Running in the background of your physical and mental processes is your internal clock, also called your circadian rhythm, which creates cycles of time that inform when you sleep and wake.
But you don’t have only one clock. Although there’s a “master clock” at work, each organ has its own timing, research has noted. For example, a recent study found your liver’s circadian clock can detect light, thanks to signals from other organs. That kicks off numerous processes related to liver function.
Similarly, circadian rhythms can play a role for your heart, regulating aspects of cardiovascular health like blood pressure and heart rate.
When all of these clocks are working in harmony, you can often feel it — that sensation of being in sync — but you may also sense when there’s misalignment, too. When that happens, it could be the culprit if you’re struggling with weight loss.
One way experts suggest to synchronize your clocks is to keep a regular schedule, which puts everything in sync. This applies not just to sleeping and waking — although that’s crucial — but also making sure to take work breaks to de-stress, eat on a consistent (but not rigid) schedule, and exercise at about the same time each day.
As your circadian rhythm gets better established and aligned this way, it can pay off in weight loss as well, says Dr. Darria Long Gillespie, an assistant professor of medicine at the University of Tennessee.
That’s because resetting your body clocks in meaningful ways can significantly affect hormones, especially the ones like insulin, leptin, ghrelin and cortisol — which all play a part in weight gain and loss, as well as how you store fat and when you feel hungry.
“When you find that you’re trying to lose weight and it’s not working, hormones are often the reason,” she says. “If your circadian rhythm is off, your hormones will go into overdrive to try and achieve balance and get you aligned again. But the result can be sluggish weight loss or even weight gain.”
Looking for the first step to get your clocks right? Get moving. Research has suggested circadian clocks in the muscle tissue regulate the adaptations to changes in the environment and that workouts could be most efficient when done during daylight.
Although that study was done on mice, more recent research at Arizona State University on people underscored the advantage of a daylight-style exercise routine, especially because it provided energy not just when you work out but also the following day.
In that study, researchers found exercise at 7 a.m. or between 1 p.m. and 4 p.m. advanced the body clock enough that people could start activities earlier the next day. By contrast, exercising in the evening between 7 p.m. and 10 p.m. delayed the body clock, which means individuals had a harder time getting to peak-performance mode until later the next day.
Having more energy tends to boost motivation and physical activity, so there can be a ripple effect on health, says study co-author Shawn Youngstedt, PhD, a professor in the Arizona State University College of Nursing and Health Innovation.
“Exercise, like sleep, can do wonders for the circadian rhythms of the body,” he says. “If you couple that with other strategies that help, like getting natural light and spending time outside, it can be even more beneficial.”
One part of the potential weight-loss ripple effect from exercise is resetting the clock in your gut.
When the circadian rhythm in your digestive system is off, it can result in low energy, high appetite and disrupted sleep, which can all contribute to weight gain or slowed weight loss. Exercise, along with healthy eating, can greatly benefit the way your gut’s body clock works because it gets your serotonin on track, says Youngstedt.
A hormone and neurotransmitter, serotonin is usually highlighted for its feel-good action on your mood, but it’s also involved in sending messages between nerve cells in the brain. And 90% of serotonin is made in the gut. Much like the other hormones related to weight loss and gain, when serotonin is off, it can sabotage your effort to regulate weight.
Without gut microbial balance achieved through habits like regular exercise, healthy eating and proper sleep, you may get into what researchers call “circadian misalignment.”
“The more you establish habits that make you feel in sync, the more likely you are to be synchronizing the different aspects of your body clock,” says Youngstedt. “And good habits stack on top of each other; they can all have a beneficial effect.”
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