The Best Time of Day to Hit the Gym May Surprise You
How scheduling your workouts differently can incrementally increase the benefits you reap
Most people don’t think about the optimal time of day to train. The thought that there might even be an optimal time — one when the human body is biologically predisposed to do more work, burn more fat, and build more muscle — rarely even occurs to people.
Worse, when the subject does come up, the answer you’ll most often hear is that morning workouts are optimal because they burn more fat.
However, the research doesn’t entirely support that. In fact, when it comes to weight training, a growing body of research suggests that evening training blows morning workouts completely out of the water.
Research Is Clear: Evening Beats Morning
The argument for morning workouts being superior for fat loss is that because your glycogen stores are relatively depleted in the morning, you’ll burn more fat during a morning workout. And this is true, as far as it goes — morning workouts do acutely burn more fat for just that reason.
Studies have not consistently shown that training in the morning causes more weight loss or better performance over the long term. In fact, while the evidence is equivocal with regards to aerobic exercise, when it comes to resistance training, trainees perform better later in the day.
A 2014 study by Malhotra et al found significantly greater strength gains from early evening versus morning training. The difference was 29% vs 23% improvement for eccentric exercise (lowering the weight in a slow, controlled manner), with a more modest 23% vs. 21% improvement for concentric (raising the weight) exercise.
A 2016 study tested training in the morning between 6:30 a.m. and 10 a.m. against training in the later afternoon or early evening between 4:30 p.m. and 8 p.m. While there were no statistical differences in strength gains, the evening training group did gain more muscle mass.
The effects may be more pronounced the more advanced the trainee is. Another study performed on bodybuilders found that the evening group gained 3.2% fat-free mass, and lost 4% body fat, while the morning group gained only 0.6% fat-free mass and gained 5% body fat. While none of the results were statistically significant due to the small sample size, they are in line with the results of other studies.
In general, studies on resistance training by experienced trainees either find evening training to be superior or find no significant difference between morning and evening, but they rarely, if ever, find morning training to be superior. This may be because muscle anabolic signaling is stronger later in the day.
That said, there are several more specific mechanisms that likely explain the better results from lifting weights later in the day.
Why Afternoon/Evening Workouts Are Better
Reason 1: A better hormonal environment later in the day
In research, the testosterone/cortisol ratio is commonly used as a marker for exercise recovery and anabolic potential. The higher it is, the more your body is primed to build muscle.
Testosterone is, of course, a sex hormone that drives muscle growth, among other things, such as libido and body hair growth. While it’s thought of as the “male sex hormone,” women have testosterone too, and what follows seems to apply to women just like it does to men.
You may know cortisol as the body’s main “stress hormone.” Along with markers of systemic inflammation, it’s a good all-around measure of how much stress (both physical and psychological) and damage the body is dealing with.
After working out, testosterone goes down and cortisol goes up. In general, the faster they recover, the more muscle you’ll gain. Also, the higher testosterone and the lower cortisol are to begin with, the more muscle you’ll gain.
Cortisol follows a different pattern — it peaks in the morning slowly after waking, and goes down throughout the day.
Put these two patterns together, and your testosterone/cortisol ratio is at it’s highest when you sleep and is higher in the late evening that earlier in the day.
Since high levels of anabolic hormones and low levels of cortisol are associated with more muscle growth and better recovery from exercise, this supports hitting the weights later in the day. In fact, you may argue that it supports working out right before bed; however remember that these hormone levels are arguably more important after exercise, rather than during it. And of course, there are other factors to consider.
Reason 2: Core body temperature is higher later in the day
We’re used to thinking of human body temperature as being 98.6 degrees Fahrenheit. The truth is that human body temperature varies both between individuals and depending on times of the day.
Human core body temperature is at its lowest in the evening, rises quickly after awakening, and peaks in the evening. For the average adult male, sleeping body temperature will get as low as 97.5 degrees, while peak body temperature will be just over 99 degrees and will occur around 7–8 p.m.
This is important because core body temperature correlates with exercise performance.
Additionally, most people will achieve higher muscle activation levels in the evening vs. the morning. That means they can use — and fatigue — more of their muscle fibers, making workouts more productive.
Higher body temperatures also loosen up the muscles, allowing for more flexibility. The greater elasticity may be partially responsible for the increase in power later in the day.
Reason 3: Timing relative to meals and sleep
This part is a bit more speculative, but nutrient and sleep timing relative to exercise may play a role here as well. It’s well-known that both nutrition and sleep are crucial to recovering from exercise — could it be important that they come soon after your workout?
There is clearly a post-workout anabolic window in which the muscles are more able to absorb and use protein. How important this window is, and how long it lasts, is widely disputed, but studies do tend to find greater muscle growth when a particular effort is made to consume protein within a few hours after training.
As for sleep, not getting enough of it impairs muscle growth. As far as I know, studies haven’t yet looked at how soon after a workout you should go to sleep, but it’s possible that there’s a similar post-workout window here, in which you want to sleep relatively soon after your workout in order to quickly recover your sleep debt, since sleep debt decreases protein synthesis and muscle anabolic signaling.
In short, working out in the late afternoon or early evening may be optimal in part because it allows you to go to sleep relatively soon after training, while still giving you enough time for one or two good meals before bed. That is, the timing allows you to optimally satisfy both the need for post-workout nutrition and the need for post-workout sleep.
A Few Caveats
As with any kind of “what works better” discussion, the answer has to come with the qualifier “all other things being equal.” And of course, all other things are not always equal.
This is relative to when you wake up, not the clock
The studies and methods quoted above have all found an optimal training time somewhere between 3 p.m. and 9 p.m. That is not, however, an absolute.
In this case, timing matters relative to your biological clock; the exact time of day isn’t really the issue here.
The subjects in these studies were all sleeping on a fairly normal schedule, waking up around 6–9 a.m. and going to sleep around 10 a.m. –12 p.m. That corresponds to a training window between six and fourteen hours after waking up. In practice, however, the truly optimal training window — for most people, anyway — corresponded to a time period more like eight to twelve hours after waking up.
You have to do what fits your schedule
A good strength training workout takes time, and usually requires a gym — at least if you plan to lift heavy weights and perform a variety of exercises. That means you need at least an hour to spare, and often more.
Making the time to work out is at least as important as working out at the (physiologically) optimal time of day. It’s better to do a complete, hour-long workout in the morning with proper rest periods than a rushed, incomplete workout at 5 p.m.
That said, most people can make time somewhere in that optimal window, which again is pretty broad. When people “don’t have time” to work out, that almost always means they actually have the time and spend it on something else they value more. In other words, you “don’t have time” for something in addition to all the stuff you’re already doing.
Your stress levels have a huge influence on your ability to recover from exercise — the difference between high and low stress levels can easily equate to a twofold difference in recovery capacity and muscle-building potential.
Cortisol, the body’s main stress hormone, also causes the human body to store more belly fat. Thus, people who are training to lose fat are likely to be disappointed by the impact on their waistline if they train when they’re stressed out.
Some people have very stressful lives, and in particular, very stressful jobs. For people working a typical 9–5 schedule, training at the optimal time usually means, in practice, training right after work.
If you’re commonly stressed out at the end of the workday, this probably won’t be ideal. It’s better to exercise when your stress levels are lower, even if it’s a little outside the optimal training window.
Training later in the evening usually isn’t an option either — people with very stressful jobs usually don’t have the energy for it later in the evening and prefer to spend the whole evening relaxing. The big exception here would be if you do find exercise relaxing, particularly if your gym is also near your home, allowing you to unwind a bit after work before walking over to the neighborhood gym.
But for most people, this situation — being stressed out at the end of the workday — will necessitate training earlier in the day. Lunchtime would be preferable to early in the morning if you’re able to take a long enough lunch break and have a gym close to work.
At least one study shows that in shift workers, peak performance occurs earlier in the day. So it is certainly possible for your work schedule to shift your peak performance time. However, this only goes so far, as you’ll see in the next section.
While this is earlier than the optimal training window, there are a few ways to make earlier workouts more effective.
You can become entrained to your workout time
Over time, things you do at the same time every day become entrained into your circadian rhythm. You get tired before your typical bedtime. You get hungry before your usual meal times. And, fortunately, your energy level will start to rise in anticipation of your daily workout.
If you train in the morning, consistently, you will start to have more energy in the mornings and your morning workouts will become more productive. Almost anyone who trains in the mornings can attest to this — it’s hard at first, and gets easier over the first few weeks.
Of course, most people don’t train every day. In order to benefit from this entrainment effect, you’ll need to train fairly often — probably at least four days a week at the same time, i.e. training more days than not.
However, studies suggest that this adaptation is only partial. While training in the mornings may give you more energy in the morning, it might not shift your peak core body temperature to earlier in the day.
Fortunately, there is one other tool you can use to shift your biological clock.
Caffeine can make a difference
Caffeine, of course, raises your subjective energy level. And as I discussed in my article on gym motivation, caffeine also motivates you to work out more.
While caffeine’s effects are mostly psychological, it does also raise your core body temperature and levels of muscle activation during exercise, particularly when consumed during the morning.
In one study, people who trained in the morning after consuming 250 mg of caffeine (around 3 mg/kg) showed almost as much neuromuscular readiness to exercise as people who trained in the afternoon without caffeine. Their exercise performance wasn’t statistically different from the afternoon group; however, it was non-significantly lower across the board.
Unfortunately, the dosage of caffeine used in this study is high enough to be problematic. As I discussed in my article on caffeine addiction, taking more than 100 mg per day will lead to a gradual tolerance buildup and accompanying withdrawal symptoms.
Moreover, taking that much caffeine (even first thing in the morning) will impair your sleep later that night, up to 15 hours later.
It’s better, in the long run, to have around 100 mg of caffeine before morning workouts. Acutely, this won’t be as good as a higher dosage, but you’ll see better long-term results when you sleep well and don’t become addicted to caffeine.
What This Means For You
Here’s what I tell my clients: all other things being equal, you’ll be better off working out later in the day.
In more detail, adhere to the following guidelines to maximize the impact of your workouts:
- Schedule your resistance training (i.e. weightlifting) workouts at least six hours, and no more than twelve hours, after waking. For most people, this will be between 3 and 9 p.m.
- Cardio may be more effective in the mornings.
- If you do have to resistance train earlier in the day, consume around 100 mg of caffeine pre-workout to give you more energy and strength.
- Whatever time of day you work out, do it at the same time every day to become entrained to that workout time.
- If you train outside of optimal hours, also train at least 4 days a week to strengthen the entrainment effect.
- If you experience a lot of work stress and have no energy at the end of the workday, train either at lunch or before work and use caffeine as suggested above.
- Keep prioritizing getting a good night’s sleep. Not only is that important, but it’s largely what makes this work in the first place.
Do you have questions or comments about this article? A related study you’d like to share or ask me about? Share them in the comment section below.