Internal biological clocks, or circadian rhythms, are 24-hour cycles that govern the behavior of living things. Scientists are finding more and more evidence that disruptions to this timing in humans can influence diet and sleep and lead to obesity, stress, metabolic disorder and possibly even cancer. What’s more, evidence increasingly points to ways to improve health and maintain weight loss by taking advantage of these circadian rhythms.
Humans evolved to hunt and forage during the day and sleep at night, meaning that human biology is designed to support eating and activity during the day and cellular repair and cleanup at night, according to Salk Professor Satchin Panda. But modern society offers access to food 24/7. These changes in eating patterns affect how the body processes food and functions.
The Salk lab previously demonstrated that confining mice to time-restricted eating during a ten-hour window can protect against obesity and diabetes. These groundbreaking studies have launched a new approach to potentially improving human health: restricting one’s calorie intake to an 8- to 10-hour window could confer a host of health benefits, including weight loss.
Recently, the team published the results of a small clinical study (with UC San Diego) in the journal Cell Metabolism showing that a 10-hour time-restricted eating intervention for people with metabolic syndrome, when combined with traditional medications, resulted in weight loss, reduced abdominal fat, lower blood pressure and cholesterol, and more stable blood sugar and insulin levels. Participants used an app developed by the lab and available to anyone at www.MyCircadianClock.org to help track the timing of their food intake, sleep and exercise.
“We have found that combining time-restricted eating with medications can give metabolic syndrome patients the ability to better manage their disease,” Panda shared with GB Magazine. “Unlike counting calories, time-restricted eating is a simple dietary intervention to incorporate, and we found that participants were able to keep the eating schedule.”
The team has also pursued studies around cancer and circadian rhythm. In January 2018, the lab published a paper in the journal Nature, describing how targeting the circadian clock in cancer cells could work as a therapy. Cancer cells disrupt their cellular clocks so they can get nutrients all the time to support their unchecked growth. The team found that when drugs are used to reactivate the circadian clock in tumors, cancer cells can’t survive. Meanwhile healthy cells are unharmed because they are already accustomed to following the clock.
“Eating and drinking everything (except water) within a consistent 10-hour window allows your body to rest and restore for 14 hours at night. Your body can also anticipate when you will eat so it can prepare to optimize metabolism,” says Emily Manoogian, a postdoctoral fellow in the Panda lab.
Currently, Panda, Manoogian and others in the lab are conducting a larger time-restricted eating study with metabolic syndrome patients as well as one with firefighters, who, like other shift workers, are at higher risk for chronic diseases because of how their schedule disrupts the body’s circadian rhythms.
To learn more about this field of research and listen to an interview with Manoogian, check out the Where Cures Begin podcast on www.salk.edu/podcast, iTunes or other podcast platforms. For more information about the Salk Institute, please visit: www.salk.edu.