Reminder Strategies to Improve Meal-Logging Adherence

April 28, 2026 updated by: University of St.Gallen

This study is a single-center micro-randomized trial, aiming to examine the effects of two theory-driven reminder strategies on adherence to repeated, image-based meal logging in adults age 45 and older. Three times daily, participants are automatically randomized to receive one of three reminder messages prior to each habitual mealtime. The main research questions the trial aims to answer are:

  • Do loss-framed reminders (emphasizing loss of a daily financial reward for not logging) increase meal logging adherence in the two hours following a reminder, compared to a neutral reminder?
  • Do logging consistency reminders (providing feedback on recent logging streaks) increase meal logging adherence in the two hours following a reminder, compared to a neutral reminder?
  • Do the effects of loss-framed and logging consistency reminders differ from each other?

Primary aim: To estimate the proximal effect of each reminder type on whether a participant logs a meal within two hours of receiving a reminder.

Secondary aim: To examine whether within-person physiological patterns (e.g., heart rate variation) moderate response to reminders, with the goal of identifying physiological markers of receptivity to behavioral prompts.

The trial aims to enroll 200 adults aged 45 and older. Participants attend a baseline visit for onboarding, consent, and device setup, followed by a 28 day remote intervention period during which they should photograph their meals three times daily (breakfast, lunch, dinner) and wear a smartwatch and smart ring continuously. Prior to each mealtime, they receive an automatically randomized reminder message. Participants earn a daily financial reward contingent on completing meal logging for that day.

Note: This trial was registered retrospectively as enrollment began prior to registration. However, registration was completed before data collection was finished and before any data analysis was conducted.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

200

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Switzerland
    • Canton of St. Gallen
      • Sankt Gallen, Canton of St. Gallen, Switzerland, 9000
        • Recruiting
        • HOCH Health and School of Medicine, University of St. Gallen
        • Contact:
        • Principal Investigator:
          • Mia Jovanova, Dr.
        • Principal Investigator:
          • Tobias Kowatsch, Prof.Dr.
        • Principal Investigator:
          • Michael Brändle, Prof.Dr.med

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Citizens or residents of Switzerland who are German-speaking (main place of living or employment in Switzerland).
  • Age ≥45 years.
  • BMI ≥25 kg/m² (overweight or obese).
  • Regular access to a smartphone (iOS or Android) with a data plan.
  • Able to use smartphone applications.
  • Able to walk independently.

Exclusion Criteria:

  • History of stroke, heart disease, renal failure, cancer, or diabetes (type 1 or type 2).
  • Past vascular bypass surgery or angioplasty.
  • Current or planned use of glucose-lowering medications during the upcoming 4 weeks (e.g., GLP-1 receptor agonists, metformin).
  • Pregnant or breastfeeding.
  • Relevant skin conditions at wearable placement sites (e.g., upper arm).
  • BMI <25 kg/m² confirmed at enrollment.
  • FPG ≥7.0 mmol/L and/or HbA1c ≥6.5% (newly identified type 2 diabetes); Individuals who meet type-2 diabetes criteria at enrollment, based on Swiss/ADA diagnostic criteria will be informed of blood test results and referred to a GP. These individuals will be deemed ineligible and excluded from the study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Loss-Framed Reminder
A push notification emphasizing the loss of a daily financial reward for not logging the upcoming meal. Assigned with 1/3 probability at each decision point.
Behavioral: Loss-Framed Reminder
Push notification emphasizing loss of daily financial reward for not logging the upcoming meal.
Experimental: Logging Consistency Reminder
A push notification providing feedback on the participant's recent meal logging streak. Assigned with 1/3 probability at each decision point.
Behavioral: Logging Consistency Reminder
Push notification providing feedback on recent meal logging streak.
Active Comparator: Neutral Reminder (Active Control)
A push notification reminding the participant to log a meal without loss-framing or consistency feedback. Serves as the reference condition against which the two experimental reminders are compared. Assigned with 1/3 probability at each decision point.
Behavioral: Neutral Reminder
Push notification reminding participants to log a meal.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Meal Logging Adherence
Time Frame: Within 2 hours of each decision point, assessed over 28 days
Proportion of decision points at which a participant logs a meal within 2 hours of receiving a reminder, compared across reminder types (loss-framed, logging consistency, and neutral control).
Within 2 hours of each decision point, assessed over 28 days

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Moderators of Reminder Responsiveness
Time Frame: Assessed over 28 days
Meal logging adherence (binary, within 2 hours of a decision point) examined as a function of participant-level moderators including physiological (e.g., heart rate variability), demographic (e.g., age, sex), and behavioral characteristics, to identify moderators of differential responsiveness to reminder types.
Assessed over 28 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of St.Gallen

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 8, 2025

Primary Completion (Estimated)

January 1, 2027

Study Completion (Estimated)

January 1, 2027

Study Registration Dates

First Submitted

April 21, 2026

First Submitted That Met QC Criteria

April 21, 2026

First Posted (Actual)

April 29, 2026

Study Record Updates

Last Update Posted (Actual)

May 5, 2026

Last Update Submitted That Met QC Criteria

April 28, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • GLOWUP-MRT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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