Transform your health in a week? What a 7-day fast can do

In a study published recently in Nature Metabolism, researchers have unveiled the profound and systematic changes that occur across multiple organs during a 7-day fast.

Conducted by the team from Queen Mary's Precision Healthcare University Research Institute (PHURI) in collaboration with the Norwegian School of Sports Sciences, the study offers new insights into the benefits of fasting beyond mere weight loss. It identifies significant health-altering changes that commence after three days without food.

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What a 7-Day Fast can do

7-Day Fast (Image via Unsplash/Giorgio Trovato)

Fasting, a practice deeply rooted in various cultures and religions, has been traditionally associated with the treatment of diseases such as epilepsy and rheumatoid arthritis.

Despite its long history, the specific effects of a 7-day fast on the body's internal processes have remained largely uncharted until now. The advent of new techniques that allow for the measurement of thousands of proteins circulating in our blood has opened up unprecedented avenues for the detailed study of fasting's molecular adaptations in humans.

The research team followed 12 healthy volunteers who underwent a seven-day water-only fast. The participants were meticulously monitored daily to track changes in approximately 3,000 proteins in their blood before, during, and after the fasting period.

This comprehensive approach enabled the researchers to pinpoint the proteins involved in the body's response to a 7-day fast and, by integrating genetic information from large-scale studies, predict potential health outcomes of prolonged fasting.

One of the study's key findings was the body's transition from utilizing glucose to burning stored fat for energy, typically occurring within the first two or three days of fasting.

Remarkably, the participants lost an average of 5.7 kg of both fat and lean mass, with the weight loss being sustained post-fast; lean mass loss was almost entirely reversed, but fat mass did not return.

For the first time, distinct changes in protein levels signaling a whole-body response to complete calorie restriction were observed after about three days of fasting.

7-Day Fast (Image via Unsplash/Vitalii)

These changes, significant across all major organs, were consistent among the volunteers, highlighting unique fasting-related signatures such as alterations in proteins that support brain neuron structure.

Claudia Langenberg, Director of PHURI, emphasized the novelty of their findings, stating:

"For the first time, we're able to see what's happening on a molecular level across the body when we fast. Fasting, when done safely, is an effective weight loss intervention. 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."

Maik Pietzner, Health Data Chair of PHURI and co-lead of the Computational Medicine Group at the Berlin Institute of Health at Charité, further reflected on the implications of their research:

"Our findings have provided a basis for some age-old knowledge as to why fasting is used for certain conditions. 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."

This study not only advances our understanding of the physiological processes ignited by a 7-Day Fast but also paves the way for future research that could lead to therapeutic interventions for individuals who cannot fast due to medical reasons.