Low birth weight and a rapid weight gain in early childhood may lead to an increased risk for developing cardiovascular disease later in life, such as hypertension and dyslipidaemia. In this study, we examined the associations between size at birth, relative weight gain in infancy and childhood with specific cardiovascular disease risk factors in early adulthood. Adolescents (n=1935) from the Birth to Twenty plus (BT20+) cohort were included in the analysis. The following were treated as exposure variables: weight at birth, and relative conditional weight gain (CW), independent of height, between ages 0–24 months and 24–48 months. Outcomes were serum lipids and body composition variables at age 18 years. After adjusting for sex and other confounders, early life exposures were not associated with adolescent lipid profile. Following adjustment for sex and height (body size), birth weight [β=0.704 (0.40, 1.01)], CW 0–24 [β=1.918 (1.56, 2.28)] and CW24–48 [β=1.485 (1.14, 1.82)] accounted for 48% of the variance in fat mass. However, birth weight [β=0.773 (0.54, 1.01)], CW 0–24 [β=1.523 (1.24, 1.80)] and CW24–48 [β=1.226 (0.97, 1.49)] were also positively predicted and accounted for 71% of the variance in fat mass in adolescence (P<0.05). Our data suggests that birth weight and weight gain during infancy and early childhood independent of linear growth are related to adolescent body composition but not blood lipid profiles in an urban African population.