Yao, Zhiqi, Tchang, Beverly G, Chae, Kacey et al. · Journal of internal medicine · 2025 · DOI
This study looked at over 323,000 people in the United States to understand how obesity affects overall health and quality of life. Researchers found that people with higher body weight reported worse health, more pain, more fatigue, and greater difficulty with physical activity compared to people of normal weight. The effects were strongest in people with the most severe obesity, who were nearly 4 times more likely to report poor health and severe pain.
This study is relevant to ME/CFS patients and researchers because it examines the relationship between obesity and fatigue, pain, and functional limitation—symptoms that overlap significantly with ME/CFS. Understanding how obesity influences these symptom domains may help clinicians and patients better characterize disease burden and distinguish between obesity-related fatigue versus ME/CFS-related fatigue in clinical practice.
This study does not prove that obesity causes ME/CFS or chronic fatigue syndrome; it only demonstrates statistical associations in a cross-sectional design. The study cannot establish causality or the direction of the relationship—it is possible that underlying illness (including undiagnosed ME/CFS) leads to weight gain rather than obesity causing fatigue. Additionally, the study's self-reported outcome measures were not validated against objective biomarkers or clinical assessment criteria specific to ME/CFS.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Yao, Zhiqi, Tchang, Beverly G, Chae, Kacey, Albert, Michael, Clark, Jeanne M, & Blaha, Michael J (2025). Adverse effects of obesity on overall health, quality of life, and related physical health metrics: A cross-sectional and longitudinal study from the All of Us Research Program.. Journal of internal medicine. https://doi.org/10.1111/joim.20083
BibTeX
@article{mecfsatlas-yao-2025-adverse-effects,
author = {Yao, Zhiqi and Tchang, Beverly G and Chae, Kacey and Albert, Michael and Clark, Jeanne M and Blaha, Michael J},
title = {Adverse effects of obesity on overall health, quality of life, and related physical health metrics: A cross-sectional and longitudinal study from the All of Us Research Program.},
journal = {Journal of internal medicine},
year = {2025},
doi = {10.1111/joim.20083},
note = {PubMed: 40325914},
url = {https://www.mecfsatlas.com/evidence/yao-2025-adverse-effects},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/yao-2025-adverse-effects
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