Yes, the degree of malabsorption will also depend on how much small intestine you have had bypassed, so a longer bypass = greater malabsorption. Incidentally, the bypass has a big effect on fat malabsorption (hence why eating a high fat meal can make you dump), and this is why we need to take vitamin supplements post-op. Many vitamins are fat soluble, meaning fat is needed to be absorbed through the small intestine for vitamins to also be absorbed. Another interesting snippet of information I read in a journal article the other day, is that carbohydrate absorption is least affected by our bypasses...hence the nedd to try to keep to low GI carbs as we still continue to absorb calories from carb-dense rich foods easily.