Listen to your body

The next time you enter a waffle house in the early hours of the morning and order the Texas cheese and cheese melt (1,040 calories), think about this new finding: at about this time that is, the most basic operations of the human body about 10% of their caloric needs compared to the rate at which they will burn calories in the late afternoon or early evening.
Perhaps you prefer to return to dinner time.
This pattern of calorie use does not vary significantly depending on whether you are the waitress working in the cemetery or a stopover from 9 am to 5 pm for breakfast after eight hours of shutdown, the researchers discovered. The "resting energy expenditure" of the human being – the body's use of calories to supply basic functions such as breathing, brain activity and fluid circulation – follows a predictable cycle that stretches as the day progresses and decreases as night falls.
The new study, published this week in the journal Current Biology, offers further evidence that circadian rhythms dictate not only the need for sleep, but also the functioning of complex mechanisms such as metabolism over a 24-hour period. This may help explain why people who have irregular sleep schedules, including shift workers, have higher rates of obesity and are more likely to develop metabolic abnormalities such as type 2 diabetes .
And it shows that whether we hear it or not, our biological clock is always turning, placing us in our daily cycle with incredible precision.
At "zero hour" – which is approximately 4:00 to 5:00 am – our core body temperature drops to its lowest point and our standby fuel consumption reaches its lowest point. From that moment on, first quickly, then a little more slowly, the body's "energy expenditure at rest" increases until the end of the afternoon or early evening. After reaching its peak at around 17 hours, the number of calories we burn at rest gradually decreases for about 12 hours.
And then, just as surely as the day follows the night, we start again.
These new discoveries remind us that no matter how our schedules became 24 hours a day, our bodies were built for a slower and simpler world in which humans traveled all day in search of food, ate while the sun was up and sleeping when the sky was dark.
Today, our appetite and the availability of tempting dishes all night long can make us eat well after sundown. And our jobs may require us to sleep the day and wait at the table, treat patients, or drive trucks all night long. But our bodies still adhere to their old, inflexible clocks.
The results of the study are also accompanied by an implicit warning: when we do not take into account the biological rhythms that govern our body, we do so at our own risk.
The energy expenditure at rest represents the majority of the minimum calories that we burn during a day. Spending a day eating, sleeping and breathing consumes 60% to 70% of our "energy expenditure at rest". Thus, a serious imbalance between calorie consumption and the burning of most of them could prompt the body to make decisions – like storing calories in the form of fat – that are not necessarily healthy.
The new study adds to a growing body of evidence suggesting that a good 12-hour fast, when the darkness and nocturnal response of our body are aligned, can be a way to prevent or reverse obesity. Satchin Panda, a researcher at Salk Institute, has demonstrated the impact of food obedience on our circadian rhythms in laboratory animals and a growing number of people.
Others have demonstrated the power of timing by showing how quickly it can be disrupted.
In a study conducted in 2014, 14 healthy and skinny adults agreed to upset their days over a six-day period. Fed with a diet sufficient to maintain their weight, the subjects quickly adapted by lowering their thermostats. Compared to basic readings taken on arrival (when they were awake during the day and asleep at eight o'clock in the evening), the subjects burned 52 fewer calories on day 2 of their rotation program and 59 calories less on day 3 of this program. .
Do it for a few days and you may feel a little behind. Do it for months, years or a lifetime, and the result could be an excessive accumulation of stored fat and metabolic processes that go awry.
"One of the things to remember is that for optimal health, including metabolic health, it's best if we have a regular schedule seven days a week – we get up and go to bed at the same time and have our meals at home. same time, "Jeanne F. Duffy, senior author, neuroscientist and sleep specialist at Brigham Hospital & Women's Boston Hospital.
"We have these powerful clocks in us and they are ready to deal with certain events – eating and sleeping – at particular times of everyday life. We want them to be perfectly prepared for that.
To achieve these results, the researchers had to convince seven people to spend three weeks sequestered in windowless rooms without a clock, cell phone or Internet service. In what is called a "forced desynchronization protocol", the researchers extended the four-hour subjects' days. All spent at least eight hours in bed at the end of the day, then woke up and went through an artificial "daylight" period of 18 hours before they could sleep again.
At first, they seemed to run to follow this strange clock. But after three weeks of such discombobulation, the subjects rely essentially on their own internal clocks to set the length of their days and separate their days from nights.
The individual rhythms in which each subject fell did not show much variation: without a wake-up call or other signal, they finally regained their sleep and waking cycle that hovered around 24 hours, Duffy said.
By the end of the first week, the structure of their hourly resting energy expenditure had become clear: in the space of 23 hours to 24 hours, subjects disconnected from the daytime and nighttime signals displayed patterns. use of resting energy that were remarkably similar, and which followed the same increase of the day and the same decline of the night. These trends remained unchanged until the end of the third week.
Similar patterns of macronutrient use have also been observed. The subjects burned most carbohydrates at the beginning of their waking hours. Carbohydrate consumption then decreased steadily, with a small jump in the middle of the night. Fat burning was lowest in the morning, peaked in the early evening and then decreased.
"We were impressed by the fact that these models were so similar between individuals," said Duffy. "It told us that it was something real."
The number of calories we burn – or store as fat – is probably influenced not only by our size, what we eat and the amount of exercise we get, Duffy said. The timing of eating is also important.
When we sleep late at weekends, whether we are talking about time zones or working on schedules that keep us up all night, then back to the day, "we disrupt our clocks and make our metabolisms inefficient and, in the long run will lead to illness, "she said. "The best way to avoid this is to stay on the same schedule." – Los Angeles Times / TNS