Question:
Does bypass surgery prevent fat absorption?

I read that after bypass surgery there is no fat absorption. Does anyone have any info on this?    — clara M. (posted on November 19, 2000)

November 18, 2000
Good question Clara, and I'm curious as to how much fat we absorb after WLS as well. I know you'll get answers saying that it depends on the type of surgery and whether it was proximal, medial or distal. But from my own experience and the post-op diet I was given, we are not encouraged to (nor can some tolerate), consume large amount of fats. My limit as suggested by my nutritionist is 29-42 grams a day. I remember one of my pre-op low fat diets was to stay under 30 grams a day to lose weight. Also, we must have some fat in our diet in order for our cells to operate properly - although apparently not much. And there have been more than a few WLSers that have blown their gallbladders after surgery because of the low fat diets. I assume if we didn't absorb fat at all, that we would be told to increase it or supplement as we do protien. I'll be waiting for more educated answers with you!
   — Allie B.

November 19, 2000
CLARA MADISON: Hello! I think you are referring to the BPD/DS procedure. This surgery involves 'sleeve gastrectomy (SP?)' in that the stomach is permanantly made smaller by removing most of the fundus, or storage/acid producing area. The cut is made lengthwise, so the stomach retains functionality and shape - it is just made smaller. The pyloric valve is left intact, so food is stopped and processed in the smaller stomach (it is larger than the RNY/Fobi pouch but much smaller than pre-surgically) then released into a short section of the duodenum (the first segment of small intestines, which is bypassed in the RNY). From here, two 'limbs' are formed: One carries food to the lowest part of the small intestine ('the common channel) and the other carries bile/pancreatic juices to this area. The food cannot be absorbed without the juices, so this bypass is a distal one in that food is absorbed in the small bit of duodenum and then in standard 100 cm (or slightly more) of common channel before the colon. Since a portion of this area (where fats are absorbed) is bypassed, patients with BPD/DS are unable to retain a majority of fat that is consumed. This means that one must be strict about daily supplements (especially the fat soluable vitamins - ADEK). If the supplements are adhered to and the patient does get the recommended follow up care, he/she is not likely to experience serious nutritional deficiencies from the procedure. Such deficiencies take time to develop and can be corrected early with proper aftercare and/or avoided/minimized with proper supplementation and nutrition. On another positive note, research has shown that the body naturally tries to compensate for the bypassed areas and develops more receptors, elongates and becomes thicker in the common tract where absorption occurs. This does not mean one can stop taking vitamins, but that one's body does adapt to some degree to maximize energy nutrition with the 100 cm that it is given! :) If one eats really fatty meals one *may* also experience bloating, gas and diahhrea because the fat passes out of the system almost entirely. This should not be a problem post-op if one doesn't consume highly fatty foods often. :) The distal RNY is similar in that a higher percentage of small intestines are bypassed (the pouch is akin to the proximal RNY, though). I do believe the bypass involves different parts of the intestine, so I think more fat can be absorbed even though this is a distal procedure. The proximal/medial RNY involve a less drastic bypass. Therefore, some nutrients aren't absorbed (from the areas of intestines that are bypassed). But, since fat absorption occurs in the last section of small intestine and this is totally left intact, these procedures do result in absorption of fats. The positive note of this is that vitamin supplements are recommended/needed, but in not the same degree as with the BPD/DS or distal RNY. On the other hand, those with proximal/medial RNY must remain vigilent about fat consumption in order not to regain weight lost in the initial weight loss window. Hope this helps! A great site to get more information about the BPD/DS surgery option is: www.duodenalswitch.com All the best,
   — Teresa N.