Document details for 'Glucose uptake by the brain on chronic high-protein weight-loss diets with either moderate or low amounts of carbohydrate'

Authors Lobley, G.E., Johnstone, J.A., Fyfe, C., Horgan, G.W., Holtrop, G., Bremner, D.M., Broom, J.I., Schweiger, L. and Welch, A.
Publication details British Journal of Nutrition 11, 586-597.
Keywords ketogenic diets: glucose kinetics: ketone body metabolism: brain: positron emission tomography (PET)
Abstract Previous work showed that hunger and food intake were reduced on high-protein diets and with a greater response when the carbohydrate status induced a ketogenic (K) compared with a non-ketogenic (NK) state. The current aim was to investigate if the difference between K and NK diets was associated with changes in glucose and ketone body metabolism, particularly within key areas of the brain involved in appetite control. Twelve men, mean BMI 35.8 kg/m2, underwent a randomised cross-over trial, with two 4-week periods that involved iso-energetic fixed intake diets (~8.2 MJ/d) with 30% of the calories provided as protein and either (i) very low carbohydrate (22 g/d; K) or (ii) moderate carbohydrate (182 g/d; NK) intake. An 18fluoro-deoxyglucose (FDG) positron emission tomography (PET) scan of the brain was conducted towards the end of each period, following an overnight fast (n=4) or 4 h after a test meal (n=8). Within 48 h, whole body ketone and glucose metabolism were quantified with [13C]acetoacetate], [13C]3-hydroxybutyrate and [6,6 2H2]glucose. Whole body ketone body metabolism was approximately 4-fold greater with the K compared with NK diet (P<0.001). The 9-fold difference in carbohydrate intake between K and NK led to a 5% lower supply of glucose to the brain. Despite this, uptake of glucose by the 54 brain regions analysed remained similar between diets. The previously observed differences in intake and motivation to eat for K and NK diets does not relate to use of alternative fuels by the brain.
Last updated 2014-02-12

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