Review of Obesity Paradox

Abstract

Introduction: Obesity is a risk factor for many health conditions and complications but may be regarded as a prognostic factor in other conditions. This has been described as the "obesity paradox." The debate whether this paradox exists across all health conditions is a hot topic of research, which is why this review aims at systematically analyzing reviews on the obesity paradox to explore where it holds true and help guide further research and clinical implications. Methods: PubMed was searched using the key term "obesity paradox" with a systematic review and meta-analysis filter with no restriction on the date. Results: A total of 40 reviews were included. Most of the reviews included observational cohort studies focusing on various health conditions such as cancer, atrial fibrillation, stroke, heart failure, acute coronary events, dialysis, chronic diseases, surgery, etc. The obesity paradox appeared to exist in all reviewed health conditions except for solid tumors, where there was no obesity paradox regarding mortality or treatment toxicities. The obesity paradox relationship, however, was not homogeneous across the health systems, and the relationships were described as linear, U-shaped, or J-shaped (the latter two being the most common). Conclusions: The relationship between obesity and health outcomes is not straightforward as obesity is sometimes a risk factor for worse outcomes and other times associated with improved mortality. Hence, there is a need for randomized controlled trials to validate why and in which diseases the obesity paradox exists and understand its pathophysiology. Meanwhile, patients with obesity remain a challenge in the clinical context and need special attention to address their obesity and control their risk factors.