|Figure 1: Effect of high protein diet on genes regulating lipogenesis [lipo = fat; genesis = production] in the liver (Stepien. 2011)|
In liver, HP feeding 1) decreased mRNA encoding glycolysis enzymes (GK, L-PK) and lipogenesis enzymes(ACC, FAS), 2) increased mRNA encoding gluconeogenesis enzymes (PEPCK), 3) first lowered, then restored mRNA encoding glycogen synthesis enzyme (GS), 4) did not change mRNA encoding b-oxidation enzymes (CPT1, ACOX1, bHAD).So, interestingly, with the exception of the 1st day of the experiment (where the increase in protein intake resulted in a short-term increase in fat oxidation), fat oxidation was stable (cf. 4) The "fat burning" effect, which is often ascribed to high protein diets, thus is not existent - or let's say its not a direct one, but a result of the synergy of other genetic and metabolic adaptations and the calorie restriction all weight loss regimens have in common.
|Figure 2: Postprandial macronutrient balance as assessed during a 4 h period after the intake of a calibrated meal consisting of 4 g of an adequate diet. (Stepien. 2011)|