The document discusses a study on the contribution of malabsorption versus food intake restriction to weight loss after Roux-en-Y gastric bypass (RYGB) surgery. The study found that: 1) 5 months after RYGB, malabsorption accounted for 124 kcal/day reduction in energy absorption while restriction accounted for 2062 kcal/day, with restriction being 16 times more important. 2) 14 months after RYGB, malabsorption accounted for 172 kcal/day reduction while restriction accounted for 1418 kcal/day, with restriction being 8 times as important. 3) On average, malabsorption contributed 6-11% of the total reduction in caloric

1. The contribution of malabsorption
to the reduction in net energy
absorption after long-limb Rouxen-Y gastric bypass

2. What is Roux-en-Y Gastric Bypass
Surgery?
• Roux-en-Y Gastric
Bypass (RYGB)
combines both
• Restrictive and
• Malabsorptive
• Components

3. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• Roux-en-Y gastric bypass (RYGB) restricts food
intake, and
• when the Roux limb is elongated to 150 cm, the
procedure is believed to induce malabsorption
• Objective measure reduction calories after
RYGB
• Restriction of food intake vs Malabsorption
•
The contribution of malabsorption to the reduction in net energy absorption after longlimb Roux-en-Y gastric bypass, Elizabeth A Odstrcil, et al. Am J Clin Nutr October
2010 vol. 92 no. 4 704-713

4. The contribution of malabsorption
to the reduction in net energy
absorption after long-limb
Roux-en-Y gastric bypass
The contribution of malabsorption to the reduction in net energy absorption
after long-limb Roux-en-Y gastric bypass
Elizabeth A Odstrcil, Juan G Martinez, Carol A Santa Ana, Beiqi Xue, Reva
E Schneider, Karen J Steffer, Jack L Porter, John Asplin, Joseph A Kuhn,
and John S Fordtran
Am J Clin Nutr October 2010 vol. 92 no. 4 704-713

5. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• No statistically significant effects of
RYGB on
• Protein or
• Carbohydrate absorption coefficients
•
The contribution of malabsorption to the reduction in net energy
absorption after long-limb Roux-en-Y gastric bypass, Elizabeth A
Odstrcil, et al. Am J Clin Nutr October 2010 vol. 92 no. 4 704-713

6. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• 5 months after bypass,
• Malabsorption reduced absorption of
combustible energy by 124 ± 57 kcal/d,
whereas
• Restriction of food intake reduced energy
absorption by 2062 ± 271 kcal/d
• In RNY Restriction 16 times more
important than Malabsorption
•
The contribution of malabsorption to the reduction in net energy absorption
after long-limb Roux-en-Y gastric bypass, Elizabeth A Odstrcil, et al. Am J
Clin Nutr October 2010 vol. 92 no. 4 704-713

7. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• 14 months after bypass,
• Malabsorption reduced absorption of
combustible energy by 172 ± 60 kcal/d,
whereas
• Restriction of food intake reduced energy
absorption by 1418 ± 171 kcal/d
• Restriction 8 times as important as
Restriction
• (Why: Restriction Beginning to Fail)
•
The contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric bypass, Elizabeth A Odstrcil,
et al. Am J Clin Nutr October 2010 vol. 92 no. 4 704-713

9. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• On average, malabsorption accounted for
6% and 11% of the total reduction in
ccaloric intake at 5 and 14 mo,
respectively, after 150 RNY gastric bypass
• RNY: Primarily a Restrictive Procedure
• NOTE: Early signs of failure
•
The contribution of malabsorption to the reduction in net energy absorption
after long-limb Roux-en-Y gastric bypass, Elizabeth A Odstrcil, et al. Am J
Clin Nutr October 2010 vol. 92 no. 4 704-713

10. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• Dietary intake and net intestinal absorption of
fat, protein, and carbohydrate were measured
• Calculated the total reduction in fat, protein,
carbohydrate, and calories after RYGB
• Extent to which these reductions were due to
restriction or malabsorption
•
The contribution of malabsorption to the reduction in net energy absorption after longlimb Roux-en-Y gastric bypass, Elizabeth A Odstrcil, et al. Am J Clin Nutr October
2010 vol. 92 no. 4 704-713

11. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
•
•
•
•
•
Fat absorption and malabsorption
Average fat intake was
156 g/d before bypass,
50 g/d 5 mo after bypass, and
82 g/d 14 mo after bypass.
•
The contribution of malabsorption to the reduction in net energy absorption
after long-limb Roux-en-Y gastric bypass, Elizabeth A Odstrcil, et al. Am J
Clin Nutr October 2010 vol. 92 no. 4 704-713

13. Correlation between the length of jejunum in the
biliopancreatic (BP) limb and the reduction in coefficient of
fat absorption at 5 (A) and 14 (B) mo after long-limb Rouxen-Y gastric bypass (RYGB).

14. The contribution of malabsorption to the reduction in net
energy absorption after long-limb Roux-en-Y gastric bypass
• RNY does not cause bile acid
malabsorption
• Fecal bile acid excretion averaged
• Before: 0.78 ± 0.08 g/d,
• 5 mo: 0.50 ± 0.13 g/d, and
• 14 mo: 0.68 ± 0.12 g/d
• Decreased Bile Acids Rx Diabetes

15. Post Gastrectomy Steatorrhea
• Several authors have noted that
• Fat malabsorption
• More common and to a Greater
degree with
• Billroth II >> Billroth I
•
•
•
EVERSON TC. Experimental comparison of protein and fat assimilation after Billroth II, Billroth I, and segmental
types of subtotal gastrectomy. Surgery. 1954 Sep;36(3):525-37
MACLEAN LD, PERRY JF, KELLY WD, MOSSER DG, MANNICK A, WANGENSTEEN OH. Nutrition following
subtotal gastrectomy of four types (Billroth I and II, segmental, and tubular resections). Surgery. 1954
May;35(5):705-18
WOLLAEGER EE, WAUGH JM, POWER MH. Fat-assimilating capacity of the gastrointestinal tract after partial
gastrectomy with gastroduodenostomy (Billroth I anastomosis). Gastroenterology. 1963 Jan;44:25-32

16. Steatorrhoea following
Gastric Operations:
• Rare after gastro-jejunostomy or vagotomy
alone.
• Rare after Billroth I
• Common after Polya gastrectomy.
• The addition of vagotomy to gastrectomy or
gastrojejunostomy increased the fat
• content of the stools.
• (Butler, 1961)

17. Factors implicated as the cause of increased
Body fat loss following gastrectomy & Billroth II
• Decreased caloric intake
• Gastrointestinal motility
changes
• Reservoir function are
responsible for the
steatorrhea.

18. Factors implicated as the cause of increased
fat loss following partial gastrectomy & Billroth
II
• In a clinical study, Saxon and Ziese
stated that
• Loss of the reservoir function of the
stomach was of primary cause.
• Loss of body weight correlated
significantly with the
• amount of stomach removed at
operation and with no other factors.

19. Factors implicated as the cause of increased
fat loss following partial gastrectomy & Billroth
II
• Waddell and Wang Abnormal motility
rather than lack of reservoir function
was the basic physiologic disturbance
involved.
• Glazebrook and Welbourn 6 indicted
intestinal hypermotility as the cause

20. Fat absorption and the
Billroth II Afferent loop
• An experiment was designed first, to
determine whether progressive increase in
the length of the afferent loop was
predictably associated with increasing fat
malabsorption
• Animals underwent a 50% distal
gastrectomy with an antecolic
• Polya-type Billroth II anastomosis

21. Polya Type Gastro-Jejunostomy

23. Fat absorption and the
Billroth II Afferent loop
• Animals underwent
a 50% distal
gastrectomy with
an antecolic
• Polya-type Billroth
II anastomosis
• Afferent loops of
• 30, 60, and 90 cm.

24. Fat absorption and the
Billroth II Afferent loop
• Average fecal excretion on a 127 Gm. diet
was 2.4% of the ingested fat.
• Similar to results both in dogs and in
humans
• Animals with 30 cm. afferent loops
• Able to digest and absorb the fat diet
without any apparent difficulty

25. Fat absorption and the
Billroth II Afferent loop
• Average fecal excretion diet was
2.4% of the ingested fat.
• Longer Loops steatorrhea increased
• 30 cm. loop fecal fat 2.4% (No Change)
• 60 cm. loop fecal fat excretion 10.2%
• 90 cm. loop 28.2%

26. Fat absorption and the
Billroth II Afferent loop
• Average fecal excretion diet was
2.4% of the ingested fat.
• Longer Loops steatorrhea increased
• 30 cm. loop fecal fat 2.4% (No Change)
• 60 cm. loop fecal fat excretion 10.2%
• 90 cm. loop 28.2%

27. Fat MAL-absorption and the
Billroth II Afferent loop
• Afferent loop can be a most important factor
in the cause of post gastrectomy
steatorrhea, depending upon the LENGTH
of its construction.
• Animals with short afferent loops did not
demonstrate any significant steatorrhea.
• As the length of the afferent loop increased,
a concomitant and dramatic rise in fecal fat
excretion was noted.

28. Fat MAL-absorption and the
Billroth II Afferent loop
• The malabsorption is probably not
due to bypass of the upper jejunum
• Kremen’s demonstration in dogs
that
• Over half the jejunum can be
bypassed without producing
steatorrhea.

29. • An Experimental Evaluation of the
Nutritional Importance of Proximal
and Distal Small Intestine
• Arnold J. Kremen, et al.
• Ann Surg. 1954 September; 140(3): 439–447

30. Kremen, et al.
• Experimental studies in dogs reveal
that animals also can, with
reasonable assurance,
• be deprived of from 50 to 70 per cent
of their small intestine and maintain a
near normal nutritional status.

31. Experimental Evaluation of the Nutritional
Importance of Proximal and Distal Small Intestine
• Study showed that after sacrifice of
major lengths of the proximal small
intestine,
• the animal's weight is satisfactorily
maintained near preoperative levels,
and
• no great interference with fat
absorption is observed.

32. Experimental Evaluation of the Nutritional
Importance of Proximal and Distal Small Intestine
• 50- 70% of the mesenteric small bowel
bypassed
• The bypassed bowel had its blood supply
preserved and
• proximal and distal ends were exteriorized as a
cutaneous stoma.
• Intestinal continuity was re-established by endto-end anastomosis

34. 50% of Jejunum Bypassed

35. Massive bypass = No Effect
• The small intestine in adults is a
long and narrow tube about
7 meters (23 feet) long
• 50% Bypass = 11.5 ft (3.5 meters)
• Minimal Weight Loss!

36. 70% Bowel Bypassed

37. Massive bypass = Little Effects!
• The small intestine in adults is
a long and narrow tube about
7 meters (23 feet) long
• 70% Bypass = 16 ft (5 meters)
• 5% weight loss

38. 70% Bypass = Little Effect
• Group IV animals, which were
similar to Group I except that 70%
instead of 50% of proximal small
bowel removed from intestinal
continuity,
• Lost about five per cent of their
preoperative weight and then
stabilized at this level.

39. Transit Time & Fat Absorption
• 50-70% Bypass
• Made Little Difference in
Transit Time
• Fat Absorption NOT affected

40. Experimental Evaluation of the Nutritional
Importance of Proximal and Distal Small Intestine
• CONCLUSIONS
• The proximal 50 to 70 per cent of the small
intestine can be removed with no apparent ill
effects.
• Weight is maintained, and protein and fat
absorption are not significantly altered.
•
Arnold J. Kremen, John H. Linner, and Charles H. Nelson

41. Absorption studies after gastrojejunostomy
with and without vagotomy
• It is concluded that serious malabsorption does not
follow either gastrojejunostomy or vagotomy
• but may occur quite often when these procedures are
combined.
• It seems that the addition of vagotomy to the G-J is
responsible for steatorrhea.
• Presumably vagotomy interferes with the gastric,
intestine, or biliary response to food.