Experiments were performed on rats involving small intestinal resection or bypass and subsequent measurement of villus height and of the rate of migration of labelled cells along the villus. The height of jejunal villi was increased 10% following distal small bowel resection as compared with 39% following distal bypass. Thus, there was no evidence to support the hypothesis that compensatory hypertrophy is a consequence of the loss of tissue mass. Instead, the observation that growth may be induced by bypass alone suggests that the concept of compensatory growth should be broadened to include adaptive changes resulting from functional derangements. It also suggests a possible explanation for the failure of some patients to sustain initial rates of weight loss after bypass procedures for morbid obesity.
Tilson MD. Compensatory Hypertrophy of the GutTesting of the Tissue Mass, Intraluminal Nutrition and Functional Demand Hypothesis. Arch Surg. 1972;104(1):69-72. doi:10.1001/archsurg.1972.04180010063016