Effects of Exercise on Fructose Metabolism

A high fructose diet increases fasting and post-prandial triglyceride (TG) concentrations in sedentary healthy human subjects.These effects may be secondary to fructose-induced hepatic de novo lipogenesis. Recent evidence indicate that exercise can prevent fructose induced dyslipidemia.This study will evaluate 1. how exercise effects the metabolic fate of oral fructose 1a) when exercise is performed before fructose ingestion 1b) when exercise is performed after fructose ingestion Metabolic effects of exercise will be assessed in healthy male subjects by measuring fructose oxidation (13CO2 production), fructose conversion into glucose (13C glucose concentrations in blood) and hepatic fructose conversion into lipid (13C palmitate-very low density lipoprotein (VLDL) concentrations in blood) after ingestion of 13C-labelled fructose meals 2. how fructose and protein modulate muscle glycogen and intramyocellular lipid repletion after exercise Healthy male subjects will be fed various fructose, glucose, lipid and whey protein meals after a glycogen/intramyocellular lipid depleting exercise. The effects of meals' composition will be assessed after 24 hours by measuring intramyocellular lipids and glycogen using proton-magnetic resonance spectroscopy (MRS).