Background and aims: Few studies distinguished the independent role of overweight/obesity or their associated-comorbidities in the evolution towards severe forms of COVID-19. Obesity as a unifying risk factor for severe COVID-19 is an emerging hypothesis. The aim of this study was to evaluate whether excessive body weight per se, was a risk factor for developing a severe form of COVID-19. Patients and methods: We included 131 patients hospitalized for COVID-19 pneumonia in a single center of the internal medicine department in Marseille, France. We recorded anthropometric and metabolic parameters such as fasting glycaemia, insulinemia, HOMA-IR, lipids, and all clinical criteria linked to SARS-CoV-2 infection at the admission. Excess body weight was defined by a BMI ≥ 25 kg/m2. The occurrence of a serious event was defined as a high-debit oxygen requirement over 6 L/min, admission into the intensive care unit, or death. Results: Among 113 patients, two thirds (n = 76, 67%) had an excess body weight. The number of serious events was significantly higher in excess body weight patients compared to normal weight patients (respectively 25% vs 8%, p = 0.03) although excess body weight patients were younger (respectively 63.6 vs 70.3 years old, p = 0.01). In multivariate analyses, the excess body weight status was the only predictor for developing a serious event linked to SARS-CoV-2 infection, with an odds ratio at 5.6 (95% CI: 1.30-23.96; p = 0.02), independently of previous obesity associated comorbidities. There was a trend towards a positive association between the BMI (normal weight, overweight and obesity) and the risk of serious events linked to COVID-19, with a marked increase from 8.1% to 20% and 30.6% respectively (p = 0.05). Conclusion: Excess body weight was significantly associated with severe forms of the disease, independently of its classical associated comorbidities. Physicians and specialists in Public Health must be sensitized to better protect people with an excess body weight against SARS-CoV-2 infection.