Seven-day fast triggers broad biological changes beyond weight loss, study finds

Researchers from the Precision Healthcare Research Institute at Queen Mary University of London and the Norwegian School of Sport Sciences have identified wide-ranging biological effects of prolonged fasting that go beyond weight loss and fat burning.

The study, published in the journal Nature Metabolism and reported by ScienceDaily, found that many of these changes only appear after three days of complete calorie restriction.

Results showed that extended fasting leads to molecular shifts affecting multiple organs and systems in the body, not just changes in fat metabolism.

Using advanced techniques to analyze thousands of proteins in the blood, the researchers were able to map the body's response to fasting at the molecular level in detail.

Claudia Langenberg, director of the Precision Healthcare Research Institute, said the study provided the first clear insight into what happens in the body during fasting. She noted that safe fasting can be an effective way to lose weight, with potential health benefits that go beyond this, but these benefits appear after a longer period without food.

Mike Bitzner, head of health data at PHURI, added that understanding the molecular mechanisms behind fasting's effects could pave the way for developing treatments that mimic these benefits without requiring prolonged fasting, which could help patients unable to fast for extended periods.

The study also highlights the importance of timing in the emergence of biological changes, indicating that shorter intermittent fasting may not produce the same effects. This helps researchers distinguish between weight loss and broader biological responses.