Scientists have worked out exactly what you should be doing – and when – for effective weight loss. Here’s our round-the-clock guide. 

If you’re really serious about shifting kilos, you’ll be working out while the rest of the world is pouring their first cup of coffee. That’s according to a new study of more than 5,000 people from Franklin Pierce University in New Hampshire, USA, which has revealed that the best time of the day to exercise is between the hours of 7am and 9am.

Researchers found that people who did 150 minutes of pre-work training a week were almost three kilograms lighter and had a lower BMI than those who got their sweat on later in the day. They were also less likely to have unhealthy diets and consumed fewer calories than those who moved their bodies mid-morning or later.

What that means in reality? “Our findings propose that the daily pattern of moderate to vigorous physical activity could be another important dimension to describe the complexity of human movement,” says study author, Dr Tongyu Ma. But is it possible to continue this cal-burning fest throughout the entire day? In a word: yes. So here’s our guide to maximising your body clock.

7am: Time to wake up

While it’s true that some people are natural night owls, the 21st-century rat-race is geared to early risers. 

“The idea now is that every organ, and possibly every cell, has its own clock, and these are synchronised by a clock in the brain, which itself is set by photo-receptors in the eye that respond to light,” explains Professor David Whitmore from University College London, who specialises in chronobiology (a field of biology that examines timing processes).

Ideally, you’ll be consistent with your wake-up times. “If you keep a regular sleep-wake cycle, regular meal times and regular light-exposure times, that keeps the whole body clock on time, which in turn keeps everything else on time,” adds Dr Guy Meadows, sleep expert and founder of The Sleep School.

7.20am: Get your running shoes on

It makes a major difference to overall health and wellbeing. According to Ma, cardiovascular exercise is likely to be key for those who work out in the mornings. “Exercise can burn fat and glucose,” he says. “After an overnight fast, the glucose stored in our body is low. Therefore, when we exercise our muscles are likely to burn more fat. 

I would recommend 40 minutes of aerobic exercise before breakfast, such as running or biking.” So lace up those trainers and get ready to reap the metabolism-boosting rewards.

10am: Eat breakfast 

Intermittent fasting is one of the hottest topics in health for a reason, with numerous studies backing up its benefits. For weight loss, scientists from King’s College London recommend eating within a 10-hour window. Put simply, 10am offers the chance to fast slightly later in the morning, so you can finish eating before 8pm and give your body time to digest before bed. 

A study from the University of Surrey found that pushing your eating time one and a half hours later results in you eating fewer kilojoules.

“There’s evidence to show that eating in line with your body clock will improve your metabolic health, inflammation and weight,” says leading nutritional scientist, Dr Sarah Berry. 

Focus on starting your day with protein, like eggs or salmon. Studies from Japan have found that people are better at metabolising and building muscle from protein when it’s consumed in the morning, compared to when it’s piled onto your plate later in the day.

12pm: Finish your last cup of coffee 

While one unit of alcohol takes an hour for the body to break down, it takes up to six hours for it to clear the caffeine from a single shot of espresso from your system. Yes, you read that right. “At minimum, you need to leave at least a six-hour break between drinking coffee and going to sleep,” advises Meadows. “Drink two or three cups a day if you like, but ideally stop at noon.”

This is important because a lack of good-quality sleep can actually lead to overeating. “When we’re sleep-deprived, our bodies raise levels of ghrelin and lower levels of leptin, meaning we’re hungrier and find it harder to feel satiated,” says hormone expert, Emma Bardwell. These gut hormones are vital in regulating appetite – ghrelin tells the brain that you’re hungry, while leptin tells you that you’re full and can stop eating.

2pm: dig into some carbs for lunch

This is the meal where you should get most of your carbs, says Ulrike Kuehl, head of nutrition at the metabolism-tracking app, Lumen. “Consuming carbs for lunch will be important to give you some fuel to get you through the rest of the day,” she says. 

“It makes sense for most people if you look at the average metabolic flexibility to have more carbs in the middle of the day – that’s when people tend to be more sensitive to insulin 

and so better at processing them.” 

All this is even more important to give you energy to exercise after work. So fill up on carb heroes like grainy bread, sweet potato and brown rice to power through your PM tasks. 

3.45pm: Give yourself a short break to just daydream or do nothing

“One of the big problems these days is that the only time we take to pause is when we go to bed,” says Meadows. “That’s when your mind races because your ‘default mode network’, the part of your brain responsible for mental chatter, hasn’t had the chance to catch up on the day. Factoring in simple breaks to just do nothing is essential to sleeping better later.”

The proof? In 2015, a group of scientists from around the world published guidelines in The British Medical Journal, advising that we should get up from our desks every hour and walk for two minutes. Doing so cuts the risk of premature death by 33 per cent, by burning calories and keeping the body active.

5pm: Grab some weights (or yoga pants)

Crazy but true: between 4pm and 6pm, your core body temperature is at its highest and your muscles and joints are most warmed up, something that was confirmed by a 2019 study from the Scripps Research Institute in California. As a result, now is the time you’ll get the most out of strength and movement exercises. Moves like yoga or weight training are genius for building muscle which, in turn, is vital for burning fat. The reason? Muscle tissue requires more calories to maintain than fat tissue. 

“The more muscle you have, the more calories you’ll burn,” says personal trainer, Sarah Lindsay. “Cardio and general activity are great for you in all sorts of ways, but they need to be combined with getting stronger.”

A 2018 review of 23 different studies about exercise timings found that people who exercised in the evening fell asleep faster and spent more time in deep rest. One word of caution: be wary of exercising too close to your bedtime or too intensely late at night; the review found that intense exercise in the hours before bed delayed sleep onset by an hour.

6pm: Finish dinner

Usually wolf down a huge meal just before hitting the sheets? Then know this: “The most effective thing people can do for weight loss is to eat a couple of hours earlier in the evening than they might think – I’d say three or four hours before bed,” says Kuehl. 

“If you eat late at night it increases blood glucose and insulin, which negatively impacts sleep. The cells of your metabolism need time to rest and regenerate, so if those cells are active your body has trained itself not to shut down until they do. If you don’t sleep well, you’re more likely to gain weight.” Makes sense, and duly noted.

8pm: Skip the wine while you’re watching TV

Sure, it might be tempting to crash on the sofa with a glass of vino, but it’s generally unwise. “The body detects alcohol and sees it as a toxin, so it focuses all its resources on detoxifying that alcohol,” explains sports scientist, Nigel Stockill. All the processes by which the body would normally start to get you ready to sleep, such as slowing down the heart rhythm, get neglected until the body has detoxified the booze. 

“As little as one unit of alcohol in your system at bedtime can delay the onset of restorative sleep by about an hour. Have two large glasses of wine late in the evening and sleep for six hours, and you may not get any restorative sleep – and therefore won’t recover overnight. And you’ll also crave carbs the next day.”

10pm: Get to bed

Ideally you’ll have been slowing down, closing your curtains and switching off your smartphone before this point, but aim to get about eight hours of sleep to help shift the stubborn kilos. A 2022 study from the University of Chicago Medical Centre found that going to bed 75 minutes earlier than you normally would helps you consume 270 fewer calories (the equivalent of three biscuits).

Want more proof? Another study found that levels of a chemical called 2-arachidonoylglycerol (2-AG), which increases the amount of pleasure we derive from eating, rose by a third when volunteers were sleep-deprived. In short: you’ll want to eat more. So do yourself a favour and turn in early.