Psychological and behavioral responses to daily weight gain during behavioral weight loss treatment.

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.

A Proof-of-Concept Pilot Test of a Behavioral Intervention to Improve Adherence to Dietary Recommendations for Cancer Prevention.

OBJECTIVES: Prevention programs that can help adults improve the quality of their diets to reduce cancer risk are needed. This Phase IIa study prospectively tested a mHealth intervention designed to improve adherence to dietary quality guidelines for cancer prevention. METHODS: All participants (N = 62) received nutrition education and a self-regulation skills curriculum, with a primary target of changing grocery shopping behavior. Using a randomized, factorial design, the study varied whether each of the following 4 components were added to the 20-week intervention: (1) location-triggered app messaging, delivered when individuals arrived at grocery stores, (2) reflections on benefits of change, delivered with extra coaching time and tailored app messages, (3) coach monitoring, in which food purchases were digitally monitored by a coach, and (4) involvement of a household member in the intervention. RESULTS: Benchmarks were successfully met for recruitment, retention, and treatment acceptability. Across conditions, there were significant reductions in highly processed food intake (P < .001, η2 = .48), red and processed meat intake (P < .001, η2 = .20), and sugar-sweetened beverage intake (P = .008, η2 = .13) from pre-to post-treatment. Analyses examining whether each intervention component influenced change across time found that participants who received coach monitoring increased their intake of fruits, vegetables, and fiber, whereas those with no coach monitoring had less improvement (P = .01, η2 = .14). The improvement in red and processed meat was stronger among participants with household support ON, at a marginally significant level, than those with household support OFF (P = .056, η2 = .07). CONCLUSION: This study showed feasibility, acceptability, and preliminary signals of efficacy of a remotely delivered intervention to facilitate adherence to dietary guidelines for cancer prevention and that coach monitoring and household support may be especially effective strategies. A fully powered clinical trial is warranted to test an optimized version of the intervention that includes nutrition education, self-regulation skills training, coach monitoring, and household member involvement. TRIAL REGISTRATION: ClinicalTrials.gov NCT04947150.

The Role of Physical Activity in Long-term Weight Loss: 36-month Results From a Randomized Controlled Trial.

BACKGROUND: Physical activity (PA) may promote long-term weight loss, but facilitating high levels of PA in behavioral weight loss programs is challenging. PURPOSE: This study reports the 36-month follow-up of a behavioral weight loss trial that tested the efficacy of increasing the emphasis on PA during treatment and using traditional or acceptance-based therapy (ABT) for this purpose. We also examined the extent to which long-term weight loss differed by PA pattern and tested if individual differences in eating behavior moderated this relationship. METHODS: Participants (N = 320) were randomized to (1) standard behavioral weight loss treatment (BT), (2) BT with a focus on PA, or (3) ABT with a focus on PA. Weight loss and PA were measured at 24- and 36-month follow-up. RESULTS: There were no differences between conditions in weight loss or PA at 24 or 36 months. Participants consistently engaging in high PA experienced the greatest weight losses. The positive impact of PA on weight loss was more pronounced among those with low emotional eating and those who believed that exercise did not affect their appetite. CONCLUSIONS: Findings emphasize the difficulty of improving long-term PA among adults with overweight/obesity beyond what standard behavioral weight loss treatment achieves. This study highlights the need to develop new PA treatment strategies, and suggests that ABT for weight loss may be more effective when applied to eating behavior versus PA. Results also demonstrate the importance of addressing problematic eating behavior and cognitions to fully realize the benefits of PA for weight loss. CLINICAL TRIAL INFORMATION: ClinicalTrials.gov identifier: NCT02363010.

Do monthly coaching calls influence proximal participant adherence in a behavioral weight loss program?

Participants who receive continued coach contact following behavioral weight loss treatment are more successful in maintaining their weight loss long-term. The current study examines whether these contacts have dynamic effects, such that participants are most adherent to the prescribed weight loss behaviors in the days after the call, when motivation and goal salience may be heightened, than they are as time goes on. The current study examined the trajectory of calorie intake, physical activity, weight, and self-monitoring behavior in the fourteen days after a monthly coaching call among participants completing the maintenance phase of a behavioral weight loss trial. For physical activity outcomes, caloric intake, and weight, there were no changes across time. Participants did have the highest adherence and quality of dietary self-monitoring immediately after the call, which diminished over time. Coach contact may continually renew commitment to this burdensome but critical behavior. Likelihood of self-weighing showed an opposite trend, where participants were more likely to weigh themselves in the days more distal from the coach call. Results can inform the timing and content of future coach contact to promote weight control.

Overlapping and distinct relationships between hedonic hunger, uncontrolled eating, food craving, and the obesogenic home food environment during and after a 12-month behavioral weight loss program.

Hedonic hunger, reward-driven eating outside of biological need, is a newer construct in eating behavior research. During behavioral weight loss (BWL), greater improvements in hedonic hunger are associated with higher weight loss, but it remains unclear if hedonic hunger predicts weight loss independent of more well-established, similar constructs (uncontrolled eating and food craving). Research also is needed to understand how hedonic hunger interacts with contextual factors (e.g., obesogenic food environment) during weight loss. Adults (N = 283) in a 12-month randomized controlled trial of BWL were weighed at 0, 12, and 24 months, and completed questionnaires assessing hedonic hunger, food craving, uncontrolled eating, and the home food environment. All variables improved at 12 and 24 months. Decreases in hedonic hunger at 12 months were associated with higher concurrent weight loss, but not when accounting for improvements in craving and uncontrolled eating. At 24 months, reduction in craving was a stronger predictor of weight loss than hedonic hunger, but improvement in hedonic hunger was a stronger predictor of weight loss than change in uncontrolled eating. Changes to the obesogenic home food environment failed to predict weight loss, regardless of levels of hedonic hunger. This study adds novel information on the individual and contextual factors associated with short- and long-term weight control, which can help refine conceptual models and treatment strategies.

Latent Profile Analysis of Physical Activity Motivation during Behavioral Weight Loss Treatment.

Participants in behavioral weight loss (BWL) treatment often struggle to meet and maintain physical activity (PA) prescriptions; improving participants' motivation for the behavior is a potential intervention strategy. Self-Determination Theory (SDT) outlines a continuum of qualitatively different dimensions of motivation, suggesting that more self-determined forms of motivation should predict more PA, whereas less self-determined forms of motivation should be unrelated or negatively related to PA. Although SDT has ample empirical support, most existing research in this area has used statistical analyses that oversimplify the complex, interdependent relationships between dimensions of motivation and behavior. This study's purpose was to explore commonly occurring motivational "profiles" for PA based on the SDT dimensions of motivation (amotivation, external, introjected, integrated/identified, and intrinsic motivation) and how these profiles relate to PA behavior among participants with overweight/obesity (N=281, 79.4% female) at baseline and six months into BWL treatment. Latent profile analysis determined that three motivational profiles fit the data best at both timepoints and the profile characterized by high self-determined (i.e., integrated/identified and intrinsic) motivation and moderate introjected motivation was by far the most common. There were no differences in physical activity behavior across motivational profiles, which contrasts previous literature. Findings suggest that participants who take the initiative to sign up for intensive BWL programs may have sufficiently high PA motivation, which may be a poor predictor of their actual behavior. Future research should examine these relationships later in treatment, when motivation may have more variability, as well as among participants who initiate lower-commitment weight loss programs (e.g., self-help).

BestFIT Sequential Multiple Assignment Randomized Trial Results: A SMART Approach to Developing Individualized Weight Loss Treatment Sequences.

BACKGROUND: State-of-the-art behavioral weight loss treatment (SBT) can lead to clinically meaningful weight loss, but only 30-60% achieve this goal. Developing adaptive interventions that change based on individual progress could increase the number of people who benefit. PURPOSE: Conduct a Sequential Multiple Assignment Randomized Trial (SMART) to determine the optimal time to identify SBT suboptimal responders and whether it is better to switch to portion-controlled meals (PCM) or acceptance-based treatment (ABT). METHOD: The BestFIT trial enrolled 468 adults with obesity who started SBT and were randomized to treatment response assessment at Session 3 (Early TRA) or 7 (Late TRA). Suboptimal responders were re-randomized to PCM or ABT. Responders continued SBT. Primary outcomes were weight change at 6 and 18 months. RESULTS: PCM participants lost more weight at 6 months (-18.4 lbs, 95% CI -20.5, -16.2) than ABT participants (-15.7 lbs, 95% CI: -18.0, -13.4), but this difference was not statistically significant (-2.7 lbs, 95% CI: -5.8, 0.5, p = .09). PCM and ABT participant 18 month weight loss did not differ. Early and Late TRA participants had similar weight losses (p = .96), however, Early TRA PCM participants lost more weight than Late TRA PCM participants (p = .03). CONCLUSIONS: Results suggest adaptive intervention sequences that warrant further research (e.g., identify suboptimal responders at Session 3, use PCMs as second-stage treatment). Utilizing the SMART methodology to develop an adaptive weight loss intervention that would outperform gold standard SBT in a randomized controlled trial is an important next step, but may require additional optimization work. CLINICAL TRIAL INFORMATION: ClinicalTrials.gov identifier; NCT02368002.

Validation of the food craving Acceptance and action questionnaire (FAAQ) in a weight loss-seeking sample.

OBJECTIVE: The Food Craving Acceptance and Action Questionnaire (FAAQ) was developed to measure psychological flexibility around food-related internal experiences (e.g., thoughts, feelings, urges) and has two subscales, acceptance and willingness. However, the FAAQ factor structure has not yet been systematically validated with a clinically relevant sample. METHODS: Two weight-loss treatment seeking samples (total N = 462; 80.4% female) ages 18 to 70 (M = 52.6, SD = 9.8) completed the FAAQ before and after group-based treatment of overweight or obesity. RESULTS: Confirmatory factor analysis on the FAAQ's previously observed two-factor model produced poor model fit. An alternative 7-item model removing specific items that contributed to poor fit and were conceptually relevant to remove provided good model fit. The resulting revised 7-item FAAQ (items 1,3,6 removed) had adequate internal consistency and significant predictive validity for the Total score and subscales, and showed initial construct validity for the Total score. CONCLUSIONS: Results from this study suggest researchers and clinicians should now use the 7-item FAAQ-II, which retains the Willingness and Acceptance subscales. Future research is needed with other relevant samples to confirm the FAAQ-II's factor structure and psychometric properties.

Perceived influence of wearable fitness trackers on eating disorder symptoms in a clinical transdiagnostic binge eating and restrictive eating sample.

Wearable fitness trackers are an increasingly popular tool for measuring physical activity (PA) due their accuracy and momentary data collection abilities. Despite the benefits of using wearable fitness trackers, there is limited research in the eating disorder (ED) field using wearable fitness trackers to measure PA in the context of EDs. Wearable fitness trackers are often underused in ED research because there is limited knowledge about whether wearable fitness trackers negatively or positively impact PA engagement and ED symptoms in individuals with EDs. The current study aimed to assess the perceived impact wearable fitness trackers have on PA engagement and ED symptoms over a 12-week CBT treatment for 30 individuals with binge eating and restrictive eating that presented to treatment engaging or not engaging in maladaptive exercise. Participants in the maladaptive exercise group (n = 17) and non-maladaptive exercise group (n = 13) wore a fitness tracker for 12 weeks and completed questionnaires assessing participants' perceptions of the fitness trackers' influence on ED symptoms and PA engagement throughout treatment. Results demonstrated a small percentage of individuals perceived the fitness tracker influenced ED behaviors or PA engagement, and there were mixed results on whether participants positively or negatively perceived the fitness tracker influenced them to engage in ED behaviors or PA engagement. Although preliminary, these results demonstrate the need to continue using objective measurements of PA via wearable fitness trackers to further our understanding of the positive and negative effects of fitness trackers on clinical ED samples.Level of Evidence: Level 1, randomized controlled trial.

Weight-Related Information Avoidance Prospectively Predicts Poorer Self-Monitoring and Engagement in a Behavioral Weight Loss Intervention.

BACKGROUND: Self-monitoring is a key component of behavioral weight loss (BWL) interventions. Past research suggests that individuals may avoid self-monitoring in certain contexts (e.g., skipping self-weighing after higher-than-usual calorie intake). However, no studies have attempted to quantify individuals' inclination to avoid information about their weight control ("weight-related information avoidance"; WIA) or prospectively examined its implications for treatment engagement and outcomes in BWL programs. PURPOSE: Characterize WIA using a validated questionnaire among adults enrolled in BWL treatment and examine whether WIA prospectively predicts self-monitoring adherence, session attendance, treatment discontinuation, or weight loss. METHODS: Participants (N = 87; MBMI = 34.9 kg/m2, 83% female) completed a measure of WIA prior to starting a 12 week, group-based BWL intervention. Participants were given digital self-monitoring tools and instructed to self-monitor their food intake daily, physical activity daily, and body weight weekly (Weeks 1-10) and then daily (Weeks 11-12). Session attendance and treatment discontinuation were recorded. Weight was measured in-clinic pretreatment and posttreatment. RESULTS: While mean WIA was low (M = 2.23, standard deviation [SD] = 0.95; potential scale range: 1-7), greater WIA predicted poorer attendance (r = -.23; p = .03) and poorer self-monitoring of physical activity (r = -.28; p = .009) and body weight (r = -.32; p = .003). WIA did not predict food monitoring (p = .08), treatment discontinuation (p = .09), or 12 week weight loss (p = .91). CONCLUSIONS: Greater WIA, as assessed via a brief questionnaire, may place individuals at risk for poorer self-monitoring and treatment engagement during BWL. Further research on the implications of WIA in the context of weight management is warranted, including evaluation of correlates, moderators, and mechanisms of action of WIA. CLINICAL TRIAL REGISTRATION: NCT03337139.

Physical activity assessment among men undergoing genetic counseling for inherited prostate cancer: a teachable moment for improved survivorship.

BACKGROUND: Genetic counseling (GC) presents an opportunity to address modifiable cancer risk factors, such as obesity, which is impacted by non-adherence to physical activity (PA) guidelines. Adherence to PA guidelines has not been assessed among men undergoing GC for prostate cancer (PCA). We conducted a targeted analysis of men undergoing PCA GC to assess adherence to PA recommendations. METHODS: Using a cross-sectional design, a total of 158 men from the Genetic Evaluation of Men (GEM) study at two academic cancer centers with a diagnosis or at risk for PCA completed a structured lifestyle survey, including questions about the number of days and intensity of PA over the past year. One-sample t tests assessed adherence of participants to PA recommendations. Chi-square analyses compared differences in PA adherence by PCA status, aggressiveness, family history, and body mass index. Logistic regression analyses identified predictors of PA adherence. RESULTS: High proportions of GEM participants were overweight (44.9%) or obese (38.0%, p = 0.002). Men with PCA engaged in less moderate (p = 0.019) and vigorous (p = 0.005) aerobic activity than men without PCA. Higher education was predictive of adherence to light (p = 0.008), moderate (p = 0.019), and vigorous (p = 0.002) intensity PA. Older age (p = 0.015) and higher education (p = 0.001) were predictive of adherence to strength-based recommendations. CONCLUSIONS: High proportions of men receiving PCA GC were overweight/obese and lacked adherence to PA recommendations. GC represents a teachable moment to address PA to reduce cancer risk and promote cancer survivorship.

Obesity in early onset breast cancer in African American patients.

Obesity is a modifiable risk factor in breast cancer patients and is predictive of disease outcomes in early-onset breast cancer survivors. The purpose of this review is to summarize the current evidence in the association between early-onset breast cancer and obesity, specifically in African-American women. Reviewing the molecular mechanisms and social determinants of disease in this population can provide a foundation for future interventions in prevention, detection, and treatment aiming at improving outcomes for young breast cancer patients.

Physical discomfort intolerance as a predictor of weight loss and physical activity in a lifestyle modification program.

This study examined physical discomfort intolerance (DI) as a baseline predictor of weight loss and physical activity outcomes, and assessed whether changes in DI during the initial phase of weight loss prospectively predicted long-term treatment outcomes among adults enrolled in a group-based lifestyle modification program for obesity. DI was measured at baseline and 6 months, and weight and accelerometer-measured physical activity were assessed at baseline, 6 months, and 12 months. Baseline DI was not related to weight loss or physical activity at either timepoint. Change in DI during the first 6 months of treatment was not related to concurrent (i.e., 6-month) weight loss and physical activity, but was significantly predictive of weight loss and physical activity at 12 months. Assessing early changes in DI may help to identify individuals at risk for suboptimal outcomes. Future research should evaluate behavioral weight loss interventions designed to target DI.

The association between negative affect and physical activity among adults in a behavioral weight loss treatment.

INTRODUCTION: Many individuals engaged in behavioral weight loss make suboptimal increases in moderate-to-vigorous physical activity (MVPA). Theoretically, reductions in negative affect could reinforce MVPA. However, little work has been done investigating the association between facets of negative affect (e.g., average levels of negative affect, variability in negative affect) and MVPA among individuals attempting to increase MVPA as part of a behavioral weight loss attempt. METHODS: Participants (n = 139) provided data at month 6 of a year-long behavioral weight loss program (at which point the prescription for MVPA had reached the highest level). Participants wore an accelerometer and provided EMA ratings of affect over the same week. RESULTS: Individuals engaged in more frequent and longer periods of MVPA had lower average negative affect and variability in negative affect across the assessment period. Lower negative affect one day predicted greater time spent in MVPA on the next day; lower variability in negative affect than one's average level also predicted greater time spent in MVPA on the next day. Greater engagement in MVPA than one's own mean on one day did not predict mean or variability in affect. DISCUSSION: Engaging in MVPA over time may reduce negative affect, while lower negative affect may increase motivation to engage in MVPA. Importantly, day-to-day effects indicated that affect is an important acute predictor of MVPA behavior. It is possible that individuals, particularly those with higher negative affect or variability in negative affect, may benefit from the inclusion of skills to manage negative affect in programs prescribing physical activity.

Physical Activity Intentions and Behavior Mediate Treatment Response in an Acceptance-Based Weight Loss Intervention.

BACKGROUND: Acceptance-based treatment (ABT) for weight loss has shown promise for improving outcomes relative to standard behavioral treatment (SBT). One way in which ABT may improve outcomes is through increasing physical activity (PA) intentions and behavior but little research has examined these as mediators of ABT on weight change. PURPOSE: This study sought to examine ABT's effects on intentions for PA and several objectively measured PA variables during treatment and analyze PA intentions and behaviors as mediators of ABT's effect on weight loss. METHODS: Participants (N = 189) with overweight/obesity randomized to 1 year of either ABT or SBT completed ecological momentary assessment of PA intentions, accelerometer-based PA assessment, and had weight measured at baseline, mid-treatment, and end of treatment. RESULTS: ABT had a significantly higher increase than SBT in PA intention minutes at mid-treatment and end of treatment (p < 0.001), and both groups had nonlinear increases in moderate-to-vigorous physical activity (MVPA) that were not significantly different. Sequential mediation models found that ABT's effect on weight loss was partially mediated by higher PA intention minutes at mid-treatment leading to increased MVPA minutes per week. Increased MVPA minutes were obtained by participants increasing the number of days with MVPA bouts. CONCLUSIONS: ABT's effect on weight loss throughout treatment resulted, in part, from participants increasing their intentions for PA. Controlling for group, higher PA intentions were associated with more PA obtained through more days with exercise.

Executive Functioning as a Predictor of Weight Loss and Physical Activity Outcomes.

BACKGROUND: Executive functioning, which is fundamental for carrying out goal-directed behaviors, may be an underappreciated predictor of outcomes in lifestyle modification programs for adults with obesity. PURPOSE: This study tested the hypotheses that higher levels of baseline executive functioning would predict greater weight loss and physical activity after 6 months of behavioral treatment. METHODS: Participants (N = 320) were recruited from the community and provided with 16 treatment sessions. Executive functioning was measured with the tower task component of the Delis-Kaplan Executive Function System (D-KEFS). At months 0 and 6, weight was measured in the clinic and physical activity was measured with tri-axial accelerometers. RESULTS: Baseline D-KEFS achievement score, rule violations, and completion time significantly predicted weight loss at 6 months. For example, among participants without any rule violations (n = 162), weight loss averaged 11.0%, while those with rule violations (n = 158) averaged 8.7% weight loss. Rule violations also significantly predicted physical activity at 6 months. Among participants without any rule violations, physical activity at 6 months averaged 169.8 min/week, versus 127.2 min/week among those with rule violations. CONCLUSIONS: Particular aspects of executive functioning may predict the relative ease or difficulty of changing eating and exercise-related behaviors, albeit with small effect sizes. This study is the first to our knowledge to detect a predictive relationship between components of executive functioning and objectively measured physical activity in adult lifestyle modification, and one of the first to predict weight loss in adults using an objective measure of executive functioning. CLINICALTRIALS.GOV REGISTRATION NUMBER: NCT02363010.

The relationship of weight suppression to treatment outcomes during behavioral weight loss.

Many adults enter behavioral weight loss (BWL) programs at a weight below their highest lifetime weight. The discrepancy between highest lifetime weight and current weight is known as weight suppression (WS). Research has yet to characterize WS during BWL or investigate its relation to weight loss outcomes or treatment acceptability. Adults (N = 272) in a 12-month BWL program were assessed. WS was calculated by subtracting measured baseline weight from self-reported highest lifetime weight. Participants with higher WS lost significantly less weight than those with lower WS during treatment, although they still had clinically meaningful weight losses (e.g., participants with WS above the median: 7.8 kg; participants with WS below the median: 12.0 kg). WS was unrelated to weight losses at 24-month follow-up. Controlling for weight loss, treatment acceptability was unrelated to WS. BWL appears appropriate for those with high WS, but future research should aim to improve outcomes in this group.

Participant and interventionist perceptions of challenges during behavioral weight loss treatment.

No prior studies have examined how interventionists' perceptions of participants' weight control challenges or the agreement between participants and interventionists on these perceptions relate to outcomes during group-based behavioral weight loss treatment. This study characterized participants' and interventionists' perceptions of, and agreement about, weight control challenges and assessed how these factors relate to weight loss. Three months into treatment, participants and interventionists independently selected three weight control challenges believed to be most relevant for each participant. Weight was measured at baseline, 3 months, and 12 months. Interventionists and participants had "no" (κ < 0) or "slight" (0 < κ< .20) agreement on most challenges. Although endorsement of certain challenges by participants and/or interventionists was related to 3- and 12-month weight losses, agreement between participants and interventionists was unrelated to weight loss at either time point. Additional research is needed to better understand the role of perceived challenges and participant/interventionist agreement about challenges on treatment outcomes.

Computerized neurocognitive training for improving dietary health and facilitating weight loss.

Nearly 70% of Americans are overweight, in large part because of overconsumption of high-calorie foods such as sweets. Reducing sweets is difficult because powerful drives toward reward overwhelm inhibitory control (i.e., the ability to withhold a prepotent response) capacities. Computerized inhibitory control trainings (ICTs) have shown positive outcomes, but impact on real-world health behavior has been variable, potentially because of limitations inherent in existing paradigms, e.g., low in frequency, intrinsic enjoyment, personalization, and ability to adapt to increasing ability. The present study aimed to assess the feasibility, acceptability, and efficacy of a gamified and non-gamified, daily, personalized, and adaptive ICT designed to facilitate weight loss by targeting consumption of sweets. Participants (N = 106) were randomized to one of four conditions in a 2 (gamified vs. non-gamified) by 2 (ICT vs. sham) factorial design. Participants were prescribed a no-added-sugar diet and completed 42 daily, at-home trainings, followed by two weekly booster trainings. Results indicated that the ICTs were feasible and acceptable. Surprisingly, compliance to the 44 trainings was excellent (88.8%) and equivalent across both gamified and non-gamified conditions. As hypothesized, the impact of ICT on weight loss was moderated by implicit preference for sweet foods [F(1,95) = 6.17, p = .02] such that only those with higher-than-average implicit preference benefited (8-week weight losses for ICT were 3.1% vs. 2.2% for sham). A marginally significant effect was observed for gamification to reduce the impact of ICT. Implications of findings for continued development of ICTs to impact health behavior are discussed.

Can the artificial intelligence technique of reinforcement learning use continuously-monitored digital data to optimize treatment for weight loss?

Behavioral weight loss (WL) trials show that, on average, participants regain lost weight unless provided long-term, intensive-and thus costly-intervention. Optimization solutions have shown mixed success. The artificial intelligence principle of "reinforcement learning" (RL) offers a new and more sophisticated form of optimization in which the intensity of each individual's intervention is continuously adjusted depending on patterns of response. In this pilot, we evaluated the feasibility and acceptability of a RL-based WL intervention, and whether optimization would achieve equivalent benefit at a reduced cost compared to a non-optimized intensive intervention. Participants (n = 52) completed a 1-month, group-based in-person behavioral WL intervention and then (in Phase II) were randomly assigned to receive 3 months of twice-weekly remote interventions that were non-optimized (NO; 10-min phone calls) or optimized (a combination of phone calls, text exchanges, and automated messages selected by an algorithm). The Individually-Optimized (IO) and Group-Optimized (GO) algorithms selected interventions based on past performance of each intervention for each participant, and for each group member that fit into a fixed amount of time (e.g., 1 h), respectively. Results indicated that the system was feasible to deploy and acceptable to participants and coaches. As hypothesized, we were able to achieve equivalent Phase II weight losses (NO = 4.42%, IO = 4.56%, GO = 4.39%) at roughly one-third the cost (1.73 and 1.77 coaching hours/participant for IO and GO, versus 4.38 for NO), indicating strong promise for a RL system approach to weight loss and maintenance.