The goal of this study is to test whether an acceptance based intervention can modify the relationship between heart rate and perceived exertion/negative during physical activity among individuals who have a high degree of internalized weight bias.

In this two-phase pilot, we will first test in a controlled setting whether an acceptance-based intervention can modify the relationship between Heart Rate and perceived exertion/negative affect during moderate intensity physical activity among individuals high in internalized weight bias (Phase 1) and then evaluate these mechanisms in real-time during uptake of a two-week physical activity prescription (Phase 2). Using a 2x2 factorial design, we will randomize individuals with Body Mass Index (BMI) ≥25, high and low internalized weight bias, and insufficient activity (<60 min of moderate physical activity/week) to receive a 90-minute acceptance-based intervention workshop versus a multi-health behavior education condition prior to completing a 30-minute session of supervised, moderate intensity treadmill walking. Heart rate, self-reported perceived exertion and affect will be assessed throughout physical activity.

For Phase 2, all participants from Phase 1 will receive a two-week physical activity prescription consistent with National Guidelines (150 minutes moderate intensity aerobic physical activity, recommended in 30-minute bouts) to determine the effect of treatment condition on subsequent adherence to physical activity. Physical activity adherence will be monitored with Actigraphy and Ecological Momentary Assessment (repeated daily surveys via smartphone) will be used to evaluate participant self-efficacy, intention, motivation for physical activity in near real-time.

Inclusion Criteria:

• 18-60 years old,
• BMI 25-40 kg/m2
• insufficiently active (<60 minutes of moderate intensity activity per week).
• High/low internalized weight bias
• Access to personal smartphone device and willing to download free smartphone app for data collection

Exclusion Criteria:

• Comorbid issues that might interfere with ability to engage in physical activity
• Factors that would influence ability to complete study protocol (e.g., cognitive, psychological)
• medication that would affect heart rate (e.g., beta blocker),
• women who are nursing or pregnant

Consistent with Lifespan IRB policy, any interested individuals seeking access to conduct secondary analysis of study data will be required to submit a formal agreement with the PI, or designee, that 1) the data will be used for research purposes only and will not be used to identify any individual participants, 2) the data will be secured using appropriate computer technology, and 3) that the data will be destroyed or returned to the PI after the analyses are complete. This will be mediated by IRB involvement and the PI retains the right to deny any request for qualitative data access.

Generally, we work with the requestor/user to provide the minimum data necessary for their research question to support resource sharing while maintaining patient confidentiality.

Individuals conducting study assessments will remain masked to treatment condition.

Interventions have been matched for time, so that masked assessors are unable to note a discrepancy in treatment condition throughout study procedures. Intervention staff will be responsible for preparing the room with materials and for relocating participant from intervention room back to the assessment room so that the masked assessor is not able to view any materials left behind from the treatment condition. Participants will be reminded by study staff throughout study procedures that they should not disclose their treatment condition or information about their intervention meeting that could inform masked staff of randomization.