Disrupting circadian clocks, which keep the body and its cells going through the 24-hour day-night cycle, can cause weight gain, two studies have found.
- Every cell in the body has an intrinsic cellular clock and there is a master clock in the brain which controls hormone secretion.
- Eventually, the development of drugs could help reset circadian rhythms in obese people.
Stress at the wrong time of the day (in the evening, when resting) can upset the metabolism and trigger weight gain, even if the diet does not change: these observations by Weill Cornell Medical College researchers on mice could help to develop new therapeutic approaches to obesity.
The latter have indeed shown that the circadian rhythm, defined by the alternation between wakefulness and sleep over 24 hours, plays a key role in the growth of fat cells.
Glucocorticoids
In a first study published in Cell Reports, Dr. Mary Teruel, associate professor of biochemistry and member of Weill Cornell Medicine’s Gale and Ira Drukier Institute for Children’s Health, and colleagues mimicked the disruptive effects of certain conditions on the usual daily fluctuations of glucocorticoids, a class of hormones related to stress. It was Cushing’s disease which is due to the production of cortisol – the stress hormone, in too large quantities, and chronic stress.
To do this, they implanted granules under the skin of mice that release glucocorticoids at a constant rate for 21 days and compared them to normal mice that exhibit normal daily fluctuations. As a result, the amount of brown and white fat in the mice given the glucocorticoid granules doubled in 21 days, and insulin levels in their bodies skyrocketed, even though the mice continued to follow the same diet. healthy than normal mice.
Break
A second study, published August 8 in the journal Proceedings of the National Academy of Sciences has shown that the cells become fat cells during a 12-hour window each day, corresponding to the time of rest. “The decision to become a fat cell occurs quickly within four hours. It’s like a switch and it only happens at a certain time of the daysaid Dr. Teruel.
Therapies targeting this famous window of the day could result from these discoveries in order to prevent the excessive accumulation of fat. Eventually, this could notably lead to the development of drugs that help reset circadian rhythms in obese people, as an alternative to more invasive treatments such as bariatric surgery to reduce obesity, which consists for example of the pose of a gastric band.