Peripheral insulin sensitivity as modified by diet and exercise training.

To determine which component of a high-fat sucrose diet (HFS) caused insulin resistance and whether exercise training or fiber could prevent it, six dietary treatments were tested in rats: low-fat complex carbohydrate (LFCC); high-fat complex carbohydrate (HFCC); low-fat sucrose (LFS); high-fat sucrose (HFS); HFS plus fiber (HFS + F); and HFS plus exercise training (HFS + EX). After 10 wk rats were subjected to an intravenous glucose-tolerance test. The HFS and HFS + F groups developed glucose intolerance, as indicated by significantly greater areas under their glucose curves compared with the LFCC group's areas. The LFS, HFS, HFS + F, and HFS + EX groups developed insulin resistance, as indicated by significantly greater areas under their insulin curves compared with the LFCC and HFCC groups' areas. Either the presence of sucrose or the absence of complex carbohydrates, not high fat, was responsible for the insulin resistance and it was not improved by adding fiber to the diet or by exercise training.