Many people believe that there is a greater impact of what are we eating on health instead of when we are eating. However, the food we eat is digested differently at different times.
So why is there a difference in the digestion of food at different times?
It is because of the circadian rhythm that moderates our pattern of sleeping and waking up over 24 hours (1). Mental, physical, and behavioral processes are influenced by circadian rhythms including eating and food digestion (2).
Vice versa, circadian rhythm is also influenced by mealtime. An association has been found between the circadian rhythm and mealtime along with weight status and insulin resistance causing conditions like diabetes and obesity (3–6).
What is the best time to eat?
A healthy weight, improved energy, and decreased risk factors of metabolic conditions are linked with consistent mealtimes (7,8).
- Breakfast: Considered as the most essential meal of the day as it sets the pattern for the level of sugar in the blood for the whole day. It is believed that breakfast should be taken in immediate few hours after waking between 6 and 10 a.m. Scientific evidence also suggests that diet quality may get affected if breakfast is skipped because more calories are eaten during lunchtime when breakfast is skipped (9–12). Moreover, those trying to lose some kilos can take benefit from eating more calories in breakfast than in lunch (13,14).
- Lunch: Lunch should be eaten at that time when the metabolism is at its highest which is between 10 a.m. and 2 p.m. This provides a stronger digestive function to the food. The meals taken at lunchtime should be lighter than what is consumed at breakfast and dinner (15).
- Dinner: Better health outcomes result from eating an early dinner in the evening having fewer calories. The circadian rhythm is regulated by the release of the hormone melatonin which is released at night and regulates the sleep-wake cycles (9,16). With melatonin release, the secretion of insulin reduces therefore the digestion of sugars like glucose is inhibited. Thus, when dinner is scheduled too close to bedtime becomes a risk for chronic illnesses (9,17,18).
What should be eaten to maintain a healthy weight?
A healthy weight can be maintained with an eating plan that contains a variety of food. There is a direct impact of the number of calories we eat and drink on the weight because the same number of calories should be consumed that can be burned by the body to maintain a healthy weight (19).
The diet should contain all the ingredients from the food pyramid. The food we eat should carbohydrates, fats, proteins, minerals, and vitamins. Fruits, vegetables, pulses, dairy products, and grains all should be part of the diet. Dark and green leafy vegetables, tomatoes, oranges, and fresh herbs are a source of minerals, fibers, and vitamins, and just adding onions, broccoli, and peppers in omelets and stews not only enhance the color of food but also provide the required nutrients (20).
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2. National Institute of General Medical Sciences. Circadian Rhythms [Internet]. [cited 2022 Mar 17]. Available from: https://www.nigms.nih.gov:443/education/fact-sheets/Pages/circadian-rhythms.aspx
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15. Dashti HS, Gómez-Abellán P, Qian J, Esteban A, Morales E, Scheer FAJL, et al. Late eating is associated with cardiometabolic risk traits, obesogenic behaviors, and impaired weight loss. Am J Clin Nutr. 2020 Oct 6;nqaa264.
16. McHill AW, Phillips AJ, Czeisler CA, Keating L, Yee K, Barger LK, et al. Later circadian timing of food intake is associated with increased body fat. Am J Clin Nutr. 2017 Nov;106(5):1213–9.
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18. Sutton EF, Beyl R, Early KS, Cefalu WT, Ravussin E, Peterson CM. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metab. 2018 Jun 5;27(6):1212-1221.e3.
19. Harvard School of Public Health. Food and Diet [Internet]. Obesity Prevention Source. 2012 [cited 2022 Mar 17]. Available from: https://www.hsph.harvard.edu/obesity-prevention-source/obesity-causes/diet-and-weight/
20. CDC. Healthy Eating for a Healthy Weight [Internet]. Centers for Disease Control and Prevention. 2022 [cited 2022 Mar 17]. Available from: https://www.cdc.gov/healthyweight/healthy_eating/index.html