FGF21 and metabolic dysfunction-associated steatotic liver disease: Using a multi-omics approach, Mardinoglu and colleagues showed that the improvement of liver fat metabolism in obese adults with NAFLD after a short-term intervention with an isocaloric KD (an average of 3115 kcal/day) was characterized by a rapid decline in numerous inflammatory markers (e.g., IL-6, TNF-α) [179] and even a rapid decrease in plasma concentrations of the peptide hormone fibroblast growth factor 21.