Maintaining a healthy weight and staying fit is no longer thought to depend solely on what you eat. Scientists are paying increasing attention to when you eat as well.
A mounting body of research indicates that consuming most daily calories earlier in the day may help speed up weight loss, reduce blood pressure and curb hunger for longer.
In a study published last year, researchers in Slovenia found that limiting eating to an 8am-to-4pm window led to an average ten-pound weight loss over three months. Participants also saw reductions in body fat and more stable blood sugar levels.
Sceptics argue, however, that the apparent gains may simply come from eating fewer calories within a more restricted period.
So, does meal timing offer benefits beyond calorie reduction alone?
Registered dietitian Sophie Medlin says there is good reason to think about when meals are eaten — and not only for people hoping to lose weight.
How efficiently the body processes food is linked to its wider daily rhythm, including when we wake, sleep and exercise, she explains.
Here, she sets out what the evidence says about the ideal times for breakfast, lunch and dinner, along with the least helpful time to snack for those trying to shed excess weight.
Eating breakfast, lunch and dinner earlier in the day is generally considered better for digestion and weight management
Is eating earlier really better?
“There’s no question that research suggests getting more of our daily energy intake earlier in the day may bring benefits for both weight and heart health,” Ms Medlin says.
Perhaps the most in-depth study is a 2024 meta-analysis which found that earlier calorie distribution and time-restricted eating produced reductions in weight – albeit relatively small.
‘Our bodies run on approximately 24-hour circadian rhythms,’ says Ms Medlin. ‘These influence how good our body is at converting blood sugar to energy and digesting food, as well as the level of our appetite hormones.’
In general, the body is more efficient at converting sugars in food into energy – and therefore calories burned – during the most active part of the day.
‘Eating earlier gives us more opportunity to use energy through movement,’ she adds.
One 2022 Harvard study asked 16 overweight and obese adults to stick to an early eating schedule for two weeks, and then pushed the meals back by four hours, but consuming the same calorie intake.
Early eaters ate one hour after waking – at around 8am, on average, – while the late eaters waited five hours, with some having their first meal as late as 12pm.
Those in the early group ate dinner at around 4.30pm, compared to 8.30pm in the late group.
Results showed that those on the later schedule had much higher blood levels of hormones associated with hunger, and lower levels of compounds released in response to fullness.
The researchers concluded that eating later could trigger changes in the gut that increase hunger signals, risking weight gain.
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However Ms Medlin caveats: ‘This study is interesting but it only involved 16 adults. More conclusive evidence is needed to prove the theory.’
She admits, though, that delaying most of our food until late evening could disrupt appetite regulation, and make blood sugars go awry.
What about skipping breakfast?
Intermittent fasting – which involves limiting calorie intake for a few days a week – remains popular among Britons.
The majority of fans follow a similar schedule; skipping breakfast and saving their calories for lunch and dinner, while cutting out the snacks.
A review on the diet plan published earlier this year suggested it could result in a body weight reduction of about 3 per cent (roughly five-and-a-half pounds in an average man).
However a wealth of other reviews have found that the benefits are likely just the result of eating fewer calories.
Scientists have found similar weight loss with other low-calorie diets. And some research suggests skipping breakfast could cause you to overeat.
One large observational study examining the dietary records of 23,488 American adults found that people who skipped both breakfast and lunch consumed, on average, about 187 more calories at dinner.
Another study involving almost 3000 older adults found delaying the first meal of the day by even an hour was associated with an 11 per cent higher risk of death.
‘Skipping breakfast risks a pattern whereby you eat very little throughout the day and then consume a large proportion of the day’s food late at night,’ says Ms Medlin.
‘This can encourage overeating, and large, rich meals close to bed may cause reflux, bloating or disturbed sleep.’
She adds that, as the body is less able to convert food to energy at night, excess calories are more likely to be stored as fat.
Is there an optimum time for every meal?
According to Ms Medlin, there aren’t any specific timings that guarantee that we won’t overeat, become sluggish, or lose focus.
However there are ‘useful windows’ to stick to which are based on the strongest scientific evidence.
‘Breakfast could be eaten within around one to two hours of waking up, lunch approximately four to five hours later, and dinner ideally two to three hours before bed,’ says Ms Medlin.
‘For someone following a conventional sleep pattern, that might mean breakfast between 7am and 9am, lunch between 12pm and 2pm, and dinner between 6pm and 8pm.’
But most crucial is ensuring the hours before bed are not the ‘main eating period of the day’, she adds.
‘Finishing a main meal approximately two to three hours before lying down is a sensible target. This provides time for digestion and can reduce reflux or discomfort.