Objective This living systematic review aims to provide a timely, rigorous and continuously updated summary about the impact of overweight or obesity as a prognostic factor for severity and mortality in patients with COVID-19. Design This is a protocol of a living systematic review. Data sources We will conduct searches in MEDLINE/PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), grey literature and in a centralized repository in L·OVE (Living OVerview of Evidence). L·OVE is a platform that maps PICO questions to evidence from Epistemonikos database. In response to the COVID-19 emergency, L·OVE was adapted to expand the range of evidence it covers and customised to group all COVID-19 evidence in one place. The search will cover the period until the day before submission to a journal. Eligibility criteria for selecting studies and methods We adapted an already published common protocol for multiple parallel systematic reviews to the specificities of this question. We will include all primary studies that assess patients with confirmed or suspected infection with SARS-CoV-2 and inform the relation of overweight or obesity with death or disease severity. Two reviewers will independently screen each study for eligibility, extract data, and assess the risk of bias. We will pool the results using meta-analysis and will apply the GRADE system to assess the certainty of the evidence for each outcome. A living, web-based version of this review will be openly available during the COVID-19 pandemic. We will resubmit it every time the conclusions change or whenever there are substantial updates.