BACKGROUND:Weight loss maintenance (WLM) remains a limitation of behavioral obesity interventions, as long-term adherence is burdensome and diminishes over time. Simplified recommendations and/or alternative delivery methods that target evidence-based WLM strategies may reduce burden to improve long-term outcomes. METHODS:This protocol describes a multiphase optimization strategy (MOST) trial using a 2x2x2x2 factorial design to optimize a 12-month extended care program for weight loss maintenance. Adults with obesity who achieve at least 5% weight loss during an initial 4-month behavioral weight loss program are randomized to receive a core maintenance program plus zero to four "minimally disruptive" intervention components: reduced food variety, home-based resistance training, buddy training and support, and acceptance and commitment therapy workshops. RESULTS:The primary outcome is weight loss maintenance at 12 months following randomization. Secondary outcomes include treatment adherence, treatment burden, behavioral maintenance constructs, and hypothesized mediators and moderators of intervention effects. DISCUSSION:This study explores unconventional but evidence-based treatment strategies for WLM and applies a 'minimally disruptive medicine' paradigm to behavioral maintenance. These findings have the potential to inform best practices for the provision of WLM interventions, improve long-term outcomes for individuals accessing weight management services, and strengthen the overall public health impact of available interventions for disease prevention and management. TRIAL REGISTRATION:NCT, NCT06785064. Registered [01/15/2025], https://clinicaltrials.gov/study/NCT06785064?term=NCT06785064&rank=1.

Introduction:Physical activity (PA) is known to mitigate risk for cardiovascular disease (CVD) and improve overall well-being, though many women do not meet national PA guidelines. Menstrual-related symptoms and related biopsychosocial fluctuations may be a key, but often overlooked, determinant of daily PA behavior. Traditional methods of assessment are limited in their ability to capture such dynamic experiences within-person. Methods:Using a 45-day intensive assessment protocol, Project PACE is designed to overcome the limitations of existing approaches, to examine temporal associations between menstrual symptoms, PA, and related experiences (e.g. sleep) among insufficiently active women with at least one CVD risk marker. Participants (N = 60) will self-report menstrual symptoms, PA, PA-related cognitions, and other daily health behaviors twice per day via electronic surveys, and wear a Fitbit Inspire device for continuous assessment of PA and sleep. Primary analyses will use multilevel models to examine within-person associations between daily menstrual cycle symptoms and PA behavior, while exploratory analyses will examine potential mechanisms and sources of heterogeneity in these associations. Results:We hypothesize that (1) PA behavior, menstrual experiences, and cognitive PA determinants (e.g. motivation, intentions, self-efficacy) will be highly variable within-person, reflecting low stability across days, and (2) on days when participants experience more intense symptoms relative to their typical levels, they will report lower motivation, intentions, and self-efficacy for PA. Discussion:The goal of this study is to clarify these associations among women ages 18-50. This information will be useful for informing improvements to personalized and adaptive PA interventions for women.

OBJECTIVES:To estimate the extent of physical activity (PA) measurement reactivity among adults ages 40-60 with risk factors for cardiovascular disease (CVD), to inform best practices for addressing reactivity in PA research and intervention. DESIGN:Coordinated secondary analysis across six datasets from studies that used 6-7 days of observation following the introduction of PA measurement devices. Moderators of interest were demographic and study design characteristics. METHODS:We included data from participants ages 40-60 with ≥1 CVD factors who provided device-assessed PA behaviour across 6-7 days (N = 1825). We used multilevel modelling to examine participants' PA behaviour (i.e., activity units, steps per day) across days, with decreases in activity indicating reactivity. The threshold for statistical significance was set at p < .05 and standardized effect sizes of interest were semipartial correlation coefficients (srs) ≥.25; we also report conversions to Cohen's d and corresponding equivalence tests. RESULTS:No patterns met both criteria for significance for either main or moderation effects, including tests of study design features. Results from one small study showed a decrease in steps per day across days of observation (p = .15, sr = .26, d = .23, 90% CI: -.03, .50), though men showed an increase in steps per day (whereas women decreased). CONCLUSIONS:Adults in midlife with CVD risk factors show little evidence of PA measurement reactivity. We recommend continuing to examine PA patterns in individual studies, though widespread use of burdensome procedures to prevent reactivity is not warranted in this at-risk population.

OBJECTIVE:Weight loss requires constant effortful decision-making. Following a more routine (vs. varied) diet may allow healthy choices to become more habitual, that is, automatic. The current study examined whether routinized eating patterns predicted success for 112 participants in a behavioral weight loss program. METHOD:Using daily food logs from the first 12 weeks of the program, we examined whether caloric stability (daily calorie fluctuations and weekday-weekend fluctuations) and dietary repetition (percentage of unique foods tracked and percentage of foods logged 10+ times) predicted 12-week weight loss. RESULTS:Greater dietary repetition (both metrics) and more daily calorie stability were associated with higher weight loss. However, contrary to hypotheses, participants with higher weekend-weekday deviations also had greater weight loss. CONCLUSION:Overall, findings suggest that more routinized eating patterns during a weight loss attempt may facilitate success. Future work should confirm these findings with experimental manipulations and identify potential mechanisms of action. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Background Approximately 2 billion adults seek lifestyle modification to improve their health and well-being. However, because of cost and access barriers, only a tiny fraction receive gold-standard lifestyle modification programs led by trained coaches. Digital programs without human coaches are more disseminable but have limited efficacy. Recent advances in large language model (LLM) AI chatbots have the potential to revolutionize digital programs by emulating human coaches, offering a safe, low-cost, and scalable lifestyle modification intervention. Yet, no studies have developed and tested such a program.Purpose This study aims to evaluate the feasibility, safety, and user engagement of a new AI chatbot-powered lifestyle modification program named Lyra, which utilizes recent advances in LLM technology to potentially emulate the benefits of human coaching.Methods We developed Lyra, which integrates structured psychoeducational programming, digital tracking of health behaviors, and text messaging, all powered by an LLM engine. We tested the 8-week program, which included interactive training in behavioral strategies, customized meal plans, tailored feedback on goal progress, and on-demand coaching, with 17 participants in a sample of participants with overweight/obesity seeking lifestyle modification.Results The program was successfully implemented at a cost of $1.78/participant/week. Coders rated 2288 messages from and 475 conversations with Lyra. All were deemed safe, and the mean expertise was 8.5/10. Participants (mean BMI = 31.5) rated Lyra as helpful (69%), empathic (88%), and easy to use (94%); 88% valued having 24-h availability, and 75% developed a connection to Lyra. Participants initiated an average of 6.2 conversations, ranging from coping with cravings to unprompted "confessions" of having consumed unhealthy food.Conclusion This new form of intervention proved feasible, acceptable, safe, clinically adept, and capable of fostering a connection. However, rigorous testing of Lyra's effectiveness is necessary. Billions of people around the world seek to improve their diet and exercise habits ("lifestyle modification" or lifestyle modification) in order to gain better health and quality of life. However, these changes are extremely hard to make, and existing digital programs are not effective. This study used newly available artificial intelligence (AI) to power a chatbot-based lifestyle modification program. The program, called Lyra, delivered lifestyle modification through text messages and incorporated features like goal setting, meal planning, and personalized advice based on digitally tracked physical activity, dietary, and weight data. Results from the study showed that most of the 17 participants found Lyra easy to use, engaging, and helpful in managing their lifestyle goals. They appreciated Lyra's availability for support at any time, which traditional programs often lack. Additionally, participants felt a surprisingly strong connection to Lyra, highlighting the chatbot's ability to offer empathy and support without judgment. Participants also demonstrated high usage of the program, for example, exchanging over 2000 messages with Lyra across the 8 weeks. Human lifestyle modification coaches reviewed Lyra's messages and found them to display strong expertise. This research suggests that sophisticated AI chatbot interventions could be an accessible, affordable, and effective way to provide lifestyle management at a larger scale than is currently possible with in-person programs.

OBJECTIVE:Behavioral weight loss (BWL) programs prescribe reduced energy intake (EI) and moderate-to-vigorous physical activity (MVPA). However, MVPA may also acutely influence EI, and that relation may depend on body mass index (BMI) and post-MVPA cognitions. This study tested if BMI and post-MVPA cognitions moderated the within-subject relation between MVPA and subsequent EI among BWL participants. METHOD:Participants were 91 adults with overweight/obesity participating in a yearlong BWL trial. Data were collected during a 3-week midtreatment assessment, with MVPA measured using Fitbit devices, EI via a self-monitoring app, and BMI via wireless scales (weight) and self-reported height. Post-MVPA cognitions included the following: permissiveness to consume more calories, perceived need to replenish one's body with food, and motivation to lose weight. RESULTS:Multilevel models demonstrated lower BMI and higher perceived need for replenishment amplified the positive relation between MVPA and subsequent EI in the 2-hr post-MVPA period. Exploratory analyses showed increased EI in the 2-hr post-MVPA period was associated with greater daily EI at the trend level, and daily EI was negatively associated with percent weight loss across the midtreatment assessment. CONCLUSION:Individuals with lower BMI and greater perceived need for replenishment post-exercise had higher EI following MVPA versus no MVPA. Findings suggest greater EI acutely following MVPA may predict greater daily EI, which in turn negatively impacts weight loss. Thus, for optimal weight loss outcomes, it may be important to increase awareness of these EI patterns among relevant subpopulations and encourage planning of EI around MVPA to ensure dietary adherence is maintained. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

OBJECTIVE:This study aimed to optimize weight loss outcomes in an online behavioral obesity treatment program by evaluating the effects of five novel intervention components using a factorial experiment informed by the multiphase optimization strategy framework. METHODS:A randomized factorial experiment tested 12-month weight loss resulting from an established online obesity treatment program with randomization to zero to five novel intervention components (interactive video feedback, tailored intervention to promote physical activity, skills for dysregulated eating, virtual reality skills training, and social support with friendly competition). RESULTS:Adults (N = 384; 83% female, 12% male, 5% another sex/gender or did not disclose; 23% racial and/or ethnic minority) with (mean ± SD) age of 53.5 ± 11.7 years and BMI of 35.0 ± 6.1 kg/m2 were randomized. No intervention component independently improved weight loss (p values > 0.199). Interaction terms (p values < 0.01) suggest the combination of interactive video feedback, skills for dysregulated eating, and social support with friendly competition improved weight loss. Mediation analysis indicated that social support and dysregulated eating interventions influenced weight loss outcomes through improvements in social support for physical activity and dietary quality. CONCLUSIONS:This study identified a combination of intervention components that may improve weight loss outcomes compared to the established online treatment program. TRIAL REGISTRATION:ClinicalTrials.gov identifier NCT04520256.

OBJECTIVE:Standard behavioral weight loss (SBT) is a first-line intervention for obesity, but its efficacy with Black adults is limited. Some preliminary work suggests that acceptance-based behavioral therapy (ABT), which integrates mindful decision making, experiential acceptance, and reflection on values, may be a better fit for the needs of Black adults. In this fully powered secondary data analysis, we compared the efficacy of SBT and ABT for Black adults. METHOD:Black and non-Hispanic White adults (N = 737) with overweight or obesity (body mass index = 27-50 kg/m²) were enrolled in one of the five randomized controlled trials investigating the effectiveness of ABT versus SBT. Analyses assessed the impact of race, treatment condition, and their interaction on percent weight loss at posttreatment and first follow-up assessment while controlling for clinical trial. RESULTS:The interaction effects between race and treatment condition on weight loss were trending toward significance (p < .05) at posttreatment, F(1, 729) = 2.74, p = .089, but not at follow-up, F(1, 729) = .003, p = .957. Pairwise comparisons revealed that the disparity in posttreatment weight loss between Black and White participants in the SBT condition (M = 3.5%, p = .001) was attenuated in the ABT condition (M = 1.5%, p = .05). CONCLUSIONS:ABT has promise for supporting Black adults in weight loss attempts, although weight regain after treatment remains persistent for Black and White adults alike. Future research is warranted to continue developing this treatment approach as a tool to reduce health disparities. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

BackgroundCardiovascular disease (CVD) remains the leading cause of death in the United States, and adults aged 40-60 years with specific health conditions are at particularly elevated risk for developing CVD. Physical activity (PA) is a key cardioprotective behavior and many interventions exist to promote PA in this group. Effective promotion requires accurate assessment of PA behavior; as PA is often estimated by averaging across multiple days, a threat to accurate assessment is measurement reactivity, or an atypical increase in PA behavior at the start of measurement periods that may bias conclusions. Evidence for PA measurement reactivity is equivocal, though concern has resulted in recommendations to add or drop PA measurement days from inclusion, which may introduce undue burden on participants. At present, the extent of PA measurement reactivity and the behaviors most likely to be affected (eg, steps vs minutes of exercise) among those at risk for CVD are unclear, as are participant characteristics such as gender and study expectations (eg, intervention vs observation only) that may contribute to differences in these patterns. ObjectiveThe goal of this study is to improve on the current understanding of the extent of PA measurement reactivity and potential moderators among US adults aged 40-60 years with CVD risk factors. MethodsTo achieve this goal, we will conduct coordinated multilevel analyses across 6 studies. Data are from nationally representative, publicly available datasets (observation only: 2 studies) and baseline weeks of observation from behavioral weight loss clinical trials (4 studies), all collected in the United States. The publicly available datasets National Health and Nutrition Examination Survey (NHANES; 2013-2014) and the Midlife in the United States (MIDUS) Study (2004-2009; total n=1385) were used, which are available from the Inter-university Consortium for Political and Social Research website. Behavioral weight loss trials were conducted by the Drexel University Weight Eating and Lifestyle (WELL) Center (2011-2023; total n=444), in person or remotely via Zoom. Relevant data from each study were extracted for adults aged 40-60 years who have ≥1 risk factor for CVD (total n=1832; 11,707 total days of PA measurement with 6-7 days per person). Changes in PA behavior across the measurement period will be examined at the day level, using 2-level multilevel models (days nested within persons) and cross-level interactions (for moderation effects). ResultsThis project was funded in August 2022 and received supplementary funding in September 2023. Dataset acquisition and data cleaning were completed in October 2024. Analyses are expected to be completed in April 2025, and findings are anticipated to be shared in July 2025. ConclusionsResults from this coordinated analysis project will provide the first large-scale estimation of the extent of PA measurement reactivity in an at-risk group. Findings will inform best practices for mitigating potential measurement reactivity in multiday assessments of PA behavior. International Registered Report Identifier (IRRID)DERR1-10.2196/67438

To describe the recent literature on acceptance and commitment therapy (ACT) interventions for individuals with obesity. The review begins with a brief overview of the ACT model, describes seminal work in this area, and examines more recent literature on the use of ACT to improve outcomes among individuals with obesity. Early trials established ACT’s efficacy for weight loss among adults with obesity. More recent research has focused on testing efficacy among adolescents, measuring effects in “real world” settings, refining interventions to optimize outcomes and enhance scalability, and examining outcomes beyond weight (e.g., internalized weight stigma, eating regulation). Current data indicate that ACT-based interventions produce comparable, or, in some cases, superior weight loss compared to standard behavioral interventions. ACT has also shown promise for improving other outcomes of interest. ACT may improve a variety of obesity-related outcomes, although additional research is needed.

Romantic partner undermining is a type of negative social influence that has the potential to make weight loss more challenging and consists of two components: (1) undermining behaviors, or overt romantic partner behaviors including criticism/complaint of weight control or interference behaviors (e.g., offering up high calorie foods), and (2) undermining attitudes, including negative beliefs that a romantic partner has about their significant other’s weight loss attempts. The present study was the first to the authors’ knowledge to investigate romantic partner undermining attitudes and behaviors reported by participants enrolled in in a behavioral weight loss (BWL) intervention, a first line treatment for weight loss. The study also examined whether partner undermining attitudes and behaviors differed by relationship quality and between those who did and did not choose their romantic partner to serve in a support role in the intervention. Participants (N = 128) enrolled in a group-based BWL intervention reported on perceived romantic partner undermining attitudes and behaviors at baseline and 3 months (end of the intensive period of BWL intervention). Results showed that participants perceived minimal romantic partner undermining at baseline (attitudes M = 2.2 ± 0.7, behaviors M = 2.3 ± 1.2) and 3 months (attitudes M = 2.0 ± 0.6, behaviors M = 1.9 ± 1.1). However, participants reported a significant reduction in total undermining attitudes (M change = − 0.2 points) and behaviors (M change = − 0.4 points) from baseline to 3 months (ps <.05), highlighting the potential of group-based BWL interventions to mitigate romantic partner undermining without explicit content focused on undermining. Future research should examine romantic partner undermining across time in varying weight control and relationship conditions and measure undermining at the daily or weekly level to reduce recall bias and improve ecological validity.

Millions of adults in the U.S. with overweight or obesity would like to improve their health via weight loss, yet utilization of evidence-based weight loss interventions is low. Instead, adults commonly attempt self-guided weight loss, which has poor efficacy. When adults use evidence-based interventions (i.e., behavioral, dietary, commercial, surgical, and pharmacological options), long-term engagement is suboptimal. The proposed project is a pilot randomized clinical trial to test the use of patient navigators to increase uptake of and persistence with evidence-based weight loss interventions. Navigators have been successful in other areas of healthcare to facilitate engagement with various treatment and prevention services. However, little data are available on the feasibility, acceptability, or efficacy of a weight loss navigator program in adults. In the present study, participants (N = 68 adults with a BMI >27 kg/m2 interested in weight loss) will be randomly assigned for a 12-month period to either usual care or the navigator condition. Participants in usual care will have no intervention contact, while participants in the navigator condition will attend individual sessions and receive personalized emails from a navigator to support uptake and persistence with an evidence-based weight loss intervention. Assessments will be conducted remotely at months 0, 6, and 12. The primary outcome for the preliminary test of efficacy is weight change after 12 months. This study will inform future iterations of a weight loss navigator program and could impact clinical practice and public health by enhancing the utilization of evidence-based weight loss interventions.

BACKGROUND:Behavioral weight loss interventions achieve only limited weight loss in adolescent samples and weight regain is common. This limited intervention success may be attributed, in part, to adolescents' lack of self-regulation skills essential for lifestyle modification and use of a one-size fits-all approach to produce weight loss in boys and girls. Interventions which teach self-regulation skills, such as Acceptance-Based Therapy (ABT), and are tailored to meet gender-specific concerns, are critical to help adolescents adapt to pervasive biological and environmental influences toward weight gain. OBJECTIVE:This trial tests the effect of an ABT intervention on cardiometabolic health, health-related behaviors, and psychological factors among adolescent girls with overweight or obesity (OW/OB). METHODS:Girls 14-19 years (N = 148; ≥ 40% racial/ethnic minorities) with OW/OB (BMI: ≥ 85th percentile) will be enrolled in the study. Participants will be randomized to one of two 6-month interventions, consisting of either 18 sessions of ABT or 9 sessions of a health education control, an augmented version of standard care for adolescent OW/OB, both led by bachelor's level interventionists. RESULTS:Recruitment is taking place in Philadelphia, USA, from January 2024 to January 2028. Cardiometabolic health markers (adiposity; blood pressure; blood lipids), health-related behaviors (dietary intake; physical activity; sleep), and psychological factors (quality of life; depression; disordered eating; psychological flexibility) will be measured at baseline, mid-treatment, post-treatment, 6-month follow-up, and 12-month follow-up. CONCLUSIONS:This study will provide valuable information on a novel intervention tailored to the needs of adolescent girls with OW/OB to address self-regulation and cardiometabolic health.

Self-weighing is consistently associated with more effective weight control. However, patterns show that participants disengage from their weight control behaviors following weight gain. Women with BMIs in the overweight/obese range (N = 50) enrolled in a long-term behavioral weight loss program completed ecological momentary assessment (EMA) surveys immediately after their daily weigh-ins. Nightly EMA surveys and self-monitoring data through Fitbit measured their weight control behavior that day. On days when participants gained weight (vs. lost or maintained), they reported more negative mood, more guilt/shame, and lower confidence in weight control. Motivation following daily weight gain depended on participants’ overall satisfaction with their weight loss so far: more satisfied participants had marginally higher, but less satisfied participants had marginally lower motivation in response to daily weight gain. Greater guilt/shame and lower motivation after the weigh-in predicted less effective weight control behavior that day (e.g., lower likelihood of calorie tracking, fewer minutes of physical activity). Results demonstrate that even small weight gain is distressing and demoralizing for women in BWL programs, which can lead to goal disengagement. These findings have implications for future BWL interventions, including the potential utility of just-in-time adaptive interventions to promote more adaptive responses in the moments after weigh-ins.

US adults find it challenging to meet disease prevention dietary recommendations and may participate in interventions to improve dietary quality. Social influences outside of the intervention, including level of social support and undermining of healthy eating in the home, may affect an individual’s dietary intake. This secondary analysis examined (1) changes in household social support and undermining of healthy eating across a dietary intervention with household member participation and (2) the relationship between changes in social influences and dietary intake. Adults (N = 62) with low adherence to cancer prevention dietary recommendations recruited from the Philadelphia area participated in a 20-week dietary intervention focused on psychoeducation about NCI dietary recommendations and skills for behavior change. Half of the participants were also randomized to have an adult household member participate in some intervention contacts with them. Participants completed measures of social support and undermining of healthy eating and dietary intake at baseline and post-treatment (20 weeks). Fifty-two participants had available data for baseline and post-treatment (i.e., completers). Household social support of healthy eating increased more among participants randomized to have household involvement in the intervention with a medium effect (η2 = .11). Fruit and vegetable intake significantly increased among participants with meaningful increases in household social support with a large effect (η2 = .37). There were no significant interaction effects of change in household undermining and time on change in dietary intake. Dietary interventions with a household support component show promise for improving household social support and may impact magnitude of dietary change.

ABSTRACTBackgroundUltra‐processed foods (UPFs) are harmful to health but ubiquitous in the modern food environment, comprising almost 60% of the average American diet. This study assessed the feasibility, acceptability, and preliminary efficacy of a novel behavioral intervention designed to reduce UPF intake.MethodsFourteen adults participated in an 8‐week pilot intervention, which consisted of weekly group sessions, individual meal planning sessions, and financial support. Dietary intake was assessed using three Automated Self‐Administered 24‐h Dietary Recalls (ASA24) at both baseline and post‐treatment.ResultsThe intervention was highly feasible and acceptable. Qualitative data demonstrated that participants were enthusiastic about the benefits of reducing UPF intake and found the intervention highly valuable. Participants reduced average daily calories from UPF by 48.9%, number of UPFs consumed by almost half, total daily calorie intake by 612 calories/day, sodium consumption by 37% and sugar consumption by 50%. There were no significant changes in fruit or vegetable intake. Participants lost an average of 3.5 kg (SD = 3.0 kg).ConclusionThis pilot data suggests that behavioral interventions to reduce UPF intake will be well‐received and are capable of success despite the barriers of the United States food environment. Future research should prioritize behavioral interventions targeting UPF consumption alongside policy changes.