The prevalence of overweight/obesity is rising in developing countries yet their effects on the Quality Of Life (QOL) of Nigerians have not been assessed. This study therefore investigated the prevalence of obesity determined by different tools and their effects on the QOL of young Nigerians. Internationally accepted protocols were employed for the anthropometric diagnosis of obesity while the percentage body fat was estimated using a bioelectrical impedance analysis device. The QOL of the subjects were assessed by subjective self-report. Appropriate statistical analyses were performed on the data generated. A total of 2000 young-adult Nigerians (50% females) were studied. The results show that a total of 17, 3.9, 0.4, 11.9 and 18% of the population were overweight/obese, when BMI, WC, WHpR, WHtR and percentage body fat, respectively, were used as diagnostic criteria. There was a clear female preponderance of obesity in the population. As much as 12.4% of the population were completely dissatisfied with their QOL and the QOL of the subjects was negatively affected by overweight/obesity irrespective of the diagnostic used. The QOL was worse in subjects with visceral obesity and very high percentage body fat compared to those with generalized obesity. Only the anthropometric measures of obesity were positively correlated with QOL in this population. The prevalence of overweight/obesity in this population is lower than previous reports from similar populations in Nigeria but not reports from outside Nigeria. The impact of obesity on QOL appears to be driven by the functional impairment and physical discomfort that arise from it.