What You MUST Know About Your Circadian Clock and Intermittent Fasting. You are not just what you eat, it’s when you eat that can have risks or benefits. When you eat and snack at irregular times of the day you can disrupt the biological clocks in every cell and organ in your body.

Molecular clocks are present in almost every cell of our body. These timekeeping mechanisms are present in almost every brain region and peripheral organ regulating hunger, digestion, absorption, nutrient metabolism, as well as fat storage and utilization. Metabolism has to adapt to switch between nutrient storage during periods of availability and the use of stored nutrients during periods of fasting. Eating schedules also affect other organs and their clocks.

Understanding the circadian rhythm of these clocks is helping us understand how timing of our eating may affect body weight, body composition, blood sugar regulation, lipid levels, the gut microbiome, cardiac function, inflammation, sleep, and overall health. These clocks anticipate daily recurring and predictable changes to adapt cellular functions. When and how much you eat can affect those clocks so timing makes a difference.

Are your clocks in sync or are they disrupted?

gears in formation of a human head within a clock to represent circadian rhythm

Disrupting your biological clocks can have dire consequences.

Circadian Rhythm Disruptions (CRD) can increase risks for noninfectious chronic diseases, including:

High blood sugar and weight gain

  • Blood sugar remains relatively higher in the evening or late night than in the morning.
  • Melatonin suppresses insulin release.
  • A 6-hour daily interval (from 8:00 a.m. to 2:00 p.m.) for 5 weeks was able to improve insulin sensitivity, pancreas β cell responsiveness (the cells that make insulin), blood pressure, oxidative stress, and appetite.
  • This suggest that consuming more calories early in the day may be preferred for better blood sugar regulation and weight control.

Cardiovascular diseases

  • Multiple studies have demonstrated that shift workers who experience circadian rhythm disruption are at an increased risk for metabolic syndrome, cardiovascular disease, stroke, and type 2 diabetes.
  • Erratic eating patterns such as eating over a prolonged period per day and irregular meal timing are common in patients with metabolic syndrome.
  • Human studies showed that intermittent fasting often referred to as time restricted eating is effective in improving metabolic health by lowering weight, fat mass, blood pressure, triglyceride levels, and markers of oxidative stress.

Gastrointestinal disorders

  • Humans have a daily rhythm in the production of saliva, gastric acids, digestive enzymes, and bile salts, and all decline late at night. There is also a daily rhythm in gut motility and the composition and function of the gut microbiome, which has an impact on your metabolic, hormonal, nervous and immune systems.
  • Colonic movement (peristalsis) increases in the early morning and contractions decrease at night.
  • The nightly rise in growth hormone occurs with the nightly rise in mucus secretion in the gut lining to repair and maintain the gut lining.
  • Maintaining the gut lining is essential to prevent potential food allergens and bacterial lipopolysaccharides (toxins that are harmful) from causing systemic inflammation.
  • Working with your circadian clocks supports the intestinal barrier function. In addition, guards against “leaky gut” digestive disorders and food sensitivities as well as maintains a healthy microbiome.

These are just a few things that timing of your eating has on your biological clocks. For example, it regulates different organs and systems. These clocks have an effect on your immune system, various forms of cancer, liver disease, depression and fat deposition. If your clocks are not in sync, you may suffer many consequences.

How to Keep Your Clocks in Sync

Circadian clock–driven eating behaviors optimizes nutrient utilization. Whereas disrupting the clock’s schedule compromises how food is processed. For instance, just working on the timing of when you eat and when you sleep can put you in or out of sync. Intermittent fasting or time-restricted eating (TRE) in which food is consumed within a consistent 8–12-h interval. Therefore, appears to sustain optimal nutrient utilization and promote health as well as keep your clocks in sync.

The Ideal Circadian Rhythm

A review article in the Annual Review of Nutrition outlines an ideal circadian day for an average person:

  • 8 hours for sleep
  • Waiting for at least 1 hour after waking up before eating
  • At least 1 hour of exposure to bright light (1,000–10,000 lux) within the first half of the waking hour. However, to entrain the hypothalamic clock to ambient light and to suppress melatonin
  • Exposure to dim or blue-depleted light for 2–3 h prior to bedtime to build sleep pressure
  • No caloric ingestion for 2–3 h prior to bedtime.

Your hormones and sleep wake cycles have their own clocks and rhythms. If any of your clocks are out of sync, consult a functional medicine physician who can evaluate the various factors that can impact your weight, energy, mood, hormone and cardiovascular health and put your clocks in sync.