Pumped up actors and athletes are obsessed with early morning workouts: Dwayne "The Rock" Johnson gets up at 4 in the morning to visit his "Iron Paradise" gym. Former American Gladiator Mike O'Hearn posts about his early workouts almost every day.
Do you have to join these jacked dudes before dawn to get the results you want? When's the best time to train? Morning or evening?
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Should You Work Out in the Morning or Evening?
"The number one answer to it: When you can do it," says Alex Viada, CSCS, owner of Complete Human Performance. Committing to consistent training at a "suboptimal" time is better than sporadically training at the "perfect" time — consistency is key when it comes to results.
"That's what I think gets overlooked a lot of times — there's what's 'optimal' and there's what is real life," says Ross Edgley, author of The World's Fittest Book. "Just train. If you've got kids, and you've got to take them to school or something like that — just get your workout in" at whatever time works for your schedule.
Even if a busy schedule isn't a factor, your "optimal" time may be different from someone else's. For decades, scientists have studied chronotypes: scientific classifications for people who are naturally early birds (called "larks" in studies) and night owls.
In a seminal study from March 2001 in Chronobiology International, scientists found that the levels of cortisol, a stress hormone that makes it harder to build muscle, goes down more quickly in the morning for early birds.
So natural "morning people" may have less of this muscle-sabotaging hormones in their bodies if they work out first thing. But your levels will depend on your natural "morningness" or "eveningness."
Even with all this, there are some benefits to morning workouts — and some benefits to evening ones, too. Here's a breakdown so you can choose what fits best with your goals.
Benefits of Morning Workouts
1. Could Be Best for Consistency
In some studies comparing morning and evening workouts, like a small June 2019 study from Contemporary Clinical Trials Communications, morning exercisers were slightly more likely to complete their sessions than evening exercisers — morning exercisers did 94 percent of their sessions, compared to 87 percent for afternoon/evening exercisers.
That may not seem like much, but consistency is one of the most important drivers of workout success. And morning workouts driving consistency makes sense: If your workout's the first thing you do, it's harder for unexpected meetings and other events to derail your schedule.
But it's not an absolute. In most other studies comparing morning and evening workouts, exercisers completed their sessions at about the same rate. So hitting the gym with the dawn patrol isn't a guarantee of success.
2. Might Be Better for Weight Loss
In a small July 2019 study from the International Journal of Obesity, people who exercised in the morning lost more weight over 10 months than those who worked out between 3 and 7 p.m. The workouts they performed burned about the same number of calories, but the a.m. folks lost the most weight.
The afternoon exercisers had lower levels of "non-exercise energy expenditure," meaning they burned fewer calories when they weren't working out, which could be part of the explanation. Another March 2017 study in Clinical Obesity found that inactive women with overweight who worked out for 30 minutes in the morning lost slightly more weight than those who exercised in the afternoon.
Don't set your alarm just yet: The afternoon exercisers in the 2019 study didn't just burn fewer calories at rest; they also ate 80 to 230 calories more per day. So if you skip one slice of bread or a Snickers bar, you'll reap the same benefit from afternoon exercising as a morning sweat session.
Benefits of Evening Workouts
1. Could Be Better for Blood Sugar Levels
If you're worried about blood sugar control, afternoon exercise might have an edge. In a December 2020 study in Physiological Reports, afternoon exercisers who were at high risk for diabetes developed better blood sugar control than those who started exercising in the morning.
This echoes findings from a November 2018 study from Diabetologia that found that when people performed high-intensity interval training workouts, afternoon exercisers developed better blood glucose control. And morning HIIT participants actually experienced acute spikes of glucose that could be dangerous.
2. Might Be Better for Sprinting or Jumping
In a novel September 1998 study in Medicine and Science in Sports and Exercise, scientists had participants perform exercise at four different times of day: 8 a.m., noon, 4 p.m. and 8 p.m. Muscle performance was higher in the evenings but only during exercises that required explosive movement.
"It's believed that this is because the activation of fast-twitch muscle fibers perform far better when body temperature is higher," Edgley says. And body temperature tends to be higher in the evening than in the morning.
How Late Is Too Late?
As described in an August 2020 study from the International Journal of Exercise Science, when you exercise late in the day, it can delay your body's production of melatonin, a chemical that helps transition your body and mind to sleep. So if you exercise too late, you can start to impact how well you sleep — which can impact how well you recover.
"[Finish your training] within 3 or 4 hours of sleep — that's kind of a guideline," Viada says. "For a lot of people, though, it's unavoidable" that they'll train later.
If your only chance to work out is late, consider a melatonin supplement 30 to 60 minutes before bed. In a September 2018 study from Chronobiology International, taking a 10-milligram dose after a hard, late-night workout helped teen athletes sleep better than they did after the same workout with no supplement.
Talk to your doctor before adding any new supplements to your regimen, though, to make sure they don’t interact with any medications you’re currently taking.
If you have the luxury of picking any time of day to train — with no interruptions, no work schedule, and no other obligations —what would be the best time to train?
"For the most part, I would have most athletes work out at the same time of day every day," Viada says. Training at close to the same time each day lets you get used to how your body feels at that time, so you can "turn it on" for your workout.
But what time should that "same time every day" be?
"Well, if you train too early in the day, you have some issues with explosive strength and power. If you train too late in the day, you start to get interruptions with your sleep schedule," Viada says. "So for me, the best time of the day is really around midday. Your energy levels are good. You're warmed up. And you can go through a hard workout with plenty of time to eat, recover, and bring yourself down afterward."
That only works, of course, if it works for your schedule. And, Edgley says, if it feels best for you.
"For all the studies that talk about hormonal imbalances and everything like that, I think intuitively, a lot of people will just know," he says. "I love training first in the morning. I struggle a little bit at night … I think your body's trying to tell you something."
Science backs this up, too! In a January 2016 study from Health Psychology, people were most likely to do their workouts if they performed them when they felt naturally inclined to. These feelings and called "instigation habits" and can help push you toward your best time to work out.
Bottom line? Edgley says: "Go with your gut."
- Chronobiology International: "Circadian rhythmicity of cortisol and body temperature: morningness-eveningness effects"
- Contemporary Clinical Trials Communications: "The feasibility and acceptability of morning versus evening exercise for overweight and obese adults: A randomized controlled trial"
- International Journal of Obesity: "The effects of exercise session timing on weight loss and components of energy balance: midwest exercise trial 2"
- Clinical Obesity: "Comparison between the effect of 6 weeks of morning or evening aerobic exercise on appetite and anthropometric indices: a randomized controlled trial"
- Physiological Reports: "Exercise training elicits superior metabolic effects when performed in the afternoon compared to morning in metabolically compromised humans"
- Diabetologia: "Afternoon exercise is more efficacious than morning exercise at improving blood glucose levels in individuals with type 2 diabetes: a randomised crossover trial"
- Medicine and Science in Sports and Exercise: "Biorhythmic influences on functional capacity of human muscle and physiological responses"
- International Journal of Exercise Science: "The Effect of Timing and Type of Exercise on the Quality of Sleep in Trained Individuals"
- Chronobiology International: "Melatonin ingestion after exhaustive late-evening exercise improves sleep quality and quantity, and short-term performances in teenage athletes"
- Health Psychology: "Habitual exercise instigation (vs. execution) predicts healthy adults’ exercise frequency"