The overall prevalence of overweight/obesity among the adolescents was 10.2%. This prevalence is higher than the country specific estimate, the regional estimate for West Africa and the global estimate by the joint child malnutrition estimates by WHO and UNICEF . This prevalence is however similar to the 13.85% reported by the global burden of disease project . Disparities also exist among studies carried out in Nigeria. While few of the recent studies in Nigeria have reported low prevalence of overweight/obesity [20, 21], more of the recent studies are reporting rates similar or even higher than the 10.2% found in this study [10, 11, 15, 22, 23]. Having a national perspective on the prevalence of obesity in Nigeria has been challenging, especially because different studies have used differing methodologies and reference values . It can however be agreed that the prevalence of overweight/obesity is rising among adolescents in Nigeria. The overall prevalence of underweight in this same adolescent population was 12.1%. This typifies the double burden of disease, which is the paradoxical co-existence of under- and over-nutrition, which in this case is occurring at the population level [3, 25].
The significantly associated independent factors for the nutritional status of the respondents were gender and maternal occupation, such that females and children of professional mothers were more likely to be overweight/obese compared to the others. The association of gender, especially the female, has been similarly reported by previous similar studies. The effect of socio-economic and wealth status of the family and childhood obesity has been well documented. The finding in this study further goes to show that the socio-economic or wealth status of the mother may be what is really responsible. This may be understandable because of the usual bond/closeness of mothers and their children. Although there was marked difference in the prevalence of nutritional status across the different ages, with 20% at 10 years, 17% at 13 and 0% at 19%, these differences were however not statistically significant as was reported by other studies. This may be due to the number of respondents recruited in the different ages.
The low prevalence of glucose intolerance may be the reason why it did not show significant associations. It may not also be unrelated with the relatively small sample size of those who consented to take the test. Another possible reason may be a slower or more prolonged pathophysiology of glucose intolerance.
The prevalence of systolic and diastolic pre-hypertension was 10.9 and 11.5% respectively, while the prevalence for systolic and diastolic hypertension were 14.4 and 8.6% respectively. Overall, 32.9% had one form of elevated blood pressure or another. Similar findings, but with higher prevalence of pre-hypertension have been reported by Ejike et al.  in Nigeria, and Nkeh-Chungag et al.  in South Africa who reported (23.6 and 11.05%) and (21.2 and 12.3%) respectively, for prevalence of pre-hypertension and hypertension. A much lower prevalence was reported by Omisore et al.  in a similar study also carried out in southwestern Nigeria. This may however be due to the fact that they used a different methodology for classifying pre-hypertension and hypertension among the adolescents. This rising prevalence of elevated blood pressure should be a thing of concern among stakeholders for adolescent health in Nigeria. This finding corroborates the report of the global disease burden where the prevalence of non-communicable diseases among adolescents was put at 7.7%, similar to what was reported in some wealthy countries like United States of America, Spain and China . The predictors of elevated blood pressure among the adolescents were female gender, alcohol intake, overweight/obesity and risk for metabolic disease as measured by WHtR.
The risk for cardio-metabolic diseases was 7.3%, as assessed by WHtR which has been found to be the best predictor of cardio-metabolic risk and mortality [12, 27], and has been used by similar studies . To the best of our knowledge, this is the first study that assessed cardio-metabolic risk among adolescents using WHtR in Nigeria, hence no comparisons could be made within Nigeria. The proportion of adolescents with cardio-metabolic risk using WHtR in this study is low compared to the proportion in a large sample study in China. This difference is understandable since the two countries are socio-economically different, and the particular study reported overweight/obesity rates more than twice the prevalence found in this study. However, the findings of this study similarly show associations between indicators of nutritional status (BMI), WHtR and elevated blood pressure . BMI and WHtR had significant positive correlation with SBP and DBP, and WHtR had the strongest, significant positive correlation with BMI. The proportion of those with elevated BP among overweight/obese were more than double the proportion among those with normal BMI. The proportion with high WHtR increased nearly 16 times among those with normal BMI to those overweight/obese. Another graphic representation of this relationship was the fact that half of those overweight/obese had high WHtR, while none of those underweight had high WHtR. These findings corroborates the need for monitoring of the nutritional status and cardio-metabolic risk or diseases even among adolescents .
The limitations of this study may include the fact that the respondents in this study were secondary school-attending adolescents in an urban community in southwestern Nigeria, generalization should therefore be done cautiously. There were only 4 respondents for age 19 and only 14 for age 18, because many of the age 18 and 19 would have left secondary school. There were relatively fewer respondents for the younger ages because of poor cooperation from them. Only 179 of the respondents consented to random glucose check, mainly for fear of needle prick, and majority did not agree to an overnight fast for fasting blood sugar.
Measurement of BP using oscilliometric devices and also on a single visit may tend to over-estimate the prevalence, and it may not be appropriate for diagnostic purposes. However, it was appropriate for the objectives of this study which was not for diagnostic nor individual interpretation rather, it was more like a screening at population level. Hence, the terms elevated blood pressure were the prominent terminology.