There is a good argument for why you should eat an early dinner

But there is an equal, if not better argument, for enjoying your breakfast and eating an earlier dinner.

Eating by design

Humans are made to be active and to eat when it’s light and to rest and fast when it’s dark. As the sun goes down, our melatonin rises, typically peaking a couple of hours before bedtime.

“It’s a signal to our body to sleep and so whenever anyone is eating when melatonin is high, you tend to see a poorer metabolic reaction,” explains Sean Cain, a circadian rhythm expert from Monash University. “This is part of the reason there’s more metabolic disease in shift workers who are eating more at night and less in the day… We shouldn’t be eating when we have high levels of melatonin.”

Heilbronn adds that our bodies are better geared to metabolise food in the morning.

“If you eat a meal at 7am the pancreas secretes more insulin, cells are better able to take up glucose, you have a smaller glucose response versus eating that same exact meal at 7pm,” she explains. “So it completely makes sense that early is better than late.”

Though it makes sense, the evidence for eating earlier is not yet strong, Heilbronn stresses. Still, new research is promising.

A study, published in Science in May 2022 found that when mice ate in a 12-hour window that aligned with the start of their most active time of day, they improved their health and increased their lifespan up to 35 per cent.

One retrospective analysis of more than 3000 people, published in 2020, showed that weight and health outcomes were better among those who ate more food early in the day. And although human studies have found that cardiometabolic benefits of TRE are independent of weight loss, another new study found that shifting our eating window to earlier in the day can enhance weight-loss efforts.

Let your body decide

Professor Amanda Salis, a weight loss researcher at the University of Western Australia, says that it is still too early to say if eating in one particular routine is better than any other.

“But one thing is for sure: if eating with a particular timing helps a person to avoid excess energy intake (ie. kilojoules from foods and beverages) … then that is something that has proven health benefits.”

That means that if you skip breakfast and are then so ravenous that you end up smashing junk food, then any fasting benefits are lost. If, on the other hand, skipping dinner leads you to snack on chocolate or chips instead, then that may not be good for you either.

At any time of the day what we eat is important. Provided we pay attention to our diet, it’s up to us when and how we fast, Salis suggests.

“I hypothesise that the effect of not eating for extended periods of time is stronger than the effect of eating at particular times in the day.”

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Sean Cain echoes the sentiment that the fast itself is what is important, but explains that the same fasting windows may affect people differently.

Among early birds, for instance, melatonin typically starts to rise earlier in the evening and decline earlier in the morning. So people who naturally like to wake up early and go to bed early may be better off having breakfast and eating earlier, or skipping dinner altogether.

Night owls, who like to stay up later and rise later, may be better off skipping breakfast and eating dinner, as their melatonin is likely to peak later at night and decline later in the morning. Other people are somewhere in between, though we may all benefit from bringing dinner forward a little as our bodies are trying to wind down.

The good news, Cain says, is that night owls are unlikely to feel like eating early and morning people are less likely to feel like eating late, so we can guide our eating and fasting by aligning with our body’s cues.

“It really depends on people’s rhythms and partially their melatonin levels,” says Cain, who eats his dinner at 6pm and never eats past 8pm. “I don’t think there’s a one-size-fits-all answer for this.”

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