What Is the Best Time to Exercise?

Finding time to exercise is already an achievement in itself, given how busy our daily lives can be. But is there an optimal moment in the day to work out? A time when we’d have more energy, or a greater tendency to burn calories ? We did a little digging!

A shared biological rhythm

Human beings are both very different and very alike. But one thing is certain: we all share a broadly similar biological rhythm. Our body is governed by a kind of internal clock, located in the brain, in the hypothalamus. This means our body runs on a 24-hour cycle, which includes several phases — the two most obvious being sleep and wakefulness. During these phases, the hypothalamus manages all vital functions according to the body’s needs, regulating organ activity, blood pressure, hormonal secretions, breathing rate, body temperature, and more.

In the morning, for example, body temperature gradually rises, along with blood pressure and breathing rate. The hypothalamus triggers the release of cortisol — a hormone that wakes us up and gives us the drive to get out of bed and start the day.

Conversely, in the evening, body temperature tends to drop and the pulse slows. The hypothalamus, acting as a master conductor, signals the release of melatonin, a hormone that promotes sleep.

This biological rhythm, which fluctuates throughout the day, is worth taking into account. It can help identify which moments are most favourable for physical activity (energy peaks, better endurance), and also determine the best type of exercise to do at any given time.

Early morning

Fans of the “morning miracle” concept, along with some scientists, champion the benefits of exercising right after waking up. Some studies suggest that working out between 6am and 10am may:

Burn more fat, especially when exercising on an empty stomach⁽¹⁾, thanks to elevated cortisol and growth hormone levels in the blood.
Reduce appetite⁽²⁾. Morning exercisers may tend to eat less throughout the rest of the day.
Increase the likelihood of adopting a healthy lifestyle⁽³⁾. Healthy habits formed in the morning may be easier to maintain over time.
Offset the effects of a poor night’s sleep⁽⁴⁾, as exercise is a mood regulator and can help ease stress.

That said, some scientists and health professionals temper these conclusions:

There is currently no solid evidence that exercising on an empty stomach leads to greater fat oxidation or more significant weight loss⁽⁵⁾.
Upon waking, the body may need time to restart its vital functions, which slow down during sleep. It may therefore be wise to save intense, cardio-heavy activities for a later point in the day.
Morning exercise isn’t necessarily better than afternoon exercise — the effects are simply different. Muscles may metabolise fat and sugar more efficiently in the morning, but overall energy expenditure and the “afterburn effect” tend to be greater when activity is performed in the afternoon or evening⁽⁶⁾.

With this in mind, it may be worth shifting endurance or HIIT sessions to a slightly later time in the morning. And for those who love a run first thing, it’s worth having a small bite before heading out — not necessarily a full breakfast, but a drink, a couple of hard-boiled eggs and a banana could do the trick!

Late morning and late afternoon

The windows between 10am–1pm and 4pm–7pm are considered among the best times to exercise, particularly for endurance activities. During these periods, insulin levels tend to be at their lowest, as the previous meal (breakfast or lunch) will have been digested. The body therefore has enough energy to sustain intense effort and draw on its fat reserves.

As for physical performance, the research is again divided. Some studies suggest athletic performance is better when exercise takes place in the morning⁽⁷⁾, while others indicate that peak physical performance — in terms of power, endurance and flexibility — occurs in the evening⁽⁸⁾.

One thing is clear: endurance sports practised too late in the day — after 7pm — can have a negative impact on sleep quality. Exercise triggers a rise in endorphins and dopamine, which boost mood, but also stimulates adrenaline, leading to an energy surge, increased heart rate and higher blood pressure. In short: exercise relieves stress, but it also energises. Working out too close to bedtime could therefore make it harder to fall asleep.

So, what is the best time to exercise?

Quite simply, the best time is the one that works best for you! Of course, some moments are genuinely less suited to exercise:

Right after a meal, during digestion. Chances are you won’t feel like exercising then anyway!
Too close to bedtime, as explained above. If you do want to be active in the evening, opt for something more restorative — yoga, Pilates or gentle stretching are great options.

For everything else, let your body and your internal clock be your guide. You know better than anyone when you feel at your physical best and ready to push yourself. And remember: what matters most isn’t when you exercise, but how consistently you make physical activity part of your routine. The recommendations remain the same:

30 minutes of moderate physical activity every day — such as walking.
More intense physical activity 2 to 3 times a week, in sessions of 45 minutes to 1 hour — cycling, running, cardio…