Nutrition & DietSeven Days of Fasting Triggers Dramatic Body-Wide Changes After Day Three
A new study published in Nature Metabolism tracked roughly 3,000 proteins in the blood of 12 healthy volunteers during a seven-day water-only fast. Researchers from Queen Mary University of London found that while the body shifts from burning glucose to fat within the first two to three days, the most significant molecular changes — affecting the brain, immune system, and metabolism — only appeared after the three-day mark. More than one third of all proteins measured changed significantly during the fast. Participants lost an average of 12.5 pounds, with fat loss persisting after refeeding while lean tissue largely recovered. Scientists say the findings suggest the body enters a distinct biological mode during prolonged fasting, and the work could help develop therapies that mimic fasting's effects without requiring people to stop eating.
