerebral blood flow (CBF) influences the blood-oxygen-level-dependent (BOLD) signal during appetite-related paradigms is not known. This study examined the impact of acute running on visual food-cue reactivity and explored whether such responses are influenced by CBF variability. In a randomised crossover design, 23 men (mean ± SD: 24 ± 4 years, 22.9 ± 2.1 kg/m2 ) completed fMRI scans before and after 60 min of running (68% ± 3% peak oxygen uptake) or rest (control). Five-minute pseudo-continuous arterial spin labelling fMRI scans were conducted for CBF assessment before and at four consecutive repeat acquisitions after exercise/rest. BOLD-fMRI was acquired during a food-cue reactivity task before and 28 min after exercise/rest. Food-cue reactivity analysis was performed with and without CBF adjustment. Subjective appetite ratings were assessed before, during and after exercise/rest. Exercise CBF was higher in grey matter, the posterior insula and in the region of the amygdala/hippocampus, and lower in the medial orbitofrontal cortex and dorsal striatum than control (main effect trial p ≤ .018). No time-by-trial interactions for CBF were identified (p ≥ .087). Exercise induced moderate-to-large reductions in subjective appetite ratings (Cohen's d = 0.53-0.84; p ≤ .024) and increased food-cue reactivity in the paracingulate gyrus, hippocampus, precuneous cortex, frontal pole and posterior cingulate gyrus. Accounting for CBF variability did not markedly alter detection of exercise-induced BOLD signal changes. Acute running evoked overall changes in CBF that were not time dependent and increased food-cue reactivity in regions implicated in attention, anticipation of reward, and episodic memory independent of CBF.

Evaluating the benefit of early patient and public involvement for product development and testing with small companies.

INTRODUCTION: There is a growing understanding of the benefits of patient and public involvement (PPI), and its evaluation, in research. An online version of the CUBE PPI evaluation framework has been developed. We sought to use the CUBE to evaluate the value of early PPI with two small healthcare companies during product development. METHODS: Contributors were recruited online and had lived experience of either type 1 diabetes or obesity. Two 1-h sessions were run with a company developing a smartphone application to manage diabetes (DEE-EM): one with young people (YP; n = 5) and one with parents (n = 7). Two 1-h sessions were run with a company developing a weight-loss product, both with adults (n = 7 in each session). Sessions were facilitated by an independent University researcher and attended by company representatives, who presented their product. One facilitator led the evaluation of the session by giving a demonstration of the CUBE and asking simple questions in the YP session. RESULTS: A high proportion of contributors completed the CUBE (80.5% DEE-EM; 93% Oxford Medical Products). Responses were positive to all four CUBE dimensions (in italics). Contributors felt there were diverse ways to contribute to the sessions, and that they had a strong voice to add to the discussion. Balance was achieved regarding whose concerns (public or company) led the agenda, and contributors felt that both companies would make changes based on the discussion. The supportive attitude of both companies resulted in most contributors feeling comfortable participating in PPI sessions with the industry, while recognising the profit-making aspect of their work. CONCLUSIONS: PPI with small healthcare companies is both feasible and worthwhile. The CUBE framework facilitated the evaluation of the interaction between experts in different knowledge spaces. We provide recommendations for future projects, including considerations of who should participate and the level of implicit endorsement of the product that participation implies. PATIENT OR PUBLIC CONTRIBUTION: People with lived experience of type 1 diabetes or obesity were invited to contribute to one of four PPI sessions, which they then evaluated. One contributor agreed to contribute to the analysis of the evaluation data and interpretation and preparation of the manuscript.

Snacking and anxiety during the coronavirus disease (COVID-19) pandemic: A prospective cohort study.

Anxiety and snacking increased during the initial coronavirus disease 2019 (COVID-19) lockdowns, but it remains unknown whether this change in snacking persisted and if it related to anxiety levels. We used prospective data to examine changes in snacking frequency from t1 (eased restrictions in England in May-June 2020) to t2 (national lockdown in December 2020-March 2021), the association of anxiety (assessed by the Generalised Anxiety Disorder-7 questionnaire at t1) with the snacking change, and the mediating and moderating effects of disinhibition and flexible restraint (assessed by the Three Factor Eating Questionnaire in 2016-17). Analyses including 2128 adults (mean age 28.4 y) residing in England from the Avon Longitudinal Study of Parents and Children showed that snacking frequency increased over time (mean change 1.23 (95% CI 0.81, 1.65) snacks/wk). Linear regressions of snacking adjusted for sociodemographic covariates showed that having clinical levels of generalised anxiety at t1, versus not, was associated with 1.22 (95% CI 0.07, 2.37) more snacks/wk at t2. Disinhibition partially mediated the association between Generalised Anxiety Disorder and snacking (ßindirect = 0.15, 95% CI 0.01, 0.32), while there was no evidence that flexible restraint moderated the association (ß = 0.05, 95% CI -0.57, 0.66). Our longitudinal findings highlight a detrimental anxiety-snacking association partly operating via disinhibition, suggesting future research could target mitigating anxiety and disinhibited eating behaviours to benefit diet-related outcomes following the pandemic.

Integrating COM-B and the person-based approach to develop an ACT based therapy programme to raise self-determination in adolescents with obesity.

BACKGROUND: This paper details the development of the Adolescent Intrinsic Motivation 'AIM2Change' intervention to support weight-management in young people previously unable to make changes whilst attending a tier 3 weight management service for children and young people. AIM2Change is an acceptance and commitment therapy based intervention that will be delivered one-to-one online over a seven-week period. METHODS: To develop this intervention, we have triangulated results from a qualitative research study, patient and public involvement groups (PPI) and a COM-B (capability, opportunity, motivation, behaviour) analysis, in a method informed by the person-based approach. RESULTS: The integrated development approach yielded a broad range of perspectives and facilitated the creation of a tailored intervention to meet the needs of the patient group whist remaining pragmatic and deliverable. CONCLUSIONS: The next steps for this intervention will be in-depth co-development of the therapy sessions with service users, before implementing a proof of concept trial.

The feasibility, acceptability, and benefit of interventions that target eating speed in the clinical treatment of children and adolescents with overweight or obesity: A systematic review and meta-analysis.

Eating at a faster speed is positively correlated with having a higher BMI. Modifying eating speed may offer a treatment opportunity for those with overweight and obesity. This review sought to understand the feasibility, acceptability, and benefit to using eating speed interventions in paediatric clinical weight-management settings. The PICO Framework was used. Clinical studies of eating speed interventions as a treatment for paediatric patients with overweight or obesity were included. No limits to search date were implemented. A systematic search of MEDLINE, PsychINFO and EMBASE via OVID, Web of Science and JBI, Database of systematic reviews and Implementation reports, along with trial registers NICE, ClinicalTrials.gov and Cochrane Central Register of Controlled Trials was conducted. Two authors were responsible for screening, extraction, and evaluation of the risk of bias. Fifteen papers reporting twelve interventions addressing eating-speed were identified, involving a total of 486 active participants (range 7-297). Study design was weak with only one full RCT and there were some concerns over quality and risk of bias (Cochrane RoB 2.0). Limited sample sizes and different measured outcomes did not allow powered evaluations of effect for all outcomes. There is some indication, overall, that addressing eating speed has the potential to be a beneficial adjunct to clinical obesity treatment, although the pooled effect estimate did not demonstrate a difference in BMISDS status following eating speed interventions compared to control [pooled mean difference (0.04, 95% CI -0.39 to 0.46, N = 3)]. Developments to improve the engagement to, and acceptability of, interventions are required, alongside rigorous high-quality trials to evaluate effectiveness.

How full am I? The effect of rating fullness during eating on food intake, eating speed and relationship with satiety responsiveness.

Modifying eating behaviours may be an effective strategy to limit excess food intake, such as eating slower and mindfully. We hypothesized that regularly rating fullness whilst eating a standard meal in one course would increase post-meal satiety and reduce intake in a subsequent course during the same sitting. A between-subjects design was employed (n = 65; 75% female; mean age = 26.7 (s.d. = 9.5); mean body mass index = 22.4 (s.d. = 3.3)), with three conditions of within-meal visual-analogue-scale ratings: 'Fullness' (rated fullness); 'Taste' (rated pleasantness of taste of food); 'Control' (rated comfort of room). Fasted participants ate a pasta meal (327 kcal) followed by cookies ad libitum. Appetite ratings were measured at baseline, following each course and for 3-h post-meal. Satiety responsiveness was measured using the Adult Eating Behaviour Questionnaire, Intuitive Eating Scale and by calculating the satiety quotient of the pasta course alone and the whole meal. The primary outcomes were fullness ratings post-pasta course [mean (s.d.): Fullness = 67.1 (21.9); Taste = 64.4 (13.7); Control = 60.2 (21.5)] and cookie intake [mean kcal (s.d.): Fullness = 249 (236); Taste = 279 (231); Control = 255 (208)]. Eating speed was included as a secondary, control outcome [mean (s.d.): Fullness = 59.3 (9.0); Taste = 59.2 (17.7); Control = 60.7 (19.6)]. No evidence for a difference in outcomes was identified between conditions (p > 0.05). Future work could involve testing the impact of rating fullness during multiple meals over a longer period. Secondly, this study explored whether levels of satiety responsiveness influenced the impact of the manipulation on outcomes; however only weak evidence for a relationship with eating speed was found. Finally, only a weak relationship was found between the satiety responsiveness measures, suggesting that different aspects of the underlying construct are being captured.

When do children learn how to select a portion size?

The reduction of portion sizes supports weight-loss. This study looks at whether children have a conceptual understanding of portion size, by studying their ability to manually serve a portion size that corresponds to what they eat. In a clinical setting, discussion around portion size is subjective thus a computerised portion size tool is also trialled, with the portion sizes chosen on the screen being compared to amounts served manually. Children (n = 76) age 5-6, 7-8 and 10-11 were asked to rate their hunger (VAS scale), liking (VAS scale) and 'ideal portion size for lunch' of eight interactive meal images using a computerised portion size tool. Children then manually self-served and consumed a portion of pasta. Plates were weighed to allow for the calculation of calories served and eaten. A positive correlation was found between manually served food portions and the amount eaten (r = 0.53, 95%CI [0.34, 0.82, P < .001), indicating that many children were able to anticipate their likely food intake prior to meal onset. A regression model demonstrates that age contributes to 9.4% of the variance in portion size accuracy (t(68) = -2.3, p = .02). There was no relationship between portion size and either hunger or liking. The portion sizes chosen on the computer at lunchtime correlated to the amount manually served overall (r = .34, 95%CI [0.07, 0.55], p < .01), but not in 5-6-year-old children. Manual portion-size selection can be observed in five-year olds and from age seven, children's 'virtual' responses correlate with their manual portion selections. The application of the computerised portion-size tool requires further development but offers considerable potential.

Using neuroimaging to investigate the impact of Mandolean® training in young people with obesity: a pilot randomised controlled trial.

BACKGROUND: Slowing eating rate using the Mandolean® previously helped obese adolescents to self-select smaller portion sizes, with no reduction in satiety, and enhanced ghrelin suppression. The objective of this pilot, randomised trial was to investigate the neural response to food cues following Mandolean® training using functional Magnetic Resonance Imaging (fMRI), and measures of ghrelin, PYY, glucose and self-reported appetite. METHOD: Twenty-four obese adolescents (11-18 years; BMI ≥ 95th centile) were randomised (but stratified by age and gender) to receive six-months of standard care in an obesity clinic, or standard care plus short-term Mandolean® training. Two fMRI sessions were conducted: at baseline and post-intervention. These sessions were structured as an oral glucose tolerance test, with food cue-reactivity fMRI, cannulation for blood samples, and appetite ratings taken at baseline, 30 (no fMRI), 60 and 90 min post-glucose. As this was a pilot trial, a conservative approach to the statistical analysis of the behavioural data used Cliff's delta as a non-parametric measure of effect size between groups. fMRI data was analysed using non-parametric permutation analysis (RANDOMISE, FSL). RESULTS: Following Mandolean® training: (i) relatively less activation was seen in brain regions associated with food cue reactivity after glucose consumption compared to standard care group; (ii) 22% reduction in self-selected portion size was found with no reduction in post-meal satiety. However, usage of the Mandolean® by the young people involved was variable and considerably less than planned at the outset (on average, 28 meals with the Mandolean® over six-months). CONCLUSION: This pilot trial provides preliminary evidence that Mandolean® training may be associated with changes in how food cues in the environment are processed, supporting previous studies showing a reduction in portion size with no reduction in satiety. In this regard, the study supports targeting eating behaviour in weight-management interventions in young people. However, given the variable usage of the Mandolean® during the trial, further work is required to design more engaging interventions reducing eating speed. TRIAL REGISTRATION: ISRCTN, ISRCTN84202126 , retrospectively registered 22/02/2018.

Almost winning: induced MEG theta power in insula and orbitofrontal cortex increases during gambling near-misses and is associated with BOLD signal and gambling severity.

In slot machine gambling, the "near-miss effect" (when a losing display physically resembles an actual win display) has been implicated in pathological gambling (PG). Functional magnetic resonance imaging (fMRI) with PG and non-PG participants shows that near-misses recruit reward-related circuitry, but little is known about the temporal dynamics and oscillatory changes underlying near-misses. The present multi-modal imaging study investigated the near-miss effect by combining the spatial resolution of blood oxygen-level dependent (BOLD)-fMRI with the spatial and temporal resolution of magnetoencephalography (MEG) during a slot machine task in PG and non-PG groups. Given previous findings on outcome (win and near-miss) processing, functional overlap was hypothesized between induced changes in temporal oscillations and BOLD response to wins and near-misses in PG. We first validated our task in a sample of varying gambling severity using BOLD-fMRI and then compared PG and non-PG participants using MEG to investigate changes in induced oscillatory power associated with win and near-miss, relative to loss, outcomes. Across both modalities, near-misses recruited similar brain regions to wins, including right inferior frontal gyrus and insula. Using MEG, increased theta-band (4-7Hz) oscillations to near-misses were observed in the insula and right orbitofrontal cortex (OFC). Furthermore, this theta-band activity was positively associated with gambling severity. These findings demonstrate that the near-miss effect in insula and OFC is associated with induced theta oscillations. The significance of these findings for theories of PG and the development of potential biomarkers and therapeutic targets is discussed.

Associations between body mass index and episodic memory for recent eating, mindful eating, and cognitive distraction: A cross-sectional study.

Objectives: Eating while distracted has been associated with a higher body mass index (BMI), whereas mindful eating and episodic memory for recent eating have shown the opposite pattern. This pre-registered, global study (https://osf.io/rdjzk) compared the relative association between these variables (and four "positive controls": restraint, disinhibition, emotional eating, plate clearing) and self-reported BMI. The timing of data collection (April-May 2020) during the SARS-CoV-2 pandemic enabled an investigation of the impact of stay-at-home restrictions imposed on the UK population on the measures of eating behavior. Methods: An online survey was completed, including: (i) demographic data (e.g., self-reported BMI), (ii) Likert ratings assessing episodic memory for recent eating, mindful eating, cognitive distraction, restrained eating, emotional eating, disinhibition and plate clearing over the last 12 months and the last 7 days (during the first UK COVID-19 lockdown), and (iii) the Mindful Eating Questionnaire (MEQ). Results: A large adult sample participated (N = 846; mean (SD) age = 33.0 (14.3) years; mean (SD) BMI = 24.6 (5.6) kg/m2). Mindful eating (MEQ-total score) was associated with a lower self-reported BMI (ß = -0.12; 95% CI = -0.20, -0.04; p = 0.004), whereas disinhibited eating was associated with a higher self-reported BMI (ß = 0.30; 95% CI = 0.21, 0.38; p < 0.001). In UK participants (n = 520), consistent changes in eating behavior during lockdown were not found. For those that did experience change, decreases were reported in; emotional eating, disinhibited eating, focusing on taste during a meal (a measure of mindful eating), and using a smart phone while eating. Conclusions: These findings provide evidence in a large global sample for associations between BMI and (i) mindful eating, and (ii) disinhibited eating. Future research should evaluate whether mindful eating demonstrates a prospective association with body weight and should consider mechanisms of action.

Daily Duration of Eating for Children and Adolescents: A Systematic Review and Meta-Analysis.

Time-limited eating is a dietary intervention whereby eating is limited to a specific window of time during the day. The usual eating windows of adults, and how these can be manipulated for dietary interventions, is well documented. However, there is a paucity of data on eating windows of young people, the manipulation of which may be a useful intervention for reducing obesity. This paper reviewed the existing literature on the eating windows of children and adolescents, aged 5-18 years, plus clock times of first and last intakes and variations by subgroup. Two databases (Medline and Embase) were searched for eligible papers published between February 2013 and February 2023, with forward searching of the citation network of included studies on Web of Science. Articles were screened, and data extracted, in duplicate by two independent reviewers. Ten studies were included, with both observational and experimental designs. Narrative synthesis showed large variations in eating windows with average values ranging from 9.7 h to 16.4 h. Meta-analysis, of five studies, showed a pooled mean daily eating window of 11.3 h (95% CI 11.0, 11.7). Large variations in eating windows exist across different study populations; however, the pooled data suggest that it may be possible to design time-limited eating interventions in paediatric populations aimed at reducing eating windows. Further high-quality research, investigating eating windows and subsequent associations with health outcomes, is needed.

Evaluating Eating Behaviour, Energy Homeostasis, and Obesity in Childhood-Onset Craniopharyngioma: A Feasibility Study.

INTRODUCTION: Craniopharyngiomas are rare brain tumours (incidence 1.1-1.7 cases/million/year). Although non-malignant, craniopharyngioma causes major endocrine and visual morbidities including hypothalamic obesity, yet mechanisms leading to obesity are poorly understood. This study investigated the feasibility and acceptability of eating behaviour measures in patients with craniopharyngioma to inform the design of future trials. METHODS: Patients with childhood-onset craniopharyngioma and controls matched for sex, pubertal stage, and age were recruited. After an overnight fast, participants received the following measures: body composition, resting metabolic rate, oral glucose tolerance test including magnetic resonance imaging (patients only), appetite ratings, eating behaviour, and quality of life questionnaires, ad libitum lunch, and an acceptability questionnaire. Data are reported as median ± IQR, with effect size measure (Cliff's delta) and Kendall's tau for correlations, due to the small sample size. RESULTS: Eleven patients (median age = 14 years; 5 F/6 M) and matched controls (median age = 12 years; 5 F/6 M) were recruited. All patients had received surgery, and 9/11 also received radiotherapy. Hypothalamic damage post-surgery was graded (Paris grading): grade 2 n = 6; grade 1 n = 1; grade 0 n = 2. The included measures were deemed highly tolerable by participants and their parent/carers. Preliminary data suggest a difference in hyperphagia between patients and controls (d = 0.5), and a relationship between hyperphagia with body mass index standard deviation score (BMISDS) in patients (τ = 0.46). DISCUSSION: These findings demonstrate that eating behaviour research is feasible and acceptable to craniopharyngioma patients and there is an association between BMISDS and hyperphagia in patients. Thus, food approach and avoidance behaviours may be useful targets for interventions to manage obesity in this patient group.

The 'variety effect' is anticipated in meal planning.

The 'variety effect' describes the greater consumption that is observed when multiple foods with different sensory characteristics are presented either simultaneously or sequentially. Variety increases the amount of food consumed in test of ad libitum intake. However, outside the laboratory, meals are often planned in advance and then consumed in their entirety. We sought to explore the extent to which the variety effect is anticipated in this pre-meal planning. Participants were shown two food images, each representing a first or a second course of a hypothetical meal. The two courses were either, (i) exactly the same food, (ii) different foods from the same sensory category (sweet or savoury), or (iii) different foods from a different sensory category. In Study 1 (N=30) these courses comprised typical 'main meal' foods and in Study 2 (N=30) they comprised snack foods. For each pair of images, participants rated their expected liking of the second course and selected ideal portion sizes, both for the second course and the first and second course, combined. In both studies, as the difference between the courses (from (i) same to (ii) similar to (iii) different) increased, the second course was selected in a larger portion and it was rated as more pleasant. To our knowledge, these are the first studies to show that the variety effect is evident in the energy content of self-selected meals. This work shows that effects of variety are learned and anticipated. This extends our characterisation beyond a passive process that develops towards the end of a meal.

Using photography in 'The Restaurant of the Future'. A useful way to assess portion selection and plate cleaning?

Laboratory-based studies of human dietary behaviour benefit from highly controlled conditions; however, this approach can lack ecological validity. Identifying a reliable method to capture and quantify natural dietary behaviours represents an important challenge for researchers. In this study, we scrutinised cafeteria-style meals in the 'Restaurant of the Future.' Self-selected meals were weighed and photographed, both before and after consumption. Using standard portions of the same foods, these images were independently coded to produce accurate and reliable estimates of (i) initial self-served portions, and (ii) food remaining at the end of the meal. Plate cleaning was extremely common; in 86% of meals at least 90% of self-selected calories were consumed. Males ate a greater proportion of their self-selected meals than did females. Finally, when participants visited the restaurant more than once, the correspondence between selected portions was better predicted by the weight of the meal than by its energy content. These findings illustrate the potential benefits of meal photography in this context. However, they also highlight significant limitations, in particular, the need to exclude large amounts of data when one food obscures another.

An App-Based Intervention for Pediatric Weight Management: Pre-Post Acceptability and Feasibility Trial.

BACKGROUND: A multidisciplinary approach to weight management is offered at tier 3 pediatric weight management services in the United Kingdom. Encouraging dietary change is a major aim, with patients meeting with dieticians, endocrinologists, psychologists, nurse specialists, and social workers on average every other month. OBJECTIVE: This research sought to trial an inhibitory control training smartphone app-FoodT-with the clinic population of a pediatric weight management service. FoodT has shown positive impacts on food choice in adult users, with resulting weight loss. It was hoped that when delivered as an adjunctive treatment alongside the extensive social, medical, psychological, and dietetic interventions already offered at the clinic, the introduction of inhibitory control training may offer patients another tool that supports eating choice. In this feasibility trial, recruitment, retention, and app use were the primary outcomes. An extensive battery of measures was included to test the feasibility and acceptability of these measures for future powered trials. METHODS: FoodT was offered to pediatric patients and their parents during a routine clinic appointment, and patients were asked to use the app at home every day for the first week and once per week for the rest of the month. Feasibility and acceptability were measured in terms of recruitment, engagement with the app, and retention to the trial. A battery of psychometric tests was given before and after app use to assess the acceptability of collecting data on changes to food choices and experiences that would inform future trial work. RESULTS: A total of 12 children and 10 parents consented (22/62, 35% of those approached). Further, 1 child and no parents achieved the recommended training schedule. No participants completed the posttrial measures. The reasons for not wanting to be recruited to the trial included participants not considering their weight to be connected to eating choices and not feeling that the app suited their needs. No reasons are known for noncompletion. CONCLUSIONS: It is unclear whether the intervention itself or the research processes, including the battery of measures, prevented completion. It is therefore difficult to make any decisions as to the value that the app has within this setting. Important lessons have been learned from this research that have potential broad relevance, including the importance of co-designing interventions with service users and avoiding deterring people from early-stage participation in extensive data collection.

The influence of physical activity on neural responses to visual food cues in humans: A systematic review of functional magnetic resonance imaging studies.

This systematic review examined whether neural responses to visual food-cues measured by functional magnetic resonance imaging (fMRI) are influenced by physical activity. Seven databases were searched up to February 2023 for human studies evaluating visual food-cue reactivity using fMRI alongside an assessment of habitual physical activity or structured exercise exposure. Eight studies (1 exercise training, 4 acute crossover, 3 cross-sectional) were included in a qualitative synthesis. Structured acute and chronic exercise appear to lower food-cue reactivity in several brain regions, including the insula, hippocampus, orbitofrontal cortex (OFC), postcentral gyrus and putamen, particularly when viewing high-energy-density food cues. Exercise, at least acutely, may enhance appeal of low-energy-density food-cues. Cross-sectional studies show higher self-reported physical activity is associated with lower reactivity to food-cues particularly of high-energy-density in the insula, OFC, postcentral gyrus and precuneus. This review shows that physical activity may influence brain food-cue reactivity in motivational, emotional, and reward-related processing regions, possibly indicative of a hedonic appetite-suppressing effect. Conclusions should be drawn cautiously given considerable methodological variability exists across limited evidence.

The Effect of Intermittent Fasting on Appetite: A Systematic Review and Meta-Analysis.

Previously, narrative reviews have considered the effects of intermittent fasting on appetite. One suggestion is that intermittent fasting attenuates an increase in appetite that typically accompanies weight loss. Here, we conducted the first systematic review and meta-analysis to quantify the effects of intermittent fasting on appetite, when compared to a continuous energy restriction intervention. Five electronic databases and trial registers were searched in February 2021 and February 2022. Abstracts (N = 2800) were screened and 17 randomized controlled trials (RCTs), consisting of a variety of intermittent fasting regimes, met our inclusion criteria. The total number of participants allocated to interventions was 1111 and all RCTs were judged as having either some concerns or a high risk of bias (Cochrane RoB 2.0 tool). Random effects meta-analyses were conducted on change-from-baseline appetite ratings. There was no clear evidence that intermittent fasting affected hunger (WMD = -3.03; 95% CI [-8.13, 2.08]; p = 0.25; N = 13), fullness (WMD = 3.11; 95% CI [-1.46, 7.69]; p = 0.18; N = 10), desire to eat (WMD = -3.89; 95% CI [-12.62, 4.83]; p = 0.38; N = 6), or prospective food consumption (WMD = -2.82; 95% CI [-3.87, 9.03]; p = 0.43; N = 5), differently to continuous energy restriction interventions. Our results suggest that intermittent fasting does not mitigate an increase in our drive to eat that is often associated with continuous energy restriction.

Nucleus accumbens response to food cues predicts subsequent snack consumption in women and increased body mass index in those with reduced self-control.

Individuals have difficulty controlling their food consumption, which is due in part to the ubiquity of tempting food cues in the environment. Individual differences in the propensity to attribute incentive (motivational) salience to and act on these cues may explain why some individuals eat more than others. Using fMRI in healthy women, we found that food cue related activity in the nucleus accumbens, a key brain region for food motivation and reward, was related to subsequent snack food consumption. However, both nucleus accumbens activation and snack food consumption were unrelated to self-reported hunger, or explicit wanting and liking for the snack. In contrast, food cue reactivity in the ventromedial prefrontal cortex was associated with subjective hunger/appetite, but not with consumption. Whilst the food cue reactivity in the nucleus accumbens that predicted snack consumption was not directly related to body mass index (BMI), it was associated with increased BMI in individuals reporting low self-control. Our findings reveal a neural substrate underpinning automatic environmental influences on consumption in humans and demonstrate how self-control interacts with this response to predict BMI. Our data provide support for theoretical models that advocate a 'dual hit' of increased incentive salience attribution to food cues and poor self-control in determining vulnerability to overeating and overweight.

Computer-based assessments of expected satiety predict behavioural measures of portion-size selection and food intake.

Previously, expected satiety (ES) has been measured using software and two-dimensional pictures presented on a computer screen. In this context, ES is an excellent predictor of self-selected portions, when quantified using similar images and similar software. In the present study we sought to establish the veracity of ES as a predictor of behaviours associated with real foods. Participants (N=30) used computer software to assess their ES and ideal portion of three familiar foods. A real bowl of one food (pasta and sauce) was then presented and participants self-selected an ideal portion size. They then consumed the portion ad libitum. Additional measures of appetite, expected and actual liking, novelty, and reward, were also taken. Importantly, our screen-based measures of expected satiety and ideal portion size were both significantly related to intake (p<.05). By contrast, measures of liking were relatively poor predictors (p>.05). In addition, consistent with previous studies, the majority (90%) of participants engaged in plate cleaning. Of these, 29.6% consumed more when prompted by the experimenter. Together, these findings further validate the use of screen-based measures to explore determinants of portion-size selection and energy intake in humans.