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Original Article

Associations of routine breakfast and napping habits with early adiposity rebound by age 3 years: a populationbased cohort study in Japan

Toshifumi Yodoshi^1,2 

¹Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children’s Hospital Medical Center, Cincinnati, USA;
²Department of Clinical Research and Quality Management, Center of Clinical Research and Quality Management, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan

Correspondence Toshifumi Yodoshi ,Email: Toshifumi.Yodoshi@cchmc.org

Received: August 26, 2025; Revised: September 1, 2025   Accepted: September 2, 2025.

Abstract

Background
Early adiposity rebound (AR) is a key predictor of later obesity and metabolic risk, yet modifiable factors related to early AR remain understudied in large populations.
Purpose
To quantify the prevalence of early AR at age 3 years and identify modifiable correlates in a population‑based cohort of Japanese preschool children.
Methods
We retrospectively analyzed health-check records for 74,466 children who attended both 1.5- and 3-year examinations (2014–2019). Body mass index (BMI) values were converted to World Health Organization z scores; early AR was defined as any increase in BMI between 1.5 and 3 years. Multivariable logistic regression adjusted for birth weight category, sex, household structure, sleep duration, and behavioral factors.
Results
Early AR occurred in 18,673 children (25%), whereas obesity (BMI z score ≥1.64) was present in 4% at 3 years. After controlling the adjustments, routine breakfast consumption (odds ratio [OR] 0.88; 95% confidence interval [CI], 0.81–0.97) and regular napping at 1.5 years (OR, 0.84; 95% CI, 0.79–0.90) were independently associated with reduced odds of early AR, while obesity at 1.5 years strongly predicted early AR (OR, 4.32; 95% CI, 4.00–4.67). Routine juice intake or fast-food consumption showed no significant associations.
Conclusion
In this population‑based cohort, one in 4 preschoolers had early AR by age 3. Simple daily routines— eating breakfast and maintaining regular sleep— may help delay AR and offer actionable targets for early obesity prevention.

Keywords :Adiposity rebound, Pediatric obesity, Body mass index, Child, Preschool