Microrandomized Trial to Optimize Use of Burden-reducing Self-monitoring Approaches in Behavioral Obesity Treatment

This clinical trial is a 24-week micro-randomized trial (MRT) designed to optimize the use of dietary self-monitoring (SM) strategies during behavioral obesity treatment (BOT). Self-monitoring is considered the cornerstone of BOT because it enables individuals to regulate behaviors that influence energy balance and weight loss. However, adherence to traditional full dietary SM (i.e., recording all food and beverages consumed each day) declines rapidly over time due to its burden, leading to poorer weight loss outcomes.

To address this problem, this study evaluates five SM approaches that vary in intensity and burden:

1. Full dietary SM: Recording all food and drink consumed, with calorie estimates, every day.
2. Reduced-frequency dietary SM: Recording all food and drink consumed, with calorie estimates, on 3 days per week.
3. Self-monitoring of dietary lapses only: Recording only episodes of eating or drinking that likely cause weight gain or put weight loss at risk.
4. Smartwatch-based SM of energy intake: Using a smartwatch that detects eating gestures and estimates energy intake (i.e., "calories") via built-in sensors.
5. Body weight SM only: Weighing daily using a smart scale that automatically syncs data to the online treatment platform.

All participants (N=275 adults with overweight or obesity, aged 18-70) will receive a 24-week evidence-based, online BOT. This BOT includes interactive multimedia lessons on nutrition, physical activity, and behavioral skills for weight management, with individualized calorie and activity goals, self-regulation training, and automated feedback. The only experimental manipulation is the self-monitoring approach assigned every two weeks.

At the start of treatment and every two weeks thereafter, participants will be randomly assigned to one of the five SM approaches (12 total randomizations per participant). Randomization probabilities favor assignment to full dietary SM at treatment initiation, then gradually equalize across approaches. At each randomization, participants will be notified of their new SM assignment and receive a brief online training for that approach. A member of the research team will conduct a short online video call to confirm comprehension and assist with troubleshooting.