According to a new nutrition study conducted by the German Institute of human nutrition for patients with type 2 diabetes, they found that a high protein diet could reduce the fat content of the liver and could reduce the liver fat by up to 48% within 6 weeks. It doesn't matter whether the diet is based on vegetable protein or animal protein. The results were published in the international academic journal Gastroenterology.

Many studies around the world have investigated the effects of high protein diet on human metabolism. In many studies, scientists have observed that high protein diets have beneficial effects on body weight, liver fat content, blood lipid levels, long-term blood glucose levels, and muscle content. But some studies have also found that high protein intake can reduce insulin activity and affect renal function. Since different studies have observed both the positive effects of the high protein diet and the negative effects, the researchers at the German Institute of human nutrition have raised the question whether the source of protein is a determinant of different effects. So in this study, they studied the effects of two high protein diets on the metabolism of 37 participants, aged between 49 and 78, with type 2 diabetes, and most of them still fatty liver. The only difference between these two high protein diets is protein sources (plant sources and animal sources).

To ensure the stability of the participants' weight during the study, the researchers adjusted the total calories for each diet and randomly assigned participants to choose one of the high protein diets. The results showed that all the participants benefited from the high protein diet, unrelated to the protein source, and did not observe the adverse effects of the high protein diet on renal function and glucose metabolism. The liver fat content dropped most significantly, half of the participants dropped by more than 50%, while the researchers also observed a favorable change in lipid metabolism in the liver, improved insulin sensitivity, and a significant decrease in the level of FGF21 in the blood. Previous studies have found that the FGF21 of the liver can affect multiple organs, including adipose tissue, especially for overweight and obese people, and the levels of FGF21 in their blood are usually higher.

Researchers say a larger, longer term study is needed to further understand the metabolic mechanisms and the long-term effects of a high protein diet on the metabolism, and to see if young patients can benefit from this diet.

In general, researchers believe that, taking into account the results of the study and various environmental related factors, they tend to recommend people to use plant food as the main source of protein.