The present and future implication of academic performance of learners at all levels has made it a public health concern. Poor diet quality and overall health status of adolescents are among the prominent factors implicated for poor academic performance among adolescents. In Nigeria, poor health status and low level of academic performance have been reported among in-school adolescents. A report of the Federal ministry of health showed that almost a third of young people in both primary and secondary schools in Nigeria are undernourished while 9% are over nourished. With regards to academic performance, findings have shown that low level of academic performance is common among in-school adolescents. The rationale for this study was based on the fact that while much work had been done on the influence of factors such as school type and location, parental involvement, family structure and sex on academic performance of in- school adolescents, little or none has been done in assessing the relationship between dietary pattern and body mass index on academic performance among in-school adolescents. This study thus tried to bridge this gap.