What time do you eat your dinner? While it may seem sophisticated to opt for a chic 9pm meal like the Spanish and science says eating earlier may be better for our health.
Welcome to the world of chrononutrition — or eating in alignment with our circadian rhythm.
The circadian rhythm is our body’s internal 24-hour clock, which influences everything from when we feel sleepy, to hormone levels, digestion, and metabolism. This biological rhythm is governed by a master clock in the brain — the suprachiasmatic nucleus (SCN), a cluster of neurons in the hypothalamus that responds to light and dark signals from the environment.
But the circadian clock isn’t just in our brains — almost every organ and cell in our bodies has its own clock, too. They help regulate things like blood sugar control, fat storage, and gut function — processes that all function best if we stick to our natural state of being awake in the day and asleep in the night. As well as responding to daylight, these clocks rely on cues from meal timings to stay in sync too.
When these rhythms are disrupted — say, by eating a kebab at 1am or constantly changing meal times — it can throw us off balance and, in the long term, put us at higher risk of disease.
“If you're eating very late into the night, then that night your body clock gets confused and thinks: Huh? Was it a delayed dinner? Or was it an early breakfast?,” leading circadian rhythm researcher Dr Satchin Panda said in the ZOE podcast.
“And for the next few days, it stays confused. All the body clocks: the clocks in the liver, gut, heart, kidney, all of those clocks get disrupted and they can’t work so well.”
Research suggests that when we align our eating habits with our circadian rhythm it can aid our metabolic health, improve our sleep, and reduce our risk of chronic disease.
“We know that having a strong circadian clock is good for health,” he adds. “In modern life, it's very hard to control light exposure because late into the night, we're exposed to artificial light. What can we control? When we eat, and with that we change our health.”
What are the best ways to align your eating with your internal body clock? And does this mean the end of the late night dinner forever?
Front-load your calories
If you normally eat your biggest meal of the day in the evening, consider swapping it to breakfast or lunch.
A 2020 study in The Journal of Clinical Endocrinology & Metabolism found that people who ate a larger breakfast and smaller dinner burned more calories, had better insulin sensitivity, and reduced hunger throughout the day, than those who did the opposite.
Our circadian rhythm regulates hormone release and metabolic functions in anticipation of daytime activity. For example, insulin — which helps regulate blood sugar — works better in the morning, meaning we process carbohydrates more effectively. Studies also show higher diet-induced thermogenesis (calorie burn from eating) earlier in the day. It’s our bodies’ way of syncing fuel use with expected activity.
This is why it’s better to consume the bulk of our calories earlier in the day, not late at night, when your body is winding down.
Stick to regular meal times
Eating erratically can throw off the internal clocks in organs like the liver and pancreas, affecting glucose regulation and metabolic function.
Research led by Professor Frank Scheer at Harvard found that irregular eating disrupts circadian rhythms and increases the risk of obesity and diabetes. Keeping a consistent meal schedule reinforces the body’s natural rhythms, supporting everything from digestion to hormone balance. It doesn’t mean excessively rigid routines – just aiming for relatively stable eating times most days.
Set an ‘eating window’
Time-restricted eating (TRE) — eating within a defined daily window — appears to have benefits for health.
Dr Satchin Panda, a leading circadian biologist, has shown in both mice and human studies that TRE (particularly when eating is confined to an early 8-10 hour window) can lead to weight loss, better blood sugar levels, and even lower cholesterol — independent of calorie intake. It seems to work best when the window begins earlier in the day, in sync with natural light exposure.
A King's College London study involving over 37,000 participants found eating within a 10-hour window – for example from 9am to 7pm – improves mood, energy levels, and, even, reduces hunger. “What's really exciting is that the findings show that you don’t have to be very restrictive to see positive results. A ten-hour eating window was manageable for most people,” said one of the researchers, Dr Sarah Berry.
Skip late-night snacks for a healthy gut
Eating within a set window means fasting when you’re not in that window. In other words if your eating window finishes at 7pm you couldn’t have a cheeky glass of wine with a handful of crisps at 9pm.
The digestive system isn’t designed to be “on” all the time and having an extended break without food (say for 14-16 hours overnight) is thought to support a healthy gut microbiome. It gives a chance for the gut’s “cleaning crew” to come in — sweeping away undigested food particles and creating a healthier microbial environment. This rest from food also might cause certain beneficial bacteria to increase.
Eating too frequently — especially late at night — can interrupt this process, leading to bloating, bacterial overgrowth, and impaired digestion. In general try to stop eating 2-3 hours before bed.
When is the best time of day to work out?
It’s not just when we eat that helps strengthen our internal body clock — exercise can have an effect too, though it’s less clear-cut.
Morning workouts can support fat burning and reinforce your circadian rhythm, helping improve sleep and consistency.
But the afternoon (around 2-6pm) is when strength, endurance, and coordination peak, making it ideal for high-intensity or performance-focused training.
Evening exercise is still beneficial but may interfere with sleep if done too close to bedtime. Overall, aligning your workouts with when you feel you have the most energy (for most people late morning to mid-afternoon) – can optimise results and support better sleep and metabolic health. The most important factor, though, is choosing a time that works for you.
Don’t stress about perfection
While aligning your meals with your circadian rhythm can support long-term health, it’s important not to obsess.
As Professor Satchin Panda notes, occasional late meals or snacks won’t derail your metabolism. What matters most is your overall pattern — consistency over weeks and months, not single days.
Food isn’t just fuel, it’s also social and emotional, and flexibility is key to a healthy diet and general wellbeing. So enjoy that celebratory dinner or late-night kebab every now and then. Just aim to return to your natural rhythm most of the time and your body will thank you.
