Meal Timing and Health: Are We Eating at the Wrong Times? What Is the Ideal Eating Schedule?
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It is not only what you eat but also when you eat that is crucial.
“Eat breakfast like a king, lunch like a prince, and dinner like a pauper,” my Spanish friend Javier Hierzfeld shared, recalling how he understood this wisdom from a young age.
In Spain, lunch is the largest meal of the day, while dinner is very light. “Some people even skip dinner and only have fruit and yogurt,” he added.
In the UK and the US where lighter meals are common at midday and larger dinners are typical, scientific studies on ‘chrononutrition’ reveal that we may be following a reversed eating pattern.
Healthy eating is not just about what to eat, but also when to eat, which carries equal importance.
Numerous studies have found that from weight loss to preventing cardiovascular diseases, our body’s ‘biological clock’ or ‘circadian rhythm’ plays a significant role in how food is metabolized and our overall health.
Let’s explore why this is and how we can adjust meal timing to benefit from it.
Set Meal Times According to Your Body’s Internal Clock
Marta Garaulet from the University of Murcia in Spain began investigating how meal timing affects weight loss after observations at a weight loss clinic nearly a decade ago. She compared two patients on identical diets but with different mealtime patterns, resulting in varying weight loss outcomes.
One patient ate lunch at around 1 p.m., while the other, delayed by classes, ate later.
“That was the only difference,” Garaulet explained.
After six weeks, those who ate earlier lost more weight.
Following this, she further tested the impact of meal timing.
Together with colleagues at Murcia University, she observed 420 adults over a 20-week weight loss program in Spain. The study showed that early eaters lost weight faster than late eaters.
In another smaller trial, 32 healthy women consuming the same meals over two weeks showed that those eating lunch later exhibited poorer blood sugar control and carbohydrate digestion. Multiple studies confirm that our biological clock, or circadian rhythm, strongly influences hunger, digestion, and metabolism.
But why does eating the same meal at different times have such a significant effect?
When I asked neuroscientist Frank Scheer from Boston, he said, “Biologically, we are not the same in morning and evening.” The body’s internal clock mostly governs various functions. Eating at times meant for rest can disrupt this balance, a phenomenon called ‘circadian misalignment.’
For example, the body regulates blood sugar differently depending on the time of day. A 2022 study of over 800 adults showed each participant consumed glucose-rich drinks containing about as many carbohydrates as a typical evening meal.
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When drinks are consumed four hours before sleeping, the body processes sugar effectively. However, drinking them at bedtime raises blood sugar levels and reduces insulin production.
Insulin is a hormone that helps regulate blood sugar.
Melatonin plays a significant role according to research. Its levels rise in preparation for sleep.
“When melatonin levels increase in the evening, eating then affects glucose control,” explained researcher Scheer.
Late meals have long-term risk implications for diabetes. Globally, the number of people with type 2 diabetes continues to rise.
Eat Earlier to Reduce Hunger
Having dinner late not only worsens blood sugar control but can increase hunger the next day by affecting hormones that signal fullness and hunger. Late eaters produce less leptin, a hormone that signals satiety to the brain.
Meal timing also influences fat storage processes. Eating late can cause fat accumulation in cells, making it harder to maintain a healthy weight.
An international study of 1,200 adults linked late eating with a higher risk of obesity and an increased body mass index (BMI). Eating earlier reduces this risk.
Eat More in the Morning for Heart Health
Eating early benefits heart health as well. A French study with over 1,000 participants found those who delayed their first meal in the morning had a higher risk of cardiovascular disease.
Night shift workers are advised to eat less during the day, but this is not universally required since dietary intake must meet energy needs.
If hungry, small protein-rich snacks are recommended.
Be Mindful When Eating
Our eating habits are often uncontrolled and influenced by our ‘chronotype,’ which determines if we wake early or sleep late, affecting meal timing.
Early risers tend to have quicker insulin responses and less melatonin production, while late eaters have weaker glucose control and higher risks of weight gain.
Sleep quality also affects appetite; poor sleep leads to greater food intake and weight gain.
How to Eat Smart
Experts recommend eating at regular times and consuming fiber-rich carbohydrates — such as whole grains, legumes, nuts, and fruit — early in the day. In the evening, meals should be light but rich in protein.
A recent study showed benefits of including sleep-promoting foods like almonds, nuts, seeds, and tryptophan-rich proteins such as chicken, salmon, and tuna at dinner.
Now I too want to pay closer attention to my body’s internal biological clock. I appreciate the Spanish tradition of a larger midday meal and plan to start cooking early for work.
While there is no fixed ideal time for dinner, it is best to eat more earlier in the day and have dinner at least three hours before bedtime.