Obesity as a Risk Factor for Severe COVID-19: Summary of the Best Evidence and Implications for Health Care

Abstract

Purpose of review: To collate the best evidence from several strands-epidemiological, genetic, comparison with historical data and mechanistic information-and ask whether obesity is an important causal and potentially modifiable risk factor for severe COVID-19 outcomes.

Recent findings: Several hundred studies provide powerful evidence that body mass index (BMI) is a strong linear risk factor for severe COVID-19 outcomes, with recent studies suggesting ~5-10% higher risk for COVID-19 hospitalisation per every kg/m² higher BMI. Genetic data concur with hazard ratios increasing by 14% per every kg/m² higher BMI. BMI to COVID-19 links differ markedly from prior BMI-infection associations and are further supported as likely causal by multiple biologically plausible pathways. Excess adiposity appears to be an important, modifiable risk factor for adverse COVID-19 outcomes across all ethnicities. The pandemic is also worsening obesity levels. It is imperative that medical systems worldwide meet this challenge by upscaling investments in obesity prevention and treatments.

Keywords: Activity; Body mass Index; Diet; Epidemiology; Genetics; Multimorbidity.

Fig. 1

Obesity and COVID-19. Evidence from multiple sources now links excess adiposity to risk for severe COVID-19 outcomes. Additionally, many conditions associated with adverse COVID-19 outcomes (e.g. type 2 diabetes, COPD) are also strongly linked to excess adiposity. At the same time, the pandemic and related lockdowns and changes in life circumstances are accelerating weight gain in many in the population. All of these facts means that governments around the world, and particularly in countries where obesity levels are already high, need to prioritise obesity prevention and management efforts. The consequences of not doing so will be high for both people and economies