# A micro-randomized trial of JITAI messaging to improve adherence to multiple weight loss behaviors in young adults

> **NIH NIH R01** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2022 · $769,818

## Abstract

PROJECT ABSTRACT
An estimated 1 in 2 US adults will have obesity by 2030, which is a major cause of morbidity and mortality. The
highest risk of weight gain is among young adults ages 18-35 years. In-person behavioral interventions
generally produce clinically significant weight losses, but cost and reduced reach limit their ability to impact
obesity at a population level. Web-based interventions that mimic the structure of weekly face-to-face
treatment have proven a viable alternative, though weight losses are generally smaller than in-person
treatment. Mobile treatments have the potential for high reach, but have been less effective, producing 1-3 kgs
over 6 months. Newer digital intervention approaches called “just-in-time adaptive interventions” (JITAIs)
promise to improve upon mobile outcomes by offering adaptive, personalized feedback on behavior, which
consists of providing the “right type of support” at “the right time” rather than on a fixed schedule. This “just-in-
time,” or JIT, approach is made possible by the emergence of low-cost and widely available digital health tools
that allow for the collection of continually updated health data. However, to date, no JITAIs have successfully
targeted multiple weight-related behaviors (weighing, activity, and diet), and there has been no systematic
examination of what types of messaging interventions best promote adherence to these three weight loss
behaviors, for whom they are effective, and under what conditions. To address this problem, we will use a
micro-randomized trial to evaluate the effects of 7 types of intervention messages targeting specific behavior
change techniques (i.e., BCT messages) delivered in JIT moments on daily achievement of behavioral goals
among n=201 young adults with overweight and obesity. All participants will receive a 6-month behavioral
weight loss intervention using our Nudge mobile app, which includes evidence-based weekly lessons, tailored
feedback, self-monitoring, and daily BCT messages. Participants will receive a wireless scale, activity tracker,
and track “red” foods (high-calorie foods) in the app and have 3 goals: weigh daily, a daily active minutes goal
that gradually increases if met, and a daily red foods limit. At 3 decision points per day, participants will be
micro-randomized to receive or not receive 1 of 7 types of BCT messages. Each intervention message has
unique decision rules for availability. Candidate intervention message options have been carefully selected
from empirical evidence, tested in our prior studies, or are from our pilot micro-randomized trial. Assessments
will occur daily, and at 0, 3 and 6 months, to accomplish the following specific aims: 1) Evaluate the effects of
each behavior change technique message (i.e., BCT message) on daily adherence to weight loss behaviors; 2)
Determine whether the effects of BCT messages on proximal outcomes change over time; and 3) Assess
whether the effects of BCT messages on proximal outcomes a...

## Key facts

- **NIH application ID:** 10345627
- **Project number:** 1R01HL161373-01
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** CARMINA G VALLE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $769,818
- **Award type:** 1
- **Project period:** 2022-01-15 → 2025-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10345627

## Citation

> US National Institutes of Health, RePORTER application 10345627, A micro-randomized trial of JITAI messaging to improve adherence to multiple weight loss behaviors in young adults (1R01HL161373-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10345627. Licensed CC0.

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