The human body can survive without food for some time before starvation is likely to cause significant damage to the body.
In fact, when done correctly and under medical supervision, fasting is believed to offer a range of benefits. benefits for people’s health — but these benefits may not occur in shorter or more intermittent fasts, according to recent research.
A study by researchers in Europe and the United Kingdom found that it took more than three days for all major organs to change protein production in a way that could predict better health in participants undertaking a seven-day fast. days water-based only.
These changes were consistent among the 12 healthy participants (five women and seven men), whose blood was collected before, during and after the week of fasting.
“For the first time, we are able to see what happens at the molecular level throughout the body when we fast,” explain Claudia Langenberg, epidemiologist from Queen Mary University of London.
“Our results provide evidence of health benefits of fasting beyond weight loss, but these were only visible after three days of total calorie restriction – later than we previously thought.”
That’s a lot of time to deprive the human body of calories, which introduces serious risks that may not be worth the expected results.
When practiced safely and under the supervision of a healthcare professional, fasting can have health benefits, but its downsides should also be carefully considered for each individual. Doctors generally advises that children, adolescents, pregnant people or people affected diabetes or eating disorders do not participate in intermittent fasting.
There is a risk of dehydration when fasting, because about 20 percent Much of our usual fluid intake comes from food. So individuals should also ensure that they consume plenty of water.
Fasting for several days can be dangerous and its potential benefits are not yet clearly demonstrated. That said, if more research can be done, scientists may be able to mimic the benefits of fasting without anyone having to deprive themselves of calories.
In recent years, many studies to have suggested that intermittent fasting – as opposed to prolonged fasting in the study – may improve certain aspects of human health. These include weight loss, lowering blood pressure, improving bone density and controlling appetite.
Some experiments have even shown that feeling hungry for short periods of time can slow down the natural aging process And possibly extend a person’s lifespan.
However, scientists have a very limited understanding of what actually happens to the human body when it adapts to starvation. Clinical trials on the subject are limited, meaning that healthcare professionals do not have evidence-based advice to give to patients.
In research published earlier this year, scientists found that of the approximately 3,000 proteins measured in participants’ blood, about a third showed “profound systemic changes” after consuming only water for seven days.
The protein changes thought to have the greatest health benefits, however, were only observed after three consecutive days of fasting. These include protein changes linked to improvements in rheumatoid arthritis and cardiovascular health.
The results support pass testswhich also suggest that fasting requires several days before it becomes more useful than simply reducing calorie intake.
Most protein returns to baseline as soon as a person starts eating again, suggesting that the biological changes associated with fasting must be sustained for a period of time to gain long-term health benefits.
“Lack of food has been the default situation throughout human evolution, and our bodies are the result of a selection process aimed at high metabolic flexibility to survive long periods without food.” explain the authors of the study.
“Our findings provide an opportunity to systematically identify the potential health benefits of fasting and translate this knowledge into putative interventions, including for patients who cannot adhere to prolonged fasting programs or diets mimicking fasting. young.”
Because the study sample size is extremely small, the results are unlikely to be representative of the effects of fasting on a diverse human population. The international team of scientists hope their results will provide an important reference point for future research into fasting.
The study was published in Natural metabolism.
An earlier version of this article was published in March 2024.