Short-term weight loss and hepatic triglyceride reduction: evidence of a metabolic advantage with dietary carbohydrate restriction

BACKGROUND: Individuals with nonalcoholic fatty liver disease (NAFLD) have excess intrahepatic triglycerides. This is due, in part, to increased hepatic synthesis of fat from carbohydrates via lipogenesis. Although weight loss is currently recommended to treat NAFLD, little attention has been given to dietary carbohydrate restriction. OBJECTIVE: The aim of this study was to determine the effectiveness of 2 wk of dietary carbohydrate and calorie restriction at reducing hepatic triglycerides in subjects with NAFLD. DESIGN: Eighteen NAFLD subjects (n = 5 men and 13 women) with a mean (±SD) age of 45 ± 12 y and a body mass index (in kg/m(2)) of 35 ± 7 consumed a carbohydrate-restricted (<20 g/d) or calorie-restricted (1200-1500 kcal/d) diet for 2 wk. Hepatic triglycerides were measured before and after intervention by magnetic resonance spectroscopy. RESULTS: Mean (±SD) weight loss was similar between the groups (-4.0 ± 1.5 kg in the calorie-restricted group and -4.6 ± 1.5 kg in the carbohydrate-restricted group; P = 0.363). Liver triglycerides decreased significantly with weight loss (P < 0.001) but decreased significantly more (P = 0.008) in carbohydrate-restricted subjects (-55 ± 14%) than in calorie-restricted subjects (-28 ± 23%). Dietary fat (r = 0.643, P = 0.004), carbohydrate (r = -0.606, P = 0.008), posttreatment plasma ketones (r = 0.755, P = 0.006), and respiratory quotient (r = -0.797, P < 0.001) were related to a reduction in liver triglycerides. Plasma aspartate, but not alanine, aminotransferase decreased significantly with weight loss (P