A seven-day water-only fast triggers major molecular shifts across the body, with the most significant effects emerging only after three days without food. Researchers tracked protein changes in healthy volunteers to map these responses in detail. The findings highlight both potential health benefits and risks of prolonged fasting.
Researchers at Queen Mary University of London and the Norwegian School of Sports Sciences monitored 12 healthy volunteers during a seven-day fast. They collected daily blood samples and analyzed around 3,000 proteins to observe internal changes. The body switched from using glucose to burning fat within the first two to three days, resulting in an average weight loss of 5.7 kilograms. Most lean tissue loss recovered after eating resumed, while fat loss largely remained.
