Best time to workout: morning, lunch or evening for a full diary

What the studies actually compare

Most time-of-day studies take one group that trains in the morning and one that trains in the evening, then compare their progress. The answer is consistent: both improve, and by similar amounts. Bruggisser's meta-analysis also found a high risk of bias in most of the studies, so even the small differences reported should be read cautiously.

The more robust finding is about matching. You perform best at the time you usually train. Grgic's review showed that people who trained in the morning raised their morning strength to the level they had in the evening. The body adapts to the hour you give it. That is good news for anyone whose only option is 6:30.

By goal

• Strength and muscle: any time. Gains are similar morning and evening, and morning trainees catch up on morning strength.
• Sprints, jumps and power: a slight edge between 16:00 and 20:00, according to a 2020 review by Mirizio and colleagues. An active warm-up, a warm room and training regularly at the same hour all reduce the gap.
• Endurance and health: the weekly total matters more than the hour. How much exercise per week gives the targets.
• Weight loss: unsettled, as the next section explains.
• Habit: a fixed time helps. Gardner, Lally and Wardle report that habits form through repetition in a stable context, taking about 66 days on average in one study.

Morning or evening for weight loss

The evidence conflicts. In a secondary analysis of a ten-month supervised programme, Willis and colleagues found that people who mostly exercised between 7:00 and 11:59 lost more weight, 7.2%, than those exercising between 15:00 and 19:00, who lost 2.1%. But participants were not assigned to a time; the groups were formed afterwards, with about 20 to 25 people each.

A retrospective comparison by Mancilla and colleagues pointed the other way. In 32 men at risk of type 2 diabetes, afternoon training improved insulin sensitivity and fat mass more than morning training. Neither design can settle the question. A randomised trial, TIMEX, with 128 adults, is under way and has not yet reported. Until it does, choose your hour for practical reasons.

Sleep and late sessions

Evening training does not generally ruin sleep. A meta-analysis by Stutz and colleagues found no harm from evening exercise, with one caveat: vigorous exercise ending an hour or less before bed might delay sleep and reduce its quality. A review by Frimpong and colleagues found that high-intensity sessions ending two to four hours before bed did not disturb healthy good sleepers.

Coffee is the hidden cost of very early sessions. A meta-analysis by Gardiner and colleagues suggests a standard coffee at least 8.8 hours before bed, and a pre-workout supplement at least 13.2 hours before. A 6:00 pre-workout drink is fine for a 22:00 bedtime; one at 17:00 is not. The guide to cortisol and exercise shows how these timings fit the body's daily rhythm.

The body clock and jet lag

Exercise also moves the body clock. Laboratory work by Youngstedt and colleagues found that exercise at 7:00, or between 13:00 and 16:00, advanced the clock, while exercise between 19:00 and 22:00 delayed it. For someone who sleeps late and wants to wake earlier, morning or early-afternoon sessions push in the right direction. After a flight, the timing of your session can help or hinder adjustment, as jet lag and training explains.

Dubai: heat and Ramadan

From 15 June to 15 September, UAE law bans work directly under the sun in open places between 12:30 and 15:00. The rule is for workers, not leisure, but it marks the hottest window clearly. Outdoor sessions in summer belong early in the morning or after sunset, and the midday slot moves indoors. Training in the heat in Dubai covers hydration and acclimatisation.

During Ramadan, private-sector working hours are reduced by two hours a day, which often frees a window in the afternoon or evening. For those fasting, sessions usually move to after iftar. See Ramadan and training for the details.

Choosing your window, step by step

1. Map the fixed points. Wake time, first meeting, last meeting, bedtime, on a typical day.
2. Measure the windows. Morning: from an hour after waking to the first meeting. Evening: from the last meeting to two hours before bed.
3. Take the larger one, if it is at least an hour. If both are too short, use lunchtime and a morning workout routine of twenty minutes on lighter days.
4. Fix it in the diary as a recurring meeting, at the same hour each day you train.
5. Plan a fallback for travel days, such as the hotel room or a walk between meetings.
6. Review after a month. If you missed more than one session in three, the window is wrong, not you.

A 2020 review by Schumacher and colleagues suggests that a consistent time, especially in the morning, may help people keep exercising, though the authors acknowledge the evidence is limited. If finding the time at all is the problem, time for training looks at the diary itself.

A worked example

Take an executive who wakes at 6:00, has a first call at 9:00, leaves the office at 19:00 and goes to bed at 23:00. The morning window, after an hour to wake up, is two hours. The evening window, keeping two hours before bed, is also two hours. The calculator suggests the morning because it tends to survive the day: a late meeting cannot cancel a session that has already happened. If the evening is more reliable in your role, choose it, and finish hard efforts at least an hour before bed.

In the heat, avoid the hottest hours, drink regularly and build up gradually. If you sleep poorly, finish vigorous sessions at least an hour before bed, and see a doctor if insomnia persists.

To fix your training window with a coach who comes to you at that hour, you can set up your space in the Club.