At T2 , after the diet switch , the `` control '' group showed a further reduction in GIS score ( 2.7 1.9 , -44.9 % , P = 0.01 ) , while the `` true '' group did not ( 2.6 1.8 , -21.3 % , P = 0.19 ) , so that the GIS scores did n't differ between the two groups .