β Hydroxybutyrate Upregulates FGF21 Expression Through Inhibition Of Histone Deacetylases In Hepatocytes

This study investigated how ketones, specifically beta-hydroxybutyrate (β-OHB), affect the production of an important metabolic hormone called FGF21 in liver cells. Beta-hydroxybutyrate is one of the main ketone bodies your body produces when you're fasting, following a very low-carb diet, or in a state called ketosis. FGF21 is a hormone that acts like a metabolic "switch," helping your body better use glucose, lower triglycerides, promote weight loss, and reduce inflammation.

The researchers tested their theory both in lab-grown human liver cells and in live mice. They found that when beta-hydroxybutyrate levels increased, it led to significantly higher production and release of FGF21. The mechanism works by beta-hydroxybutyrate inhibiting certain enzymes called histone deacetylases (HDACs), which normally suppress FGF21 production. By blocking these enzymes, beta-hydroxybutyrate essentially "turns on" the genes responsible for making more FGF21.

This discovery is particularly exciting because FGF21 has shown promise as a potential treatment for metabolic diseases like type 2 diabetes, obesity, and fatty liver disease. The hormone appears to help the body become more metabolically flexible and efficient at burning different fuel sources. Understanding how ketones naturally boost FGF21 production provides insight into why ketogenic diets and intermittent fasting may have metabolic benefits.

For clinical practice, this research helps explain some of the metabolic advantages seen with nutritional approaches that increase ketone production, such as ketogenic diets, intermittent fasting, or MCT oil supplementation, and may guide future therapeutic strategies for metabolic health optimization.