Effects of 3 days of ‘postoperative’ low caloric feeding with or without bed rest on insulin sensitivity in healthy subjects

Background and Aims: Insulin resistance after surgery is caused by the surgical trauma and presumably also by other factors, such as starvation and immobilization. The purpose of this study was to evaluate the effect of traditional postsurgical low caloric feeding and bed rest on insulin sensitivity and substrate utilization, in younger and older healthy subjects. Methods: Twelve healthy subjects underwent hyperinsulinaemic, normoglucaemic clamps and indirect calorimetry before and after 3 days of bed rest and low caloric feeding. Six of the subjects underwent a second study with 3 days of low caloric feeding without bed rest. Results: Insulin sensitivity decreased by 57±16 % after low caloric feeding combined with bed rest, with no difference between age groups, and by 56±9% after low caloric feeding only. Glucose oxidation decreased, while fat oxidation increased. No significant differences were seen between age groups or between the protocols. Conclusions: Low caloric feeding, a commonly used nutritional routine in clinical practice, induce marked alterations in insulin sensitivity and substrate utilization. Increasing age or bed rest did not seem to influence this development. These findings suggest that the routine low caloric feeding is capable of contributing to postoperative insulin resistance.