During childhood, excessive weight is negatively associated with the development of motor skills, with children with overweight or obesity having poorer motor skills compared to children with normal weight. The objectives of the current study are to identify the differences in motor skills between children and adolescent with obesity and severe obesity and the extent of this difference. To do so, we examined cross-sectionally 165 subjects. Physical fitness was analyzed in both participants with obesity (>97th-99.9th BMI percentile) and severe obesity (>99.9th BMI percentile) using eight standardized tests: sit-and-reach, grip force, sit-ups, push-ups, balance, hand-eye coordination, standing long jump and 5-meter shuttle run. Poorer performance were observed in participants with severe obesity in sit-ups (children: 59%; 18.6±17.0 percentile value vs. 29.5±23.2 percentile value, p=0.008), balance (adolescent: 59%; 12.1±12.2 sec. v. 19.3±13.9 sec., p=0.034) and in the 5-meter shuttle run (children: 49%; 14.0±13.9 percentile value vs. 20.8 ± 19.4 percentile value, p=0.046; adolescents: 11%; 13.2±2.2 sec. vs. 11.8±1.6 sec., p=0.008) compared to obese counterparts. In conclusion, while physical performance was found to be similar between the different obesity levels for the majority of tests, youth with severe obesity demonstrated impairments ranging from 11 to 59% in specific tests.