Role of Chronotype in Dietary Intake, Meal Timing & Obesity

April 4, 2023

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Are you a morning person? Do you take an afternoon nap? Do you like to sleep in until the afternoon? All these are the different sleep preferences that differ among people. Did you ever think your sleeping pattern might affect your dietary intake? It's becoming increasingly obvious that what you eat matters just as much as what you consume. The timing of our meals affects our capacity to break down, digest, and metabolise food and our physical and mental functions.

Everyone has different sleeping habits, behaviours, and personality traits based on factors such as age, activity level, and sleeping environment. The individual circadian cycles that characterise people's degrees of alertness and activity throughout the day, known as "chronotypes," are used to categorise these activities.

Whatis circadian rhythm?

Due to Earth's rotation around its axis, almost all life on the planet employs an internal biological clock. Animals can really "know" the time of day because of natural daily cycles known as "circadian rhythms" (1). There is an endogenous time system in the suprachiasmatic nuclei (SCN) in the hypothalamus area of mammals' brains. The SCN of the brain's anterior hypothalamus receives signals of light and dark over a 24-hour period and serves as the "central clock" for this internal clock system (2).

What is chronotype?

Chronotype displays choices for when to carry out everyday tasks (3). A person's attitude defining personal preference for a circadian rhythm in behavioural and biological rhythm in relation to the external light-dark cycle is known as their "chronotype. Based on the variations in circadian behavioural phenotypes, chronotypes may be divided into three main categories: morning, evening, and intermediate chronotypes (4). Studies have shown that people with a morning chronotype tend to wake up early and enjoy activities earlier in the day. In contrast, people with an evening chronotype often wake up late and choose to perform activities later in the afternoon and evening. The intermediate chronotype is for people who follow the sun; they work well during office hours and also don't have any problem keeping a social nightlife. People with the evening type of chronotype are more likely to have greater rates of metabolic dysfunction, cardiovascular illness, and mental symptoms (5).

Importance of meal timing

The relationship between circadian cycles, metabolic functions, and nutritional intake is unbreakable. The timing of food intake may be altered as a temporal cue for the circadian system and is subject to various influences, such as an individual's chronotype (6). A study done on the association between chronotype and timing of energy and macronutrient intakes showed that the evening type had a generally lower intake of energy and macronutrients in the morning and a greater intake in the evening than the morning type, which was related to delayed energy and macronutrient intake timing (7).The synchronisation of our internal central and peripheral clocks with the external environment's light and darkness controls our circadian rhythms, thus helping us to sleep at night and even regulate our dietary intake during the day. Key metabolic functions also follow a circadian cycle to correspond with this behaviour, which explains why morning levels of glucose tolerance, insulin sensitivity, and food's thermic effects are higher than afternoon and evening levels (8).

Circadian rhythm and obesity

Adults have circadian patterns of eating, as well as comparable cycles of gut motility, the production of digestive juices, the absorption of meals that have been digested, and blood levels of lipids, amino acids, and carbs (9). Evidence shows that in evening chronotype people, those who have insufficient, disruptive, and late sleep are linked to a low intake of carbohydrates and a low dietary quality but a high fat intake (10).

A study done on the dietary intake of people with different chronotypes showed that, in comparison to other chronotypes, evening types are more frequently physically inactive and have worse subjective health (11). Evening chronotype is linked to higher BMI, binge eating patterns, and higher evening energy intake, especially from less fresh produce and more fast food and alcohol. Contrarily, the morning chronotype is inversely correlated with disinhibition and sensitivity to hunger and positively correlated with cognitive restraint. The chronotype affects the link between meal timing and BMI. This raises the possibility of an interaction between chronotype and meal time on hunger and eating behaviour (12).

Recent research has linked sleep deprivation and later bedtimes to an increased risk of obesity. Other weight-related behaviours may be influenced by circadian preference. People with evening chronotypes typically exercise less frequently, watch TV more, and consume fast food more frequently. The timing of meals and exercise also affects metabolism and the likelihood of gaining weight (13).

Conclusion

We attempt to comply with societal expectations by eating and sleeping at specific times. Still, in the end, we are all unique, and we need to identify our optimal state and make every effort to achieve it. Try eating before 9 p.m.; otherwise, it may affect your metabolism, according to the literature, so try eating early. You can schedule your meals to maintain a healthy metabolism and lower health risks by being conscious of your eating and sleeping patterns.

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