Gaby
Millions of people around the world are losing weight by following diets or fasting for religious reasons. However, the biological consequences of prolonged calorie restriction have remained poorly understood.
A team of scientists from Germany, the UK, Norway, and Denmark analyzed the systemic changes that occur in various organs during extended periods without food. They discovered both positive and negative health effects, as reported by IFLScience.
What the Researchers Learned
The authors of the study recruited 12 healthy volunteers to participate in a seven-day fast, during which they were allowed to drink water but prohibited from eating. Throughout the experiment, the researchers closely monitored the health status of the participants. They measured changes in approximately 3,000 different blood proteins daily. These proteins are the fundamental building blocks for all cells and tissues in the body.
The authors noted that within the first few days of fasting, the volunteers’ bodies shifted their energy source: they began burning stored fat instead of glucose. As a result, participants lost an average of 5.7 kilograms over the week. Interestingly, this weight was maintained even after the volunteers resumed eating.
However, to their surprise, the researchers did not observe significant changes in blood protein levels during the initial days of fasting. The situation changed dramatically after the third day, when the levels of hundreds of proteins that have a substantial impact on health began to fluctuate significantly.
The scientists compared their findings with results from genetic studies that linked various proteins in blood plasma to different diseases. This allowed them to assess the health implications of the changes in levels of 212 proteins observed during fasting.
For instance, they found that abstaining from food for more than three days led to a decrease in the protein SWAP70. Lower levels of this protein are associated with a reduced risk of developing rheumatoid arthritis (RA). The researchers suggested that this discovery could contribute to at least a partial reduction in pain for RA patients.
They also observed a decrease in the protein HYOU1, which is linked to ischemic heart disease. Thus, the team believes that intermittent fasting may have beneficial effects on heart health.
At the same time, the researchers identified several negative health consequences associated with fasting. For example, they observed increased blood clotting, which potentially raises the risk of thrombosis.
“For the first time, we saw what happens at the molecular level in the body when we fast,” said study author Claudia Langenberg. “Our results demonstrated the health benefits of fasting (beyond weight loss), but these benefits were only noticeable after three days of complete calorie restriction—later than we expected,” she added.
Summarizing the findings, Mike Pitzner, another author of the study, noted that “while fasting can be beneficial for treating certain conditions, it often isn’t suitable for patients with health issues.”
The results of the study were published in the journal Nature Metabolism.
