Ten subjects received alcohol by intravenous infusion on two occasions, after five-day periods on high- or low-carbohydrate diets. Blood [lactate]/[pyruvate] ratios were significantly higher during fasting alcohol metabolism after the low-carbohydrate, high-fat diet. The carbohydrate/fat balance in the diet may affect cytoplasmic-mitochondrial NADH transfer. Dietary composition may modify the metabolic changes caused by alcohol.