To limit transmission of COVID-19, state governments issued shelter-in-place orders. These orders coincided with a decrease in daily step count and an increase in overeating. We evaluated factors associated with weight gain of ≥ 15 pounds during the pandemic within an integrated health care system.

We included adults ages 18 and above with at least one weight measurement before the pandemic (March 19, 2019–March 19, 2020) and another measurement after COVID-19 vaccines became available, more than 9 months into the pandemic (December 14, 2020–December 14, 2021). Logistic regression was used to identify factors associated with weight gain of 15 pounds or more.

Of 524,451 adults included in the study, median age was 61 years, 43.2% were men, 36.2% self identified as White, 8.6% Black, 35.7% Hispanic, and 16.2% Asian. During the pandemic, 38,213 (7.3%) adults gained ≥ 15 pounds. A higher proportion of young adults gained weight (16.2% age 18–39, 7.6% age 40–64, 4.7% age 65–79%, and 3.1% age ≥ 80). No significant difference was observed between men and women (7.2% men and 7.4% women). Weight gain was more prevalent among adults from low-income neighborhoods (8.9% low-income neighborhoods, 8.0% intermediate-income neighborhoods, and 6.5% high-income neighborhoods). Multivariable logistic regression demonstrated that compared to adults ages 65–79 years, young adults ages 18–39 years had the highest risk of gaining ≥ 15 pounds (adjusted OR 5.19, 95% CI 5.01–5.38). Black race was associated with weight gain in an unadjusted analysis (OR 1.25, 95% CI 1.21–1.30). However, this association was significantly attenuated after adjusting for other risk factors including neighborhood income levels (adjusted OR 1.06, 95% CI 1.02–1.10). Having a diagnosis of depression pre-pandemic was also associated with weight gain during the pandemic (adjusted OR 1.54, 95% CI 1.50–1.58).

In this racially and ethnically diverse population in southern California, significant weight gain of 15 pounds or more was observed in 7.3% of the adult population during the COVID-19 pandemic. Young adults, individuals who resided in low-income neighborhoods, and patients with depression were disproportionally affected.