Fasting’s popularity has grown in recent years with proposed benefits including fat loss, supercharged immunity, and cognitive improvement, but a new study from the Queen Mary University in London has tracked thousands of proteins in the blood to figure out exactly what happens, and when, during a 7-day water fast.
This latest work on the effects of fasting, published in Nature Metabolism, took notice of the fact that human evolution has been underscored by periods of prolonged food restriction. But whether this be due to scarcity, religious practice, or the treatment of disease, there is still much to learn about what missing meals actually means for our overall health. To add weight to the body of information on this subject, they looked at the internal transformations that take place as a result of putting down our plates.
How Was the Study Carried Out?
Researchers from the Precision Healthcare University Research Institute (PHURI) and the Norwegian School of Sports Sciences, looked at 12 healthy volunteers as they undertook a seven-day water-only fast. Blood samples were collected before, during, and after fasting, tracking around 3,000 circulating proteins to figure out the real-life effects.
What Happens to Your Body During a 7-Day Water Fast?
Day 1: Once fasting began, the body shifted quickly from burning glucose to utilizing fast stores instead.
Day 3: While the body did begin to make adaptations from the start of the fast, the team found that the major molecular changes began to kick in after approximately three days without calorie intake, surprising the scientists.
One of the most important findings was that ECM proteins, providing support for connective tissue, skin, cartilage, and neural tissues was enriched, suggesting that prolonged fasting may trigger tissue remodeling and repair, going far beyond simple fats loss.
Day 7: The proteins, including brain related proteins began to change substantially from day 3 to 7, including Tenascin-R, a protein that supports neural plasticity, signaling improvements, and brain remodeling. Inflammation and immune signaling also shifted, providing potential benefits with rheumatoid arthritis, cardiovascular disease, and cellular stress.
By the end of the fast, subjects lost an average total weight of around 12.5 pounds. When the individuals began eating again, the fat was largely preserved, with the initial weight gain coming by way of glycogen restoration and water retention.
What the Study Revealed About Metabolism and Glycogen Stores
“For the first time, we’re able to see what’s happening on a molecular level across the body when we fast,” explained Claudia Langenberg, director of the PHURI at Queens Mary University London. “Fasting, when done safely, is an effective weight loss intervention. Popular diets that incorporate fasting—such as intermittent fasting—claim to have health benefits beyond weight loss. Our results provide evidence for the health benefits of fasting beyond weight loss, but these were only visible after three days of total caloric restriction—later than we previously thought.”
Is a 7-Day Fast Safe? What Researchers Want You to Know
Despite the potential benefits, prolonged fasting requires careful consideration, it is not suitable for everyone, and you should seek the advice of a medical professional who can look at your individual circumstances. “While fasting may be beneficial for treating some conditions, often times, fasting won’t be an option to patients suffering from ill health,” advised PHURI’s Health Data Chair, Maik Pietzner. “We hope that these findings can provide information about why fasting is beneficial in certain cases, which can then be used to develop treatments that patients are able to do.”