Impact of long-term fasting on liver and abdominal adipose tissues monitored by quantitative chemical-shift encoded...

This study used quantitative Magnetic Resonance Imaging (MRI) to explore lipid metabolism changes during a 12-day fasting intervention in the liver and abdominal adipose tissue (AT).

MRI was performed on 32 participants in the GENESIS clinical trial. This prospective, monocentric, single-arm interventional study evaluated body composition changes at four time points: before, at the end of 12 fasting days, and at 1 and 4 months after refeeding. The MRI protocol included a whole-body multi-step Dixon 3D gradient-echo sequence and a 3D chemical-shift encoded (CSE) pulse sequence to quantify different MRI metrics, such as proton density fat content (PDFF), fatty acid composition [proportion of saturated, monounsaturated, and polyunsaturated fatty acids (FA)], and T₂*. Automated segmentations extracted quantitative metrics from organs, including the liver and visceral and subcutaneous fat, and measured their volumes.

Fasting strongly reduced the liver volume (p < 0001) beyond the classical reduction in weight and blood triglyceride levels. We observed marked temporal variations in subcutaneous and visceral AT volumes, with a noteworthy continuous downward visceral fat reduction up to 4 months after fasting. Different trends were observed in liver fat content: it increased temporarily in healthy subjects, but decreased in those with liver steatosis. The increase reversed after 1 month, whereas the decrease in persistence varied during follow-up. The proportion of monounsaturated FA in AT decreased, whereas no change was observed for saturated and polyunsaturated FA during fasting.

CSE-MRI enables fast, injection-free, and quantitative monitoring of abdominal organs during fasting. Our results suggest that long-term fasting can help prevent metabolic dysfunction-associated fatty liver disease by reducing liver fat and promoting a lasting reduction in high-risk visceral fat.