Periods of fasting to protect against obesity and diabetes? This is the track followed by scientists at the Salk Institute for Biological Studies in California. In the Cell Metabolism review published on August 30, they show that spreading the calories consumed daily over a period of 10 hours a day (known as intermittent fasting) would prevent metabolic disorders such as obesity or diabetes.
“For many of us, the day starts with a cup of coffee first thing in the morning and ends with a bedtime snack 2 or 3 hours later. develops Satchidananda Panda, professor at the Salk Institute and lead author of the study. But limiting your food intake to 10 hours a day and fasting the rest can lead to better health, regardless of your biological clock. » Because it is indeed the biological clock that is in question.
Synchronization of cell clocks
In fact, to reach this conclusion, two studies were necessary. For the first, Satchidananda Panda and his team worked with two groups of mice: the first with unlimited access to high-fat food and the second with access limited to 10 hours a day to this same food. They then showed that mice with 24-hour access to a fatty diet developed metabolic diseases, including high cholesterol or diabetes. But the mice of the 2nd group, they had become “thin”, healthy and healthy.
They concluded that this beneficial effect of a reduced feeding time slot (8 to 10 a.m. VS 24 a.m.) was due to a better synchronization of their cell clocks. Because each cell works according to a cycle that lasts 24 hours, called circadian rhythm. This biological rhythm breaks down into several phases during the day. Thus, in humans, the digestion genes are more active fairly early in the day, while the cell repair genes are more active at night, during the fasting period.
To confirm their hypothesis, another study was needed. They then wanted to test this same protocol (24-hour access to fat-enriched food VS food available 10 hours a day) on mice whose internal clock was deactivated (genetically modified mice).
They expected mice in two groups to develop metabolic diseases, being the lack of a biological clock to tell cells what to do when.
However, it turns out that even in mice without a clock, eating only 10 hours a day was enough to prevent them from metabolic diseases: they too were in good health.
Balance between digestion and cell repair
How to explain it? “In fact, our first study led us to believe that the biological clock was programmed to ‘turn off’ and ‘turn on’ metabolic genes at given times, explains Amandine Chaix, scientist at the Salk Institute. And while that may be true, our new study suggests that controlling eating and fasting cycles (by enforcing food intake times) can compensate for the lack of an internal clock. »
In other words, they think that the internal clock is used in particular to dictate the times to eat and those to abstain from. Thus, disturbances of this biological clock – especially among night workers, flight personnel, etc. – promote the development of metabolic diseases, the body no longer knowing when to consume energy and when to spend it.
The good news, say the scientists, is that a simple lifestyle change – eating for 10 hours – could stave off these diseases and stay healthy. The disturbances of the internal clock are in this way rebalanced by an external clock. Similarly, a recently published English study showed that postponing your breakfast and advancing your dinner by 90 minutes would help you lose fat.
The Salk Institute study is available here.
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