Introduction. Obesity, defined as an excess of body fat causing prejudice to health, is a major risk factor for adverse outcomes after infection with SARS-CoV-2. The purpose of this study aimed to provide evidence of the relationship between obesity and clinical outcomes in young patients with COVID-19. Material and methods. A literature search for various terms such as “obesity”, “overweight”, “young” and “SARS-CoV-2” was conducted. A total of 13 articles were eligible. Extracted data included anthropometric and metabolic parameters such as fasting glycaemia, lipids, liver function and renal function. Results. Assessment of excess body weight among the study population showed that the severe group with COVID-19 had a higher BMI and an increased risk of mortality (class I obesity compared with class III, P<0.0001; class II compared with class III, P=0.008). Evaluation of metabolic indices showed that patients with severe forms had higher fasting glucose, although patients have no previous history of diabetes, higher level of low-density lipoprotein cholesterol and a lower level of high-density lipoprotein cholesterol compared with moderate cases (all P < 0.01). The liver function was more affected in severe group, with higher ALT and AST compared with patients with moderate cases (all P < 0.01). Regarding renal function, the severe group had higher levels of creatinine (84.40 vs. 60.90 μmol/L), uric acid (398.75 vs.293.35 μmol/L) compared with the moderate group. Conclusions. We found a significant positive linear association between increasing BMI and outcomes in young patients with COVID-19.