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​What single thing in your life:

  • Burns away fat
  • Makes you mentally sharper
  • Builds muscle to make you look sexy
  • Enhances blood sugar control
  • Lowers inflammation
  • Improves your sleep
  • Improves your cholesterol profile
  • Lowers your risk for cancer
  • Fights constipation
  • Strengthens your bones
  • Sweats away internal toxins
  • And builds stamina and circulation?

It isn’t sleep or an expensive supplement. The answer is regular exercise. So, the next time you think about skipping your workout, think about all these benefits and then think again!

Exercise plays a critical role in all aspects of our lives.

Yet, what might be the best time of day to exercise?……..For decades, I have exercised first thing in the morning because it was when it was most convenient. And importantly, this was when I was able to best control my time and avoid interruptions.

But, is first thing in the morning really the best time physiologically to exercise?

Recent research now suggests that our circadian clock and our ability to burn energy and control blood sugar levels are tightly intertwined.

A circadian rhythm, or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. Circadian rhythms are mostly affected by light and darkness and are called the “body’s clock.”

This master clock is composed by a group of about 20,000 nerve cells (neurons) within the hypothalamus of our brain, which receives direct input from the eyes regarding dark and light.

For decades we have understood that our circadian rhythms control when the best time is to go to sleep and wake up. Over the last few years, scientists have discovered that we have better blood sugar control by eating the same high-carb meal in the afternoon or early evening instead of the morning. More recent research now suggests that this clock determines when we should exercise as well.

Recent findings show that exercising in the afternoon lowers blood sugar more than the same workout first thing in the morning.

In August 2021, a study was published by Physiological Reports that compared the impact on blood sugar control from exercise in the morning to exercise in the afternoon. Over 12 weeks, researchers analyzed blood sugar control of 32 adults with type 2 diabetes who either exercised in the morning or the afternoon. Participants in the study combined aerobic-type and resistance-type exercises with three sessions per week.

Keep in mind that combining both aerobic and resistance-type exercise together is the best approach for blood sugar control as well.

They noted that the afternoon workout was more effective than the morning workout for critical markers of metabolism, including:

  • fasting blood sugar control
  • improved insulin sensitivity
  • and a drop in fat mass

In this study, in people with diabetes, the afternoon workout was clearly the winner.

Newer studies will soon be published that analyze blood sugar response to time of exercise in healthy adults—not just those with diabetes, with a larger, randomized sample size of subjects.

If you have the choice, schedule your workout in the mid-afternoon for the best results. However, if your schedule does not allow you to work out in the afternoon consistently, pick whichever time is best for you.

From ongoing research, we know convincingly that daily exercise is greatly superior to no exercise.

The key take-home message is to exercise daily, and if mid-afternoon works well for you, then that is the optimal time to work out.

I wish you the best of health!

Steven Masley, MD


Mancilla R, et al. Exercise training elicits superior metabolic effects when performed in the afternoon compared to morning in metabolically compromised humans. Physiological Reports 2021;8/e14669 


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