The Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that was most recently discovered, quickly evolved into a global pandemic. Studies suggested that obesity was a major risk factor for its hospitalization and severity of symptoms. This study investigated the associations between obesity prevalence with overall COVID-19 cases and related deaths across states in the United States. General regression and Chi-square tests were used to examine those associations. The analyses indicated that obesity prevalence (%) across states were negatively associated with COVID-19 cases (p = 0.0448) and related deaths (p = 0.0181), with a decrease of 158 cases/100K population and 13 deaths/100K for every 5% increase of the obesity prevalence. When the states were divided based on the median of obesity prevalence (30.9%) into a group of states with low obesity prevalence and a group with high obesity prevalence, both the cases (671 vs 416 cases/100k population) and deaths (39 vs 21 deaths/100k population) were significantly different (p < 0.001) across groups. These findings provided important information for the relationship between the dual pandemic threats of obesity and COVID-19. These results should not currently be considered as an indication that obesity is a protective factor for COVID-19, and would rather be used as a warning of the public advice that obese people is more vulnerable to COVID-19 infection, which may lead to a false safety message probably given to people with normal body weight.