Severe obesity, defined as a Body Mass Index (BMI) of 40 kg/m2 or higher, is a growing public health concern associated with increased risks for cardiovascular disease (CVD) and mortality. Lifestyle interventions, particularly those incorporating physical activity (PA), are crucial for managing this condition. However, individuals with severe obesity often exhibit lower levels of PA, both before and after standard behavioral weight loss (SBWL) programs. This article explores the potential of integrating wearable PA monitors into SBWL programs to enhance PA and self-monitoring among the severely obese.
The Challenge of Physical Activity in Severe Obesity
Individuals with severe obesity report less PA both before and after the intervention. This is of concern given the importance of PA on health outcomes and weight maintenance. Considering the importance of PA on health outcomes and weight maintenance, strategies to improve PA within SBWL treatment are needed.
Wearable PA Monitors: A Technological Aid
One strategy for improving PA within SBWL treatment is through the use of wearable PA monitors. These monitors provide “real-time” PA and energy-expenditure feedback and are believed to improve energy balance awareness and reduce the burden of self-monitoring, thereby enhancing motivation and program adherence. Adding this technology to SBWL treatment (SBWL+TECH) for overweight or mildly obese individuals resulted in greater improvements in self-monitoring, self-reported PA, and weight loss at 6 months compared to SBWL alone. Given their low PA, it seems appropriate to test the efficacy of this technology in the severely obese
Study Design and Methodology
To investigate the impact of technology-enhanced SBWL, a study was conducted involving 29 participants with severe obesity (BMI ≥ 40 kg/m2). Participants were between 21-55 years old, had a BMI ≥ 40 kg/m2, and no history of diabetes or bariatric surgery. Moreover, participants reported exercising <150 min/wk at baseline, had no medical contraindications to PA, regular computer and internet access, and passed a behavioral interview prior to randomization. They were randomized into two groups: a standard behavioral weight loss program (SBWL) and SBWL combined with technology (SBWL+TECH). The study aimed to assess whether adding wearable PA monitors to SBWL treatment for severely obese individuals improved PA and self-monitoring following a 6-month intervention. Although we also examined changes in body weight, based upon previous literature we hypothesized that the addition of technology would only have a modest effect on weight loss.
Participants
Twenty-nine individuals were randomized to SBWL (n = 14) or SBWL+TECH (n = 15).
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Measurements
At baseline and 6 months, body weight was measured and PA was objectively assessed for 1-week using the Sensewear armband (Body Media, Pittsburgh, PA, USA). Total minutes/week spent in moderate-to-vigorous intensity physical activity (MVPA) was computed. At 6-months, SBWL+TECH completed a questionnaire assessing the acceptability of the technology. All study procedures were approved by the Miriam Hospital's institutional review board.
Intervention Programs
The 6-month SBWL program consisted of weekly group meetings focusing on behavioral approaches to PA and dietary change. A structured exercise goal progressing to 250 min/week and a calorie intake goal of 1500-1800 kcal/day were prescribed to produce a 1-2 lb/week weight loss. Participants were instructed to monitor food intake and PA behaviors daily using paper diaries, which were returned with written feedback weekly.
SBWL+TECH received the SBWL program described above. The armband, which is worn on the upper arm, objectively assesses PA and energy expenditure and provides up-to-the-minute feedback (e.g., total steps, total MVPA minutes, total energy expenditure, and progress towards goals) via digital display.
Data Analysis
Independent t-tests and chi-square analyses were used to compare treatment groups on demographic, baseline, and adherence variables. One-way ANOVA's were performed to compare SBWL and SBWL+TECH on changes in body weight and MVPA at 6 months, controlling for age, PA monitor wear time, and baseline variables where appropriate. Both completer's analyses and intent-to-treat (ITT) analyses (e.g., baseline weight carried forward) were performed when assessing changes in weight and PA. Effect sizes were calculated using Cohen's d. All analyses were conducted using SPSS for Windows (Version 18, Chicago, IL, USA).
Key Findings
The study revealed several notable outcomes.
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Baseline Characteristics and Retention
Across treatment arms, the mean BMI (45.0 ± 3.9 kg/m2), body weight (126.8 ± 18.0 kg), and demographic characteristics of study participants (82% female, 79% Caucasian) were similar (P > 0.05). However, SBWL participants were significantly older than SBWL+TECH (46.1 ± 9.1 versus 38.7 ± 9.3 years; P = 0.04). Six-month retention did not differ between groups (SBWL: 12/13 versus SBWL+TECH: 11/14 completers; P = 0.19). Those who are not completing the intervention were significantly younger compared to completers (33.6 ± 10.1 versus 44.1 ± 8.4 years; P = 0.03); however groups were similar on all other measures (P > 0.40).
Adherence and Self-Monitoring
The proportion of treatment sessions attended did not differ between groups (SBWL: 75.8 ± 19.6% versus SBWL+TECH: 74.6 ± 26.6%; P = 0.90). Among completers, self-monitoring of dietary intake was considerably greater in SBWL+TECH compared to SBWL (86.2 ± 21.4% versus 71.5 ± 19.4% of possible days; Cohen's d = 0.72), although this did not reach conventional levels of significance (P = 0.098). Moreover, SBWL+TECH wore the armband for 91.3% of possible days for an average of 14.4 hours/day.
Acceptability of Technology
One-hundred percent of participants completing the study indicated that the technology improved the ease of self-monitoring and increased their motivation to adhere to exercise and weight loss goals. Moreover, all but 1 participant reported a desire to use the FIT system in the future to monitor exercise and weight loss progress, with 90% of those reporting they would wear the armband daily.
Changes in Physical Activity
Both intervention arms significantly increased MVPA from baseline to 6 months (P < 0.05). Although not statistically significant (P = 0.33), completer's analyses revealed that the increase in MVPA was approximately 3 times greater in SBWL+TECH (133.0 ± 217 min/wk) compared to SBWL (44.8 ± 124.6 min/wk), which was a moderate effect (Cohen's d = 0.50; Figure 1). Baseline to 6-month changes in physical activity stratified by treatment arm and type of analyses performed. MVPA = moderate-to-vigorous intensity physical activity; SBWL = standard behavioral weight loss intervention; SBWL + TECH = standard behavioral weight loss program plus technology component.
Weight Loss Outcomes
Although differences in PA between groups did not meet conventional thresholds of significance, SBWL+TECH increased their moderate-to-vigorous intensity PA by 132.9 ± 216.8 min/week, which was 3 times greater than SBWL (44.8 ± 124.3 min/week; P = 0.27; Cohen's d = 0.50). There was a trend for SBWL+TECH to self-monitor for a greater proportion of days compared to SBWL (86.2 ± 21.4% versus 71.5 ± 19.4%; P = 0.098; Cohen's d = 0.72). The difference in weight loss between groups was modest (SBWL+TECH: −10.0 ± 7.1% versus SBWL: −7.8 ± 6.7%; P = 0.46).
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Discussion
This study was the first to examine the feasibility of adding an objective PA monitor to SBWL treatment for severely obese individuals. Furthermore, it was the first to report objectively-assessed changes in PA following an SBWL intervention. This is significant given the low levels of PA and previously observed discrepancy between self-report and objective MVPA in this population. In the current study, 6-month changes in objectively measured MVPA were low in SBWL (45 min/week) and three times as large in SBWL+TECH (133 min/week). Although not statistically significant, the 0.50 effect size observed is relatively high for PA intervention trials. Moreover, these objective findings are in concordance with previous studies in nonseverely obese cohorts, which reported that the change in self-report MVPA was 2 and 4 times greater in SBWL+TECH compared to SBWL. It is well documented that the effect of PA on initial weight loss is modest (~2-3 kg), thus the additional 2.2% weight loss achieved by SBWL+TECH is not surprising. This magnitude of difference in weight loss between groups may be associated with the additional 88 min/wk (~400-500 kcal/wk) increase in PA observed in SBWL+TECH. Moreover, this finding is in accordance with previous studies utilizing this technology in less obese individuals which reported an additional 2% weight loss in SBWL+TECH compared to SBWL. Given that high PA is a primary predictor of weight maintenance, it is plausible that similar technology-based approaches may be efficacious for increasing PA and improving long-term weight loss success. This preliminary study also demonstrates the feasibility of adding objective PA monitors to SBWL treatment for the severely obese. On average, SBWL+TECH wore the armband for >90% of possible days and 90% of waking hours, with 100% of participants reporting that the technology increased motivation and improved the ease of self-monitoring. Moreover, SBWL+TECH self-monitored for an additional 15% of possible days, compared to SBWL, which is considered a moderate-to-large effect size, although not statistically significant.
Strengths and Limitations
This study is strengthened by the use of objective measures to capture 6-month changes in PA, and also through the application of this technology to a severely obese cohort. However, this pilot study was not powered to detect significant differences in PA between treatment arms. It is estimated that 128 individuals (n = 64/group) are needed to detect the observed effect size of 0.50 with 80% power at P < 0.05. Additionally, it is unclear whether the acceptability ratings of the TECH system were similar in completers and noncompleters.
Conclusion
These preliminary findings suggest that PA monitors may be one strategy for increasing PA among the severely obese. These findings add to the scant literature demonstrating that severely obese individuals can achieve significant weight losses through SBWL treatment and that adding technology with real-time PA feedback is well accepted and may increase self-monitoring and PA in this population. Larger, long-term trials are needed.