Effect on the interaction of dietary carbohydrate and fat on the responses of rats to starvation-refeeding.

The interacting effects of sucrose or starch with corn or coconut oil on the lipogenic responses of rats to starvation-refeeding was studied. Rats were either ad libitum-fed or starved for 48 h and refed for 48 h. Four different diets were used: 65% starch-5% corn oil, 65% starch-5% coconut oil, 65% sucrose-5% corn oil, 65% sucrose-5% coconut oil. Lipogenesis was assessed in two ways: glucose-6-phosphate dehydrogenase (G6PD) activity, malic enzyme (ME) activity and percent liver lipid (expt 1) and tritium (3HOH) incorporation into fatty acids (expt 2). Starved-refed rats had more liver lipid, greater enzyme activity and greater 3H incorporation into fatty acids than ad libitum-fed rats. Sucrose-fed rats had more lipogenic activity than starch-fed rats. Rats fed coconut oil were more lipogenic than rats fed corn oil. There were highly significant correlation coefficients between the enzyme activities (G6PD and ME) and the percent liver lipid and between the enzyme activities and 3H incorporation into fatty acid. Analysis of variance of these data revealed significant dietary effects on these lipogenic responses to starvation-refeeding. We conclude that both dietary carbohydrate and lipid play a significant role in the determination of the magnitude of the lipogenic response to starvation-refeeding.