We Decoded the Best Time To Work Out, According to Science

You might have heard your favorite Peloton instructor say that the best time to work out is whatever time you’ll actually work out. Read: There’s no point in setting that 5 AM alarm if you know in your heart you’re going to snooze, or on planning to take an evening class if you know you’ll struggle to feel motivated after a full day of work and family responsibilities.

But how do you know what the best time to work out is for you, and does that change depending on whether your fitness goals are to run a faster mile, build muscle, or kick-start weight loss? Does the best workout time depend on whether you’re a morning person or a night owl? Believe it or not, timing may be everything when it comes to endurance, strength, muscle growth, weight loss, and all of the other benefits you’re hoping to reap from exercising. To find out more, we went straight to the experts. Here’s how to decode when is the best time to exercise, no matter what your goal is.

How Your Biology Impacts the Best Time to Work Out

Your best workout time is largely impacted by your body’s circadian rhythm, which influences daily activities from sleeping to eating to—yep—exercising. On top of that, our chronotypes (whether we’re early birds or night owls) and our biological sex also play a role, since both influence body temperature, hormone levels, and preferred exercise times. 

“The combination of circadian rhythms and chronotype with the timing and mode of exercise appears to have a significant impact on the health and performance benefits we derive from the exercise,” says Paul Arciero, MD, a professor of Sports Medicine & Nutrition at the University of Pittsburgh and a professor of Health & Human Physiological Sciences at Skidmore College, who recently published some surprising data on this topic. “In our study of 50 men and women, we directly compared the physical and emotional performance benefits of exercising either early in the morning or evening—and we were surprised to find such a drastic difference between the groups, especially because they were all performing the exact same exercise routines during the 12-week study.” (We’ll get into the results of his study in a bit.)

So yes, to an extent, the best time of day to work out depends on your unique (and unchangeable) biology. However, your chronotype and circadian rhythms don’t have to be the end-all, be-all deciding factor in when you hit the gym. There’s much more to consider when planning your ideal fitness schedule—let’s get into it.

How to Determine the Best Time to Work Out for Your Fitness Goals

Your body will reap the benefits of exercise no matter what time of day it is. But while there really is no wrong time to exercise, there are advantages to be had at different times of the day, depending on your schedule and workout goals. So, what’s the best time to exercise? We’ve broken it down below based on various fitness goals—and we’re not exaggerating when we say that this information just may change your life.

The Benefits of Morning Workouts

Rise and shine! If you’re looking to lose weight, target visceral body fat, and more, morning workouts are where it’s at, especially for women, according to Dr. Arciero’s research. So when that alarm goes off and you’re considering hitting the snooze button, remember that workout will be totally worth it.

Your Fitness Goal: Weight Loss and Reduced Belly Fat (Women)

Perhaps the most startling result of Dr. Arciero’s study was just how much more women responded to morning workouts between 6 AM and 8 AM when it came to these goals. “Specifically, women who exercise in the morning have much greater loss of total body fat (-5 percent vs. -2 percent) and belly fat (-10 percent vs. -3 percent),” says Dr. Arciero, who published these results in Frontiers in Physiology in 2022. Their blood pressure was also significantly reduced compared to women who performed the same workout at nighttime. (Men saw better results with these fitness goals in the evening hours, which we’ll get into later.) 

Dr. Arciero details the best time to work out for weight loss and reducing fat in his book The PRISE Life, but here’s a brief overview: “I recommend for women to perform ‘intervals’ in the morning to optimize fat burning and then ‘resistance’ in the evening for ideal muscular performance and function.”

Your Fitness Goal: Sticking with an Exercise Routine

You know how it goes: You have the best intentions of exercising, but the later it gets, the more chances there are for that plan to go off the rails. You might have to work late, there might be tempting happy hour plans, the kids might have a bunch of activities, and you might just be exhausted after a long day. But in the morning, you don’t run the risk of life getting in the way, and studies show there’s a good chance you’ll be more consistent in exercising and creating good habits. According to a study of overweight individuals published in Exercise and Sport Sciences Reviews in 2020, morning workouts helped participants stick to their workout plans and lose weight. 

Morning workouts can also be key if you’re trying to make working out a habit, which may take around 66 days, according to research. And it’s best to build habits when your mind is fresh and uninhibited from the stressors that come along as the day progresses. In addition, cortisol concentration is higher in the morning, and cortisol levels have been identified as a significant mediator in the development of healthy habits. Training your body and mind to wake up in the morning and complete your workout could be the key to consistency that helps you form an unbreakable and life-changing habit of putting your health and fitness first.

One last bit of food for thought: Perhaps since other data shows that women who work out in the morning lose more weight, these noticeable results further boost motivation and the desire to stick to it. While that hasn’t been scientifically proven, we can certainly see the allure and think, at least anecdotally, that there may be something to it.

Your Fitness Goal: Decreased Hunger

If weight loss is your fitness goal, morning exercise can act as a natural appetite suppressant. Morning workouts may make you less ravenous later in the day—or at least less tempted by pictures of mouthwatering food, according to one study in the journal Medicine and Science in Sports and Exercise in 2012. (Psst: Keep in mind that hunger is a natural cue from your body, so remember to tune into your needs and refuel with protein after your workouts!) 

A more recent 2022 study by Stanford researchers may have figured out the reason for this phenomenon: an “anti-hunger molecule” (aka lac-phe, a hybrid of lactate and phenylalanine) released during certain types of exercise. While these scientists didn’t look at this molecule in relation to the best time of the day to exercise, it stands to reason that morning exercise could have a positive ripple effect on your appetite over the course of the day. One important thing to note: The intensity of your workout seems to be linked to how much lac-phe you produce—and how hungry you are afterward. That means you may need to work out at a higher intensity to achieve this effect.

How to Find Morning Workout Motivation

There are benefits to starting the day with a workout, even if you sometimes need to hit snooze a couple times before you're ready. But how do you motivate yourself in the morning? Peloton instructor Andy Speer suggests creating the habit with small, gradual changes. “Forcing yourself to wake up early will eventually lead you to get to sleep earlier. It may take a few days, but it will happen,” he says. “Start with easy morning workouts, routines you are familiar with and that are not too intense, and change one major variable at a time. Once you feel better about getting up and working out early, then add intensity and variety.” And if you unexpectedly stay up too late and snooze your alarm too many times, that’s okay—there are certain cases where it makes sense to prioritize sleep over fitness.

The Benefits of Afternoon Workouts

If you can sneak out of the office in the middle of the day, your work might actually improve—and you just might improve your longevity. Here’s what fitness goals pair best with an afternoon workout slot.

Your Fitness Goal: Improved Heart Health and Longer Life

We all know that exercise can help us live longer—but these effects exponentially increase with an afternoon workout. A seven-year U.K. study of more than 92,000 men and women published in Nature Communications in 2023 found that people who worked out between 11 AM and 5 PM were less likely to die prematurely of heart disease or other causes (with the exception of cancer) than those who exercised outside that window. While this benefit was seen across the board in this study, benefits for men and the elderly were more pronounced.

Your Fitness Goal: Increased Focus and Brainpower 

The drudgery of your day can take its toll, and a midday workout can give your brain the break and boost it needs (post-lunch crash, who?). The rush of workout-induced endorphins can beat any sluggishness you may feel, improve your mood, provide energy, and support cognitive function so you can finish your day strong.

“Several studies have shown that older adults who exercise in the afternoon tend to have better memory and reaction time following this exercise and more overall if the exercise is done routinely,” says Matthew Buman, PhD, director and professor of Health Solutions at Arizona State University. One of these, a study published in the British Journal of Sports Medicine in 2020, showed afternoon exercise helped with working memory and executive functioning. 

“Exercise can promote brain neurogenesis (i.e., growth of new cells) and improve the function synapses between brain regions,” Buman explains. “Since some older adults may have some decline in their cognition, we tend to see more pronounced effects of exercise in this group.” He adds that trained athletes who exercise at high intensities can show immediate cognitive benefits as well, though he’s quick to point out that everyone can benefit in this regard.

“For many, the immediate events might not be noticeable, but over the long run, these benefits can prevent dementia and improve many other aspects of health,” Buman says, “and this is the case regardless of what time of day the exercise is performed.”

Your Fitness Goal: Improved Performance

If you’re a regular on the Peloton Leaderboard and love tracking your improvements with data, an afternoon workout may be the best time to work out. While you’ll still want to do a quick warmup, the beauty of an afternoon workout is that your body has already been up and moving, so you’ll be more limber. No tight morning muscles here! And, if you’re planning an afternoon workout, you can be more strategic as you’re moving around in the morning—focusing on warming up the muscles you’re planning to work later. You can do calf raises while waiting at the printer, arm stretches after sending an email, or perhaps even a few jumping jacks every time you stand up from your desk.

You’re also more likely to set your PRs in the afternoon. A review of studies found that muscle strength, muscle power, and sprinting abilities all peaked in the afternoon, topping morning performance by anywhere from 3 to 20 percent. Plus, if you know you only have 60 minutes—or less—to complete your workout, you’re going to push yourself to make the most of that time. 

How to Fit in a Midday Workout

While some people prefer a more leisurely lunch hour, others find a midday workout helps reset their brain and gets them ready to power through the mid-afternoon doldrums. The trick, of course, is clearing your schedule and having enough energy.

That's why Andy recommends you make sure to be well-fueled and hydrated, because it can be easy to forget to eat or drink during the workday. But it's also important to make sure you aren't exhausted well before you clock out, so don't push too hard too often. “Plan your highest-effort days once or twice per week; the other days focus on quality and technique,” Andy explains. “Weights and moderate cardio tend to be less draining than HIIT classes.”

Be sure to warm up too, even if it's just for five minutes, especially if you've been sitting all morning. Save extra time by having your workout picked out and downloaded; that way, you’re not stuck scrolling for hours to find the exact right playlist or theme. Don’t forget to take advantage of filtering so you can narrow down workouts that actually fit the time you have available. As much as we’d love it, our busy days can’t always accommodate a 45-minute workout—but exercise snacks, on the other hand? Yes, please.

Finally, prep your mind to switch to workout mode so you’re ready to go at a moment’s notice. “Treat your workout time like a meeting,” Andy says. “Block the time out the same way. Also, don't judge yourself negatively if work thoughts flow in and out of your mind. Let the magic of the workout positively affect your thoughts. Don't fight it!”

The Benefits of Evening Workouts

If you’re not a morning person and your jam-packed afternoons aren’t conducive to workout sessions, you might gravitate toward exercise later in the day. And that’s a particularly good thing for men looking to lose weight and improve their cholesterol levels, as well as both men and women who want to build muscle. Here’s what the research shows.   

Your Fitness Goal: Weight Loss and Reduced Visceral Fat (Men)

According to Dr. Arciero’s study, men lost more weight and eliminated more visceral fat (that is, the deep, internal body fat that surrounds your vital organs) when they worked out between 6:30 PM and 8:30 PM. Just how much? Men burned 6 percent more fat in the evening hours compared with just 1 percent in morning workouts. Those nighttime workouts also lowered systolic blood pressure, cholesterol levels, and feelings of fatigue. 

Your Fitness Goal: Strengthening Muscles

“There is substantial research showing that evening resistance training can promote greater muscle growth,” Buman says. “This is largely because the hormones that are released to build muscle are typically secreted during sleep, so timing resistance training in the evening can optimize muscle growth.” 

Dr. Arciero’s study backs this up. He found that evening exercise for women resulted in a significant increase in upper-body muscle strength (16 percent vs. 9 percent), power (37 percent vs. 8 percent), and endurance (40 percent vs. 25 percent) when compared with morning exercise. As a result, he recommends resistance training in the evening, with endurance and stretching routines that can also enhance sleep and help your body recover from morning fat-loss workouts.

Your Fitness Goal: Lowering Blood Sugar

If you have type 2 diabetes, pre-diabetes, or simply deal with ricocheting energy levels and blood sugar spikes throughout the day, nighttime exercise may be your best bet, though exercising in the afternoon is a close second. In a study of overweight men and women in the Netherlands, published in the journal Diabetologia in 2022, researchers found that exercising between noon and midnight reduced insulin resistance as well as liver-fat content. Breaking it down further, exercising between 6 PM and midnight yielded a whopping 25 percent reduction in insulin resistance, while exercising between noon and 6 PM resulted in an 18 percent reduction. The ideal intensity? Moderate to vigorous. 

Beyond this, as the Cleveland Clinic notes, it’s important to keep the timing of your meals in mind if you have type 2 diabetes. They recommend exercising about 30 minutes after beginning your meal, referencing a 2017 study in Frontiers in Endocrinology. It’s also worth noting that after-dinner exercise has been shown to reduce triglyceride levels. 

How to Make the Most of Evening Workouts

If evening workouts are when you are most motivated (or when you can make the time), ensure that you're stretching sufficiently after every workout to avoid morning stiffness, and also be conscious of the recovery time between your workouts. “Doing an intense evening workout followed by an intense morning workout may not be ideal for recovery,” Andy says. “If you have to, extend the warmup in the morning session. Keep the intensity high, but shorten the actual workout.”

Then, of course, there's the challenge of winding down. Night exercise can lead to difficulties falling asleep because it can suppress melatonin levels. “Working out is waking up your nervous system,” says Andy. “It turns on your sympathetic system (fight or flight), [so] your body is still waiting to do the next sprint or pushup.”

To avoid tossing and turning, “Take 15 minutes to stretch, breath or do an easy yoga flow,” Andy says. “The point is to turn on your parasympathetic nervous system to rest and recover. Finishing a hard workout, showering, and going right to sleep without cooling down is not ideal.”

What About Exercise and Sleep?

Conventional wisdom holds that working out too close to your bedtime will rev you up too much to have a good night’s sleep. Science, however, tells a different story—sort of. 

First, the case for morning workouts as a way to improve your sleep: By training your body to expect a workout first thing in the morning, you’re more likely to develop the types of healthy sleeping patterns your body should be relying on. Specifically, research shows that exercise can help to regulate melatonin production, improving sleep quality. By embracing your body’s natural circadian rhythm of rising and moving with the sun, your body will be more primed to rest when the lights have gone out—and your sleep quality should improve as a result.

On the flip side, if you’re naturally a night owl, don’t stress too much about moving your workouts to the evening hours. According to a recent study published in Sports Medicine, working out at night actually increases the amount of slow-wave sleep, the deepest type of sleep. This is “particularly [true with] high-performing distance runners and other endurance athletes who exercise later in the day or evening,” Buman says. “They have been shown to have more restorative sleep later that evening.” 

This might be about finding the sweet spot in your exercise: a moderate workout that’s not too intense and ends at least an hour before you’re going to turn in. Because exercise releases endorphins and elevates your body temperature, your body needs a little time to return to normal before you drift off to dreamland. (You can also wind down with a sleep meditation.)

So, TL;DR? There are pros to working out in the morning and working out in the evening as it pertains to your zzz’s. Again, the most important thing is making time for movement, whenever it works for you.

The Takeaway

Everyone has different exercise goals, and by finding the best time to work out, you just might be able to reach them faster and more efficiently. But while there may be a “best time” to exercise for those fitness goals, the real key is to exercise consistently and, ideally, most days of the week. 

“For many, the most important factor to pay attention to is the time of day that will help you form a routine that you can stick with for the long run. There is certainly not a wrong time to exercise,” says Buman. “Exercise improves just about every organ and system in the human body, and this is the case regardless of the time of day. So find a time that works for you, and stick with it!”

When you’re crunched for time, Andy has a simple strategy to maximize the time and energy you do have.

“Do the most important element either first or when you feel the best. If you are more likely to skip running at night, then put it in the morning and lift at night, or vice versa. Bottom line, make your training work within your routine.” 

Plus, the beauty of working out consistently is that you don’t have to do it at the same time every day. Even highly extensive research concludes that while the body’s response to exercise does vary according to the time of day and alignment of circadian clocks, the optimal exercise time to elicit a desired metabolic outcome is not fully defined. There’s no perfect formula or time slot you need to force yourself into aligning with. You can even switch it up and get your workouts done during your lunch breaks on weekdays and then do longer, more thorough morning workouts on the weekend. The most important thing is that you’re getting your fitness goals accomplished, no matter what time of day they’re happening.