Whether energy balance during early life and/or adulthood is related to glioma risk is unknown. We therefore investigated height, body mass index (BMI), and physical activity in relation to glioma risk in the prospective NIH-AARP Diet and Health Study. Participants completed a baseline questionnaire (sent in 1995-1996) inquiring about height, weight, and potential confounders. A second questionnaire (sent in 1996) inquired about physical activity during ages 15 to 18, 19 to 29, and 35 to 39 years and the past 10 years and body weight at ages 18, 35, and 50 years. During follow-up from 1995/1996 to 2003, we documented 480 cases of glioma among 499,437 respondents to the baseline questionnaire and 257 cases among 305,681 respondents to the second questionnaire. Glioma risk among tall persons (>or=1.90 m) was twice that of short persons [<1.60 m; multivariate relative risk (RR), 2.12; 95% confidence interval (95% CI), 1.18-3.81; P(trend) = 0.006]. Risk among participants who were obese (BMI 30.0-34.9 kg/m(2)) at age 18 years was nearly four times that of persons of normal weight (BMI 18.5-24.9 kg/m(2)) at age 18 years (RR, 3.74; 95% CI, 2.03-6.90; P(trend) = 0.003); 11 cases were obese at age 18 years. Risk among participants who were active during ages 15 to 18 years was 36% lower than that of persons who were inactive during ages 15 to 18 years (RR, 0.64; 95% CI, 0.44-0.93; P(trend) = 0.02). BMI and physical activity after age 18 years were unrelated to glioma risk. Adult height, BMI during adolescence, and physical activity during adolescence were each associated with glioma risk, supporting a role for early-life energy balance in glioma carcinogenesis.