We prospectively investigated the relationship between adiposity-related measures with lung cancer incidence in a large cohort of never-smokers. In contrast to previously reported results from prospective cohort studies of smokers, we observed no evidence for an inverse association between adulthood/middle age obesity and subsequent lung cancer risk. If anything, an obese BMI at baseline was positively associated with lung cancer, although this association was not statistically significant. We also observed some evidence that having an overweight BMI at age 18 was positively associated with lung cancer risk. Positive associations were observed with higher waist circumference and more time spent sitting; whereas hip circumference appeared to be inversely associated with lung cancer. No statistically significant associations were observed with waist-hip-ratio or vigorous physical activity.