Is Meal Timing Important?
By: Lian Delgado, dietetic-student volunteer, UBC School of Kinesiology, revised, edited and reviewed by Kinga Balogh, Registered Dietitian, and the JM Nutrition Team
Is meal timing important in overall health?
In this post, our team of registered dietitians explores the importance of meal timing in some depth.
The Importance of Meal Timing: Introduction
Have you ever craved a midnight snack and satisfied those cravings by grabbing a bag of chips and finishing it up before you know it?
Did you ever skip breakfast?
Can you recall a time when you felt hungry, yet got distracted and then the sensation completely disappeared?
Most of us can relate to similar situations. That’s a given.
Emerging research suggests that meal timing influences one’s circadian rhythm, metabolic capacity, physiological function, and body weight (Kessler & Pivovarova-Ramich, 2019). These considerations certainly create a strong argument for to optimize meal timing to promote optimal health.
In order to demonstrate the importance of meal timing, we first must examine an integral concept: circadian rhythms.
The Importance of Meal Timing: Background Information
What is circadian rhythm?
Before we discuss the importance of meal timing and explore associated strategies we need to familiarize ourselves with the circadian rhythm.
The term, circadian rhythm, is defined as “the physical, mental, and behavioural changes an organism experiences over a 24-hour cycle” (NIGMS, 2023).
More commonly, the circadian rhythm can be referred to as the body’s biological clock. It is known to be largely affected by light and darkness. That said, it is also influenced by other factors. These include nutrition, stress levels, exercise, jet lag with travel and shift work, among the most commonly quoted factors (Cleveland Clinic, 2024).
Moreover, circadian rhythm is crucial to the functioning of various physiological and psychological aspects of the human body (Franzago et al., 2023).
The science behind circadian rhythms
Our circadian rhythm is controlled by the suprachiasmatic nuclei (SCN) located in the hypothalamus, which is in the brain (Franzago et al., 2023). The SCN houses many single cell circadian oscillators working in harmony to produce coordinated circadian signals that control the body (Froy, 2007).
Aside from the SCN as the main regulator of the circadian rhythm, there are peripheral clocks in various organs of the body. These are are located in the heart, liver, pancreas, skeletal muscle and adipose tissue (Rogers et al., 2021). These peripheral clocks are not only influenced by the SCN, but also the external environment, particularly from nutrition, temperature, physical activity, and more (Serin & Tek, 2019).
Both the SCN and the peripheral pathways synchronize together to maintain the body’s circadian rhythm (Peters et al., 2024). The internal clocks in principle influence key bodily dynamics, such as the sleep-wake cycles, feeding and fasting cycles, and promote good physiological functioning (Boege et al., 2021).
Effect of circadian rhythm on hormone regulation
Alignment in circadian rhythm allows the body to preserve efficient metabolism and maintain energy balance (Serin & Tek, 2019). Circadian rhythms are capable of achieving this as the SCN coordinates with various hormones. These include melatonin, growth hormones, cortisol, insulin, glucagon, leptin, ghrelin, and GLP-1 (Panda, 2016).
Melatonin is possibly the most heard of hormone that is produced by our circadian system. With decreased light exposure in the latter part of the day, melatonin levels increase to facilitate the ease of falling and staying asleep overnight. During the day, when the photosensitive receptors of our circadian system get lots of light exposure, less melatonin is produced.
As a result, unless sleep deprived, most folks would report feeling awake, alert and more focused than at night. All of these hormones function in various metabolic pathways and ensure homeostasis in the body (Franzago et al. 2023).
1. Cortisol
For instance, exposure to light prevents melatonin release. This, in turn, encourages the secretion of cortisol. This hormone then stimulates arousal and promotes energy metabolism in adipose tissue and skeletal muscle (Panda, 2016). Cortisol is important in the modulation of glycogenolysis (glycogen breakdown), lipolysis (fat breakdown), and proteolysis (protein breakdown) (Serin & Tek, 2019).
Related: Cortisol Lowering Foods
How often cortisol is released and its serum levels are controlled by the circadian rhythm, and it is meant to peak before waking up then slowly decrease throughout the day in preparation for sleep at night (Serin & Tek, 2019).
Shift workers are at particular risk. Reason being, their circadian rhythms can easily be disrupted with light exposure during the night.
2. Insulin
The presence of light and food consumption prompts the coordination between the SCN and peripheral tissues wherein the secretion of insulin from the pancreas occurs (Panda, 2016). After you eat, insulin functions in glucose metabolism by allowing cells to uptake glucose for energy (Serin & Tek, 2019). This highlights the role of the circadian rhythm in glucose metabolism, as well as insulin signalling and secretion (Boege et al., 2021).
3. Glucagon
Glucose metabolism is also affected by the circadian rhythm during periods of fasting through its ability to interact with glucagon (Panda, 2016). When the body is in the fasted state, glucose needs to be released from stored sources to maintain stable blood sugar levels.
Glucagon is a critical hormone that maintains steady glucose levels in the human body. This hormone triggers the activation of protein kinase A (PKA). This then enables glycogenolysis (glycogen breakdown) and gluconeogenesis (formation of non-carbohydrate substrates into glucose) to occur (Panda, 2016).
In summary, the circadian rhythm plays a pivotal role to help ensure optimal glucose metabolism in your body (Peters et al., 2024).
4. Leptin and ghrelin
Leptin and ghrelin are hormones that are responsible for hunger and satiety or the sensation of fullness following meal consumption.
Both of these hormones function separately and coordinate with each other to control appetite and satiety (Jones, 2023).
After a period of fasting, such as when you don’t eat overnight, ghrelin is secreted in the morning to create the sensation of hunger and to encourage food seeking behaviours (Jones, 2023).
During the fed state, our adipose tissues produce leptin. This prompts our brain to acknowledge that we have met our energy needs, leaving us satiated and disinterested to continue eating (Jones, 2023).
The balance of these two hormones in the body are dependent on our circadian rhythm. Hence, an alignment on our circadian rhythm ensures that leptin and ghrelin levels are adjusted at appropriate times to avoid over- and under-eating (Serin & Tek, 2019).
Related: Hormonal balancing with a dietitian
The Importance of Meal timing: Risks of Poor Meal Timing
Meal timing is no doubt important. As such, there are risks involved when meal timing is suboptimal.
While most people notice occasional delays in getting to their meals or end up skipping meals from time to time, chronic irregular eating habits and inconsistent meal times can become a hindrance, when it comes to overall health and energy levels.
Studies show that consistently skipping meals, irregular meal times, eating late at night, and emotional eating will offset the circadian rhythm. This will then will impact metabolism and may cause positive energy balance or surplus food intake (Franzago et al., 2023).
Related: Dietitian for emotional eating support
Poor meal timing has been observed to cause impairments in glucose and lipid metabolism (Kessler & Pivovarova-Ramich, 2019).
Furthermore, correlations have been made regarding circadian system dysregulation and disease onset, such as type 2 diabetes, cardiovascular disease, weight gain and other metabolic disorders (Peters et al., 2024).
Related: Metabolism 101
Following such unhealthy eating habits in the long run may undermine the body’s optimal functioning, leading to increased body weight, higher body fat content, diminished glucose tolerance, greater insulin resistance, increased blood pressure, and higher cholesterol (Peters et al., 2024).
Related: Dietitian for weight loss
Impact of Meal Timing on Digestion and Metabolism
Food is known as a powerful component in influencing peripheral clocks. It is, therefore, important to consume food at appropriate times to prevent an imbalance in the circadian rhythm (Froy, 2007).
Research shows that consumption of food is crucial to the peripheral clocks of the liver, heart, and pancreas (Peters et al., 2024).
As meal times are normally synchronized with the light-dark cycle, it has been proven that the timing of meals strongly impacts peripheral clocks (Peters et al., 2024).
For example, consistent intake of food outside of the typical daytime window of eating, such as overnight, resulted in disrupted coordination between the SCN and the peripheral clocks. This is due to the release of hormones partaking in metabolic homeostasis, appetite and satiety (Peters et al., 2024).
According to Paoli et al. (2019), individuals who consume breakfast are less likely to experience weight gain than people who skip breakfast. Skipping breakfast has been associated with higher caloric intake and more frequent meals throughout the day. This is typically referred to as the body’s attempt to make up for missed nutrients (Peters et al., 2024). This attempt usually leads to overconsumption.
Additionally, greater fat breakdown and higher insulin levels were noted whenever individuals skipped breakfast (Paoli et al., 2019). This phenomena could potentially lead to mild inflammation and disrupted glucose regulation (Paoli et al., 2019). Both are rather unfavourable conditions.
A higher caloric intake in the morning, such as during breakfast, and lower intake later in the evening, was suggested to be beneficial from a metabolic point of view. Hypothetically, this is due to optimized glucose homeostasis (Peters et al., 2024).
If you consume breakfast earlier in the day and have dinner at an earlier time, you effectively reduce the risk of cardiovascular disease, in comparison with those that skip breakfast and have later dinners (Paoli et al., 2019).
While the above are theoretically beneficial considerations, individualized meal planning is required to determine optimal meal times for most individuals with the help of a registered dietitian and nutritionist.
Kessler and Pivovarova-Ramich (2019) emphasized the importance of timing one’s meals as it is a potential contributor to obesity and chronic disease. Their findings indicate that heavier meals during breakfast allowed for greater weight loss while also decreasing glucose, insulin, and ghrelin concentrations when compared to people who consumed the same amount of calories during dinner (Kessler & Pivovarova-Ramich, 2019).
This is due to the correlation between food consumption at night and extreme glucose fluctuations, and associated increase in insulin levels (Rogers et al., 2021).
Additionally, people who had the greatest amount of food intake during lunch or dinner time showed to have greater probability of high BMI (Paoli et al., 2019).
Overall, delayed meal timing has been linked to increased daily caloric intakes and higher BMI (Boege et al., 2021). While these associations are insightful, folks are encouraged to plan meal times that work best for their work schedules, activity patterns and health goals with the help of a professional such as our Winnipeg dietitian.
Factors That Influence Meal Timing
There are a diverse set of factors that should be taken into account when observing the timing of meals in various individuals. These factors have been observed to impact the circadian rhythm of the body. The three main factors that influence meal timing are (Peters et al., 2024):
1. Physiological factors: genetics, age, sex, body composition, as well as physical and mental conditions
2. Behavioural and personal preferences: physical activity levels, chronotype, dietary habits, lifestyle choices, and artificial light exposure
3. Cultural and environmental factors: religious beliefs, tradition, economic status, occupational demands, and social responsibilities
A nutrition professional such as our Montreal dietitian, Nadja, can help honour and factor in the above mentioned physiological, behavioural, cultural and environmental factors as clients set out to optimize the composition and timing of their meals.
Manipulating macronutrient intake throughout the day
After understanding the importance of meal timing, it would be beneficial to our health if we tailored our meal composition to our circadian rhythm. Appropriate meal timing and macronutrient balance has shown to alleviate symptoms related to metabolic conditions by improving insulin sensitivity and boosting glucose tolerance (Franzago et al., 2023).
Have a higher calorie intake earlier in the day, particularly at breakfast (Paoli et al., 2019). It is more favourable to consume heavier meals from the morning to early afternoon over a high calorie meal for dinner later in the evening (Franzago et al., 2023). These high calorie meals should be rich in both protein and carbohydrates (Jakubowicz et al., 2013).
A meal that is high in protein provides greater satiety through producing lower levels of the hunger signaling hormone called ghrelin, while the consumption of carbohydrates reduces the risk of metabolic syndrome (Lopez-Minguez et al., 2019). High protein intake earlier in the day does not only promote satiety, but it also supports recovery post-exercise or strenuous activities of daily living and stabilizes hormones related to appetite (Paoli et al., 2019). A fact that is supported by JM Nutrition sports dietitians.
In addition, greater consumption of carbohydrates earlier in the day supports glucose homeostasis and provides sufficient energy throughout the day (Franzago et al., 2023).
Larger meals during later in the evening (i.e. dinner) are not recommended. Therefore, consume a macronutrient balanced and more modest meal in the latter part of the day (Jakubowicz et al., 2013). Include protein, healthy fats and carbohydrates with low glycemic index for dinner. Doing so will help to ensure proper regulation of glucose metabolism, promote better sleep quality and allow metabolic homeostasis throughout the night (Rogers et al., 2021).
You should also aim to avoid the consumption of foods late at night to avoid any interference with their circadian rhythm.
In addition, foods that are high in fat or sugar content can interfere with the body’s fasting state, by negatively affecting melatonin production, thereby disrupting sleep (Boege et al., 2021). While the occasional late night meal or snack is by no means detrimental, aim for more simplicity through wholesome meals in the evening hours. This can serve your health well.
The Importance of Meal Timing: Other Considerations
We have shown how meal timing is crucial to our overall health. However, it is also essential to factor in individual characteristics. Therefore, an individualized approach to meal planning is recommended, when possible. Here are some guidelines to ponder upon further:
1. You know your body best. Observe how your body reacts and how you feel when you consume meals with various macronutrients profiles and nutrient density. Observe your mental focus, energy levels, digestive health and stress tolerance as ways to assess the impact of food on your overall wellness.
2. Align meal times with your circadian rhythm. This means food intake should occur in the daytime, wherein our bodies are more metabolically active.
3. Avoid snacks or dinner late at night. Limit food consumption by around 2 to 3 hours prior to sleep.
4. Ensure consistency in patterns of meal timing. Have your meals at roughly the same time and limit skipping meals, whenever possible.
5. Consider your physical activity levels. Have a meal rich in complex carbohydrates with a protein source 2 to 3 hours prior to exercise, and possibly an easily digestible carbohydrate 30 minutes before exercise.
After you exercise, consume a protein rich meal with approximately 15 to 30 grams of protein to aid in muscle protein synthesis and recovery.
6. Think about your goals and needs. This is where an individualized approach is crucial as meal timing and composition is dependent on your health goals, bodily needs, and if applicable, medical conditions.
7. Seek professional help! The importance of meal timing cannot be overlooked. A registered dietitian such as our Vancouver dietitian, Shirley, will guide and help you figure out when to eat your meals, what foods will help, and more.
Why is Meal Timing Important? Conclusion
Overall, meal timing plays a significant role to help promote circadian rhythm synchronization, optimal metabolism and reduction of chronic disease.
When you have larger meals earlier in the day and adjust macronutrient intake based on our body’s physiological needs, as well as the avoid eating late at night and skipping meals is recommended for overall health and well-being.
While meal timing and composition is a fundamental consideration in meal planning, managing stress, fostering supportive relationships, aiming for optimal sleep routines and maintaining an active lifestyle constitute additional components of optimal self-care from a holistic perspective.
If you have a question as to why meal timing is important or similar, get in touch with us. If you’re interested in personalized nutrition counselling by one of our dietitians and nutritionists for a related or non-related matter, book a free consultation and we will gladly lend a hand.
References and Resources
Boege, H.L., Bhatti, M.Z., St. Onge, M. (2021). Circadian rhythms and meal timing: Impact on energy balance and body weight. Current Opinion in Biotechnology, 70, 1-6. https://doi.org/10.1016/j.copbio.2020.08.009
Cleveland Clinic (2024). Circadian Rhythm. https://my.clevelandclinic.org/health/articles/circadian-rhythm
Franzago, M., Alessandrelli, E., Notarangelo, S., Stuppia, L., & Vitacolonna, E. (2023). Chrono-nutrition: Circadian rhythm and personalized nutrition. International Journal of Molecular Sciences, 24(3), 1-17. https://doi.org/10.3390/ijms24032571
Froy, O. (2007). The relationship between nutrition and circadian rhythms in mammals. Frontiers in Neuroendocrinology, 28(2-3), 61-71. https://doi.org/10.1016/j.yfrne.2007.03.001
Jakubowicz, D., Barnea, M., Wainstein, J., & Froy, O. (2013). High caloric intake at breakfast vs dinner differentially influences weight loss of overweight and obese women. Obesity, 21(12), 2504-2512. https://doi.org/10.1002/oby.20460
Jones, B. (2023). Want to lower appetite? Get to know ghrelin and leptin. Verywell Health. https://www.verywellhealth.com/ghrelin-and-leptin-7970365
Kessler, K. & Pivovarova-Ramich, O. (2019). Meal timing, aging, and metabolic health. International Journal of Molecular Sciences, 20(8), 1-16. https://doi.org/10.3390/ijms20081911
Lopez-Minguez, J., Gomez-Abellan, P., & Garaulet, M. (2019). Timing of breakfast, lunch, and dinner. Effects on obesity and metabolic risk. Nutrients, 11(11), 1-15. https://doi.org/10.3390/nu11112624
National Institute of General Medical Sciences – NIGMS (2023). Circadian Rhythms. https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx
Panda, S. (2016). Circadian physiology of metabolism. Science, 354(6315), 1008-1015. https://doi.org/10.1126/science.aah4967
Paoli, A., Tinsley, G., Bianco, A., & Moro, T. (2019). The influence of meal frequency and timing on health in humans: The role of fasting. Nutrients, 11(4), 1-19. https://doi.org/10.3390/nu11040719
Peters, B., Vahlhaus, J., & Ramich-Pivarova, O. (2024). Meal timing and its role in obesity and associated diseases. Frontiers in Endocrinology, 15, 1-14. https://doi.org/10.3389/fendo.2024.1359772
Rogers, M., Coates, A.M., & Banks, S. (2021). Meal timing, sleep, and cardiometabolic outcomes. Current Opinion in Endocrine and Metabolic Research, 18, 128-132. https://doi.org/10.1016/j.coemr.2021.03.006
Serin, Y. & Tek, N. (2019). Effect of circadian rhythm on metabolic processes and the regulation of energy balance, Annals of Nutrition and Metabolism, 74(4), 322-330. https://doi.org/10.1159/000500071
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Kinga Balogh is a registered dietitian for eating disorders and disordered eating support.
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