August 14, 2020

Obesity increases risk of death from COVID-19

Kaiser Permanente study found risk of death from COVID-19 for those who are obese is higher for men and young people.

Contact: Terry Kanakri

Kerry Sinclair

PASADENA, Calif. — In a study published in Annals of Internal Medicine, Kaiser Permanente research shows that obesity was associated with a substantial increased risk of death from COVID-19. However, it also found that the risk of death from COVID-19 associated with obesity is not uniform among those who are obese, but instead disproportionately affects men and people under 60 years of age.

“Although this study examines a variety of factors that may be associated with risk of death from COVID-19, our main objective in this paper was to understand risk related to obesity, and obesity-associated chronic conditions in our health care system,” said lead researcher, Sara Y. Tartof, PhD, MPH, of Kaiser Permanente Southern California Department of Research & Evaluation.

In this study, researchers looked at the electronic health records of 6,916 Kaiser Permanente Southern California members who tested positive for COVID-19 between February 13, 2020, and May 2, 2020. The mean age of the patients was 49 years and mean body mass index, or BMI, was 30.5. A BMI of 30 to 39 is considered obese, 40 to 44 is severely obese, and 45 or higher is extremely obese.

Among the findings:

  • Patients who were severely obese had nearly 3 times the risk of death and those who were extremely obese had over 4 times the risk of death from COVID-19 compared to those of normal weight.
  • Severely and extremely obese people who were 60 years old and younger had a substantially higher risk of death than severely obese people over age 60.
  • Severely and extremely obese men had a very high risk of death, while women had no increased risk of death associated with obesity. searchers were able to control for a variety of risks previously reported in the literature and did not detect increased risk of death from COVID-19 associated with Black or Latinx race/ethnicity alone.

“Our findings suggest that it is not race or ethnicity alone that increases risk of death, but rather other correlated factors, including access to health care, comorbidities, and obesity, that also play an important role,” Dr. Tartof said.

Sara Y. Tartof, PhD, MPH
Sara Y. Tartof, PhD, MPH

She explained that the findings provide more insight into disparities in severity of COVID-19 among minority communities. Having access to a diversity of health information allows researchers to begin to disentangle the factors that may contribute to these disparities, she said.

“At Kaiser Permanente, we have the ability to see what happens when patients from different race, ethnic, and socioeconomic backgrounds have better access to high quality of care,” she said. “When we even out access, and tease apart health factors that are often related, we can have a better picture of the role of race/ethnicity alone.”

Sameer B. Murali, MD, an internal medicine physician at Kaiser Permanente Fontana Medical Center and senior author on this study, noted that when physicians know more precisely who is at elevated risk of death, they can put in place treatment plans and interventions to modify that risk, rather than treating every patient the same.

“By viewing the risk posed by obesity through the prism of COVID-19, this study advances the characterization of obesity as a disease that demands a public health and clinical response similar to that for diabetes or heart disease,” he said. “One pandemic is expanding our understanding of another, and we hope this work not only provides physicians and patients a better grasp of the risk obesity poses in the setting of COVID19, but also to overall health.”

Dr. Tartof noted that this study supports new hypotheses about what drives the overactive immunological response to COVID-19 that can lead to death, and opens new pathways of research. 

Other coauthors on this study were: Lei Qian, PhD, MS; Vennis Hong, MPH; Rong Wei, MA; Susan L. Caparosa, MA; Claudia L. Nau, PhD; Heidi Fischer, PhD, MS; Kris Li, MS; Sally F. Shaw, DrPH, MPH; and Adam L. Sharp, MD, MSc, of the Kaiser Permanente Department of Research & Evaluation; Ron F. Nadjafi, MD, MS, Kaiser Permanente Southern California Clinical Informatics, Pasadena; Gunter K. Rieg, MD, and Bradley K. Ackerson, MD, Southern California Permanente Medical Group, Harbor City, Calif.; Jacek Skarbinski, MD, The Permanente Medical Group, Oakland, Calif.; Tej K. Naik, MD, Southern California Permanente Medical Group, Ontario, Calif.; and Tanmai Saxena, MD, PhD, Southern California Permanente Medical Group, Anaheim, Calif.

About the Kaiser Permanente Southern California Department of Research & Evaluation

The Department of Research & Evaluation conducts high-quality, innovative research into disease etiology, prevention, treatment, and care delivery. Investigators conduct epidemiologic research, health services research, biostatistics research, and behavioral research as well as clinical trials. Major areas of study include chronic disease, infectious disease, cancer, drug safety and effectiveness, and maternal and child health. Headquartered in Pasadena, California, the department focuses on translating research to practice quickly to benefit the health and lives of Kaiser Permanente Southern California members and the general public. Visit

About Kaiser Permanente

For 75 years, Kaiser Permanente has been committed to shaping the future of health and health care — and helping our members, patients, and communities experience more healthy years. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Since July 21, 1945, Kaiser Permanente’s mission has been to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve 12.4 million members in 8 states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal Permanente Medical Group physicians, specialists, and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery, and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education, and the support of community health.