The effect sizes attributable to the associated variants range from 0.06 to 0.33 BMI units per allele, and each explains only a small proportion of the variance in adult BMI. As might be expected, given these modest effects and the smaller size of the relevant available datasets, we did not consistently observe measurable effects on the risk of diseases in which obesity is one of several contributing factors (such as type 2 diabetes). It is also possible that some of these variants influence BMI but have negligible effects on the downstream risk of obesity-related disease. Despite these small effects on BMI, when we combined information from the eight validated loci, we were able to identify small groups of individuals who differ appreciably with respect to mean BMI. However, at the population level, the value of these signals in predicting obesity remains quite limited (Supplementary Fig. 4 online).
