Circulating fasting total BA was not associated with obesity .
FGF19 was inversely and faecal BA excretion was positively associated with obesity .
Roux-en-Y gastric bypass ( RYGB ) and sleeve gastrectomy ( SG )  modulated BA metabolism , ie , increased BA and FGF19 .
Our results indicate that BA metabolism is altered in obesity .
Cholesterol saturation of bile after jejunoileal bypass increases more with a 1:3 than with a 3:1 jejunoileal ratio.
Previous suggested , surprisingly , that after jejunoileal bypass surgery the lithogenicity of the bile , assessed by its cholesterol saturation and rate of gallstone formation , increases more with a 1:3 than with a 3:1 jejunoileal ratio of the functioning segment . The present study re-evaluates this by examining fasting bile sample s drawn from duodenum after cholecystokinin stimulation in 34 obese patients without gallstones , who either were waiting for or had had bypass surgery , with a 1:3 or 3:1 jejunoileal ratio , 3,9 , or 15 months earlier . In all groups , the cholesterol content exceeded the solubilizing capacity of the bile as determined on the basis of total lipid concentration and content of phospholipid relative to bile acids . The cholesterol supersaturation increased with bypass surgery as such , increased more with a 1:3 than with a 3:1 jejunoileal ratio , decreased with time after surgery , and reached the preoperative level at 15 months . Assuming a total lipid concentration of 10 g/dl in the bile did not change this pattern . Our results indicate that during the period of weight loss after bypass surgery the lithogenicity of gallbladder bile increases more with a 1:3 than with a 3:1 jejunoileal ratio
Circulating fasting total BA was not associated with obesity .
FGF19 was inversely and faecal BA excretion was positively associated with obesity .
Roux-en-Y gastric bypass ( RYGB ) and sleeve gastrectomy ( SG )  modulated BA metabolism , ie , increased BA and FGF19 .
Our results indicate that BA metabolism is altered in obesity .