To investigate the acute and longer term effects of low (LGI) v high (HGI) glycaemic index diets on hepatic fat and glycogen accumulation and related blood measures in healthy volunteers.
Eight healthy males (age = 20.1 ± 0.4y, BMI=23.0 ± 0.9 kg/m2) attended a test day before and after a 7-day macronutrient and energy matched HGI or LGI diet, followed by a minimum 4 week wash-out period, and then returning to repeat the intervention with the alternative diet. During test days, participants consumed either a HGI or LGI test meal corresponding to their diet week, and liver fat (1 H MRS), glycogen (13 C MRS) and gastric content volume (MRI) were measured. Blood samples were obtained regularly throughout the test day for plasma glucose and insulin.
Plasma glucose and insulin peak values and AUC were significantly greater following the HGI test meal compared with LGI test meal as expected. Hepatic glycogen concentrations increased more following the HGI test meal (P < 0.05) and peak levels were significantly greater after 7 days of HGI dietary intervention compared to that at the beginning of the intervention (P < 0.05). Liver Fat fractions increased significantly following the HGI dietary intervention compared with the LGI dietary intervention (two way repeat measures ANOVA, P ≤ 0.05).
Compared to an LGI diet, a one week HGI diet increased hepatic fat and glycogen stores. This may have important clinical relevance for dietary interventions in the prevention and management of non-alcoholic fatty liver disease. CLINICAL TRIALS REGISTRY NUMBER AND WEBSITE This study was registered at clinicaltrials.gov, ID: NCT02482558.