The circadian diet: how to restore healthy sleep and lose weight

Now, when we spend a lot of time at the screens of phones and laptops, and we also do not have a normal daily routine, many find that they do not sleep as well as they would like. Hence, irritability, increased fatigue and uncontrolled cravings for junk food. Together with experts, we will tell you how to lose weight, normalize biological clock and improve health with the help of a circadian diet.

Circadian rhythms (biological clock)

All living things on Earth – from plants to mammals – obey daily rhythms. These biological rhythms play the role of a conductor of other processes that occur with special frequency at regular intervals. The most important biorhythm is daily, it is also called circadian.

In other words, nature has endowed us with an internal biological clock, which is directly related to the cyclical change of natural phenomena of day and night, therefore it is so important to observe the ratio of wakefulness and sleep to improve the quality of life and the functioning of the body as a whole.

The circadian rhythm (biological clock) is the basis of a person’s regular routine. This is why it is so important to maintain a consistent daily routine: go to bed and wake up at about the same time.

In humans, depending on the time of day, the physiological state, intellectual capabilities and mood change cyclically – all this depends on fluctuations in the concentration of hormones in the blood. Scientists have hypothesized that the brain contains a “circadian center” that governs the biological rhythms of health.

During the period of wakefulness, the body is mainly aimed at processing accumulated nutrients in order to obtain energy for an active daytime life, and during sleep, the accumulation of nutrients and tissue repair occurs. All these changes occur at the expense of the endocrine glands, which produce hormones.

Hormonal biorhythms

At night, the most important hormones are produced, which contribute to the processing of energy reserves, fats and the formation of muscle tissue – in other words, the body recovers at night.

From 21.30, the hormone melatonin begins to be produced. As soon as the pineal gland (pineal gland, located in the brain) begins to intensively produce it, a person’s body temperature drops, many processes slow down, a feeling of drowsiness appears, and soon we fall asleep. But since this hormone is intensely destroyed by light rays, it is important to fall asleep in complete darkness.

In addition to the sleep hormone, somatotropic hormone (growth hormone) is also produced at night, which is involved in recovery processes. It is especially necessary for breaking down fat and increasing muscle mass.
Growth hormone is the main fat burning hormone, it is produced from 11 pm to 1 am, in addition, it helps to increase protein synthesis, which leads to muscle growth, renewal of the skin and tissues of internal organs, – explains nutritionist Elena Kokoreva.

Lack of this hormone leads to decreased performance and increased fat accumulation in the abdomen.

Morning comes, and nighttime hormones are replaced by daytime hormones, which are produced in the adrenal glands at about four o’clock in the morning, long before waking up, thus preparing the body for wakefulness. The most active is cortisol (a hormone of vigor and energy): its peak concentration is reached by six or seven in the morning. If a person does not get up at a certain time, then cortisol turns into a stress hormone. In order to prevent this, you need to wake up before seven in the morning, thereby relieving yourself of unnecessary stress.

Researchers believe that we have different clocks that govern biological processes in the liver, intestines, and even the heart. The theory of circadian rhythms is not new, but at the World Health Summit in March, experts predicted that circadian rhythm diets would be trending this year. Why? For starters, we live in the digital age: blue light from phones, daily Zoom meetings, overeating (thanks to the TV shows we sometimes watch until the early morning hours) are damaging our natural circadian rhythms.

Biorhythms of nutrition

According to the expert, the diet has a huge impact on the processes of digestion and assimilation of food, as well as on the state of the body as a whole. Deviation from it can lead to significant weight gain. Therefore, the diet should be selected taking into account the body’s biorhythms and physiological processes.

What is the circadian diet

In short, you need to eat large portions at the beginning of the day, and the last meal should be light and not late. The circadian diet is a lot like intermittent fasting, but it’s important when you eat your meals.


The best time for breakfast is from 6.00 to 7.30, at which time intestinal peristalsis is activated, the secretion of gastric juice increases.

Breakfast should be the main food of the day: dense and rich, rich in fiber, lean protein and healthy fats. Proteins, fats and carbohydrates at this time are broken down as much as possible and processed into energy. Load up on avocados, eggs, and slow carbs (oatmeal, buckwheat, or quinoa).

If you eat breakfast from six to eight in the morning, you can be sure that all the food will be digested, and nothing will be deposited in the “fat reserves”. This is especially important for people who dream of losing weight, – said Elena Kokoreva.

The feeling of hunger in many people occurs by 11.00, especially among those who eat according to the biological clock: gastric juice is actively produced, it is at this time that the body needs to be fed with so-called fast carbohydrates (fruits and berries will provide the body with energy for further activity).


From one to three in the afternoon, you can start lunch. At about 13.00, the peak of the activity of the digestive system occurs, there is a rapid release of digestive juices, so food is digested and absorbed in the best way. Lunch should include proteins, carbohydrates, fiber, the right fats.

The food intake should not be too abundant, so as not to cause a feeling of heaviness and not lead to significant levels of insulin in the blood. You can make chicken soup with vegetables, and for the second – lentils or other legumes. For a snack, try boiled eggs, a handful of raw nuts, or fruit.

As the expert explains, the first peak of insulin occurs at 16-17 hours: this is the time when you want sweets most of all. At this moment, instead of something harmful, we will offer the body a protein product in the form of cottage cheese, 2-5% fat. He will satisfy the desire to eat another chocolate bar and saturate the body until the evening meal.


Dinner should be no later than 7:30 pm (4 hours before bedtime) and should consist of protein, low glycemic index (GI) carbohydrates and fiber.

For dinner, you can eat chicken, eggs, natural or Greek yogurt, fish (salmon). For vegetarians, good sources of protein include, for example, quinoa, lentils, nuts, whole grains, and legumes. But starchy vegetables (potatoes) and rice are best avoided.

The second peak of insulin release occurs at 21 hours, it is after this time that the pancreas closes and the gastrointestinal tract prepares for sleep.


As for drinks, the expert recommends avoiding coffee and alcohol if possible, since they can disrupt the work of the biological clock. Try to drink eight glasses of clean water every day.

Remember to eat slowly, chewing food thoroughly. Drink only very dry food, it is better to drink no earlier than an hour after eating. Water dilutes stomach acid, making it difficult for digestion and causing food to ferment in the stomach and intestines.

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