Comparison of aspartame- and sugar-sweetened soft drinks on postprandial metabolism.

This study compared the effects of artificially sweetened (AS, via aspartame in Diet Coke) and sugar-sweetened (nutritive sweetener, NS, via Coca-Cola) beverages consumed with a mixed meal on postprandial metabolism in eight healthy young men. Results showed that NS beverages suppressed fat oxidation and increased carbohydrate oxidation compared to AS and water (control), while AS beverages did not negatively affect fat oxidation and elicited similar increases in postprandial energy expenditure despite having no calories. Plasma insulin concentrations were elevated after NS ingestion but remained lower following AS consumption, with no significant differences in blood glucose or cephalic phase insulin response among trials. The findings suggest that, acutely, aspartame-containing beverages do not adversely impact postprandial fat metabolism or insulin response compared to sugar-sweetened beverages, though the small sample size warrants cautious interpretation.