Comparison of morning vs evening exercise on weight loss and related health behaviors in individuals with overweight or obesity: study protocol for a 56-week randomized controlled trial (TIMEX)
Year: 2025
Type: article
Study design: Study Protocol
Abstract: BACKGROUND: Aerobic exercise is recommended for weight management. Recent evidence suggests that there may be time-dependent differences in how exercise affects body weight and energy balance regulation. The primary purpose of this study is to determine the effect of morning versus evening aerobic exercise on changes in body composition and components of energy balance in adults with overweight and obesity. METHODS: The Timing Intervention of Morning versus Evening EXercise (TIMEX) study is a two-arm, 56-week, block randomized (1:1) aerobic exercise intervention. One hundred twenty-eight adults with overweight and obesity will be randomized to engage in morning (AM-Ex, 06:00-10:00) or evening (PM-Ex, 15:00-19:00) moderate- to-vigorous intensity aerobic exercise progressing to 2000 kcal/week of energy expenditure. The primary outcome is change in body weight at 7 months. Secondary outcomes include changes in body composition, energy intake, hunger and eating behaviors, energy expenditure, and physical activity behaviors at 7 and 13 months. DISCUSSION: Aerobic exercise elicits modest weight loss; however, there is substantial inter-individual variability in the weight loss response with some individuals losing significant amounts of weight and others gaining weight. The time of day exercise is performed may contribute to this weight loss variability. Understanding how the time of day of exercise affects weight loss and components of energy balance may lead to tailored exercise interventions that enhance weight loss. The TIMEX study will determine the effect of a guidelines-based dose of aerobic exercise completed in the morning versus the evening on weight loss, energy intake, and energy expenditure. TRIAL REGISTRATION: ClinicalTrials.gov NCT02153252. Registered on 12/10/2021.
Source: Trials
Language: English
Topic: Physical Activity and Health
Subfield: Physiology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,790
Awards: G1143439577, G1625418467, G2360802214, G5228838840, Linking temporal patterns of modifiable behaviors to weight loss outcomes, G7109870612, Designing with dissemination in mind: Development and evaluation of a theory-based physical activity intervention using the Multiphase Optimization Strategy, Colorado Clinical and Translational Sciences Institute (CCTSI), Does When You Exercise Matter? A Randomized Trial Comparing the Effect of Morning versus Evening Aerobic Exercise on Weight Loss and Compensatory Behaviors
OpenAlex ID: W4417304272