In the study, subjects who hit the exercise bike for six all-out one-minute sprints followed by four minutes of rest, for a 30-minute workout in total, experienced slightly lowered levels of the hunger hormone ghrelin, without suffering any diminishing quality in sleep, even when training as late as 9pm.
Then again, that’s a pretty weird workout: a long way from what you’d do in Barry’s Bootcamp, and probably a far cry from anything you’d fancy in the old post-work/commute/dinner haze. And type of workout is definitely a factor researchers should be controlling for, as anyone who’s done a really serious weights session late at night and then come down with a case of the late-night muscle twitches will happily tell you. As, indeed, will their infuriated partners.
So what does the rest of the body of research into exercise timing say? This is certainly far from the first study to try to work out an optimal time for training; it turns out that there are quite a few factors to consider. Hauling yourself out of bed first thing in the morning, for instance, might help you get leaner: after an overnight fast (and pre-breakfast), you’re technically more reliant on fat as a fuel source than carbs, meaning you might burn of it.
Then again, research published in 2014 found that, over a four-week period, trainees who exercised in a fasted state saw no difference in fat loss from a control group who worked out after feeding.
One factor might be just how hard it’s possible to work while fasted, and here again timing comes in as a factor. In another study, published in the Journal of Sports Science, researchers found that athletes were able to push harder in the evening, even if they tended to what the study called ‘morningness’ – a happy reminder that, when you’re bleary-eyed at 6am and everyone else at the gym looks fresh as a forget-me-not, they’re suffering too.
It’s also worth remembering that, while an evening workout might cut down on snacking, daytime workouts can have a similar effect, and – according to a 2017 study – might suppress hunger throughout the day: handy, since at night you can brush your teeth or just go to bed to curb your cravings, while during the day there’s little escaping the lure of the biscuit barrel.
So mornings might be best after all? Well, not necessarily. Like a creaking computer, your body takes a while to get up to optimal running speed – even an hour or so after you wake up, you’re unlikely to be at the ideal body temperature for training, while your joints and nervous system can take even longer to wake up – one reason that most world records in ‘power’-based sports like weightlifting or sprinting – tend to be set in the afternoon.
If you’re working out extra early, another consideration is sleep – it’s so vital to a whole host of bodily processes that you shouldn’t really be sacrificing it to get up early. The best option of all might be a lunchtime workout: but then you have to contend with other runners on the park path, tree-posers in the yoga class, or bench-and-curl bros taking up all the racks. Tricky.
The truth, as always, is that the best workout is the one you’ll do, not the one that’s optimal-but-impossible. If your office job’s so draining that you can barely make it to the station at 5:30, planning in a hot yoga class is doomed to failure – just like if you’re so prone to late-night streaming binges that 6am always sees you hammering the snooze alarm. Unless you’re an Olympic athlete or a professional boxer, you’re unlikely to need to worry about the sort of fractional differences in performance that come with time-specific training, and right now the evidence that it makes a difference to fat loss is negligible enough to ignore.
Train when you like, and if you really need evidence that timing doesn’t matter, please remember that The Rock trains at 4:30am, while his long-time nemesis Triple H hits the gym at 10pm every night. Sweet dreams.
Source: Joel Snape