Associations between body mass index/fat mass index and activity levels as tested both by conventional epidemiological approaches and through the application of instrumental variable analysis using a 31-SNP weighted allelic score (excluding <i>FTO</i>) as an instrument.

<p>Regression results were adjusted for age.</p>a<p>Coefficients are displayed as sex-specific <i>z</i>-scores for both measures of adiposity and activity levels and have been rescaled to give more meaningful outcomes relating to the raw units of these variables. The raw-unit difference was computed by multiplying the <i>z</i>-score value by the SD of the variable, taken from <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1001618#pmed-1001618-t001" target="_blank">Table 1</a>.</p>b<p><i>p</i>(DWH) is the <i>p</i>-value of the Durbin form of the DWH test, which examines the difference between the estimates from linear regression and instrumental variable analysis.</p>c<p>Moderate-to-vigorous activity was log transformed for analysis.