The effect of
dietary sucrose and fat in the form of coconut fat (rich in
saturated fatty acids) or safflowerseed oil (rich in
polyunsaturated fatty acids) was examined on the development of
obesity and impaired
glucose homeostasis in ob/ob mice. Isoenergetic high
sucrose or high fat diets were fed to ob/ob mice from 3-11 weeks of age. Energy intake of mice fed diets rich in fat were similar, and exceeded that attained with the
sucrose diet.
Body weight gain was greatest in the
sucrose-fed mice and least in those fed safflowerseed oil. With the exception of
insulin sensitivity which was enhanced with safflowerseed oil, plasma concentrations of
glucose and
gastric inhibitory polypeptide (GIP),
glucose tolerance, intestinal GIP content and the GIP response to oral fat were similar. However, mice fed the high
sucrose diet exhibited markedly elevated plasma
insulin concentrations and an enhanced pancreatic
insulin content. Since the hyperinsulinaemic action of
sucrose cannot be attributed to elevated GIP or
glucose concentrations, the involvement of other
insulin-releasing
hormones released from the intestine by
sucrose is suggested. The results indicate that the relative amounts of
carbohydrate and fat in the diet have an important modulating effect on the development of the ob/ob syndrome. The type of
fatty acids in the diet does not appear to be a particularly important determinant for expression of the ob gene.