Non-alcoholic fatty liver diseases (NAFLD) are particularly widespread in industrialized countries. Lifestyle changes with a balanced diet and increased exercise are still the treatment of choice for fatty liver disease. DZD researchers were able to show that a calorie-reduced diet with a high protein content reduced liver fat more effectively than a calorie-reduced low-protein diet. The results were published in the journal Liver International.

The researchers investigated how the protein content of the diet affects the amount of liver fat in severely overweight people with a non-alcoholic fatty liver. For this purpose, 19 participants with morbid obesity undergoing bariatric surgery were randomized into two hypocaloric (1500‐1600 kcal/day) diet groups, a low protein (LP) and a high protein (HP), for three weeks prior to surgery. Intrahepatic lipid levels (IHL) and serum fibroblast growth factor 21 (FGF21) were measured before and after the dietary intervention. Autophagy flux, histology, mitochondrial activity and gene expression analyses were performed in liver samples collected during surgery.

The group that received a high-protein diet lost about five kilograms and IHL levels decreased by 42.6 %. In the LP group, IHL values did not change significantly despite similar weight loss. Hepatic autophagy flux and serum FGF21 increased by 66.7% and 42.2%, respectively, after 3 weeks in the LP group only. Expression levels of fat uptake and lipid biosynthesis genes were lower in the HP group compared with those in the LP group. RNA‐seq analysis revealed lower activity of inflammatory pathways upon HP diet. Hepatic mitochondrial activity and expression of β‐oxidation genes did not increase in the HP group.

The HP diet reduces liver fat more effectively than the LP diet despite less autophagy. The data suggest that the liver fat reduction in HP diet results primarily from the suppression of fat absorption and lipid biosynthesis.

Original publication:
Xu, C., Markova, M., Seebeck, N., Loft, A., Hornemann, S., Gantert, T., Kabisch, S., Herz, K., Loske, J., Ost, M., Coleman, V., Klauschen, F., Rosenthal, A., Lange, V., Machann, J., Klaus, S., Grune, T., Herzig, S., Pivovarova-Ramich, O., Pfeiffer, A. F. H.: High-protein diet more effectively reduces hepaticfat than low-protein diet despite lower autophagy and FGF21 levels. Liver Inter. in press (E-pub ahead of print) (2020). [Open Access] [https://doi.org/10.1111/liv.14596]