Now a new study shows great insight into exactly why this is the case. In particular, the study offers the first understanding, on a molecular level, of why people tend to gain weight due to chronic stress, disrupted circadian rhythms, and treatment with so-called glucocorticoid drugs. And the reason for it is simply that the timing of the "dips and rises" in glucocorticoids, particularly cortisol, has a large impact on weight management.
The study, which was conducted by a group of researchers from the Stanford University School of Medicine and published recently in the journal Cell Metabolism, suggests some new strategies that can be used to effectively reduce weight gain by way of controlling the timing of certain hormonal impulses. This is according to Mary Teruel, Ph.D., an assistant professor of chemical and systems biology and one of the senior authors of the study.
"It explains why treatments with glucocorticoid drugs, which are often essential for people with rheumatoid arthritis and asthma to even function, are so linked with obesity, and it suggests ways in which such treatment can be given safely without the common side effects of weight gain and bone loss," she said. (Related: Holiday Weight Gain: Stress, Not Food, is Primary Cause.)
Normally, fat cells are known to turn over at a standard rate of 10 percent per year. This means that they die and get replaced by newly differentiated fat cells. However, the actual mechanism as to why this is the case has remained unknown until now. Now, the circadian code that controls to switch is finally known, and the key molecules that are involved in it have finally been identified, said Teruel.
In their study, the research conducted a series of experiments. The first one showed that one pulse of glucocorticoids, which lasted 48 hours, led most of the fat cells to differentiate. Meanwhile, shorter pulses that lasted at least 12 hours between them didn't have a noticeable overall effect at all.
The researchers also tried to see if their ideas on the circadian rhythm worked on living animals. After a 21-day study on lab mice, they found that the loss of the normal circadian rhythm for glucocorticoids was linked directly to a doubling of the fat mass of the animal. In addition, they found that there was no increase in fat when they boosted glucocorticoids, delivered through injection, only while normal circadian peak times were occurring.
So far, the research has shown that it has many implications for weight management in humans.
"Yes, the timing of your stress does matter. Since conversion of precursor cells into fat cells occurs through a bistable switch, it means you can control the process with pulsing," Teruel explained. "Our results suggest that even if you can get significantly stressed or treat your rheumatoid arthritis with glucocorticoids, you won't gain weight, as long as stress or glucocorticoid treatment happens only during the day."
The findings may be clear, but applying the knowledge gleamed from them is a different matter entirely.
Learn more about the effects of stress to your overall health at Mind.news.
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