Satchin Panda is a professor in Salk’s Regulatory Biology Laboratory. He explores the genes, molecules and cells that keep the whole body on the same biological clock, also known as a circadian rhythm. On this episode of Where Cures Begin, Panda talks about what a biological clock is, how living in sync with your clock can improve your health, and how growing up in India informed his research.
From iScience / Cell.com (June 26, 2020):
…the beneficial effects of TRE are dose dependent, with greater reductions in body weight, fat mass, and improvement in glucose tolerance when a 9-h protocol was implemented versus 12 and 15 h. The optimal TRE time frame to recommend for people has not been tested. Clear improvements have been noted after 6-, 8-, 9-, and 10-h protocols. It is likely that the greater time restriction would result in greater weight losses, which may maximize the metabolic benefits.
Eating out of phase with daily circadian rhythms induces metabolic desynchrony in peripheral metabolic organs and may increase chronic disease risk. Time-restricted eating (TRE) is a dietary approach that consolidates all calorie intake to 6- to 10-h periods during the active phase of the day, without necessarily altering diet quality and quantity.
TRE reduces body weight, improves glucose tolerance, protects from hepatosteatosis, increases metabolic flexibility, reduces atherogenic lipids and blood pressure, and improves gut function and cardiometabolic health in preclinical studies. This review discusses the importance of meal timing on the circadian system, the metabolic health benefits of TRE in preclinical models and humans, the possible mechanisms of action, the challenges we face in implementing TRE in humans, and the possible consequences of delaying initiation of TRE.
Human biology is tuned to a 24-hour light-dark cycle but modern lifestyles are disrupting it with unhealthy consequences, says Linda Geddes
From a PLOS Biology Journal study (Feb 20, 2020):
The major finding of this study is that the timing of feeding over the day leads to significant differences in the metabolism of an equivalent 24-h nutritional intake. Daily timing of nutrient availability coupled with daily/circadian control of metabolism drives a switch in substrate preference such that the late-evening Snack Session resulted in significantly lower LO compared to the Breakfast Session.
Developed countries are experiencing an epidemic of obesity that leads to many serious health problems, foremost among which are increasing rates of type 2 diabetes, metabolic syndrome, cardiovascular disease, and cancer. While weight gain and obesity are primarily determined by diet and exercise, there is tremendous interest in the possibility that the daily timing of eating might have a significant impact upon weight management [1–3]. Many physiological processes display day/night rhythms, including feeding behavior, lipid and carbohydrate metabolism, body temperature, and sleep.
These daily oscillations are controlled by the circadian clock, which is composed of an autoregulatory biochemical mechanism that is expressed in tissues throughout the body and is coordinated by a master pacemaker located in the suprachiasmatic nuclei of the brain (aka the SCN [1,4]). The circadian system globally controls gene expression patterns so that metabolic pathways are differentially regulated over the day, including switching between carbohydrate and lipid catabolism [1,3,5–9]. Therefore, ingestion of the same food at different times of day could lead to differential metabolic outcomes, e.g., lipid oxidation (LO) versus accumulation; however, whether this is true or not is unclear.
From a MedPageToday.com online article (March 2, 2020):
“Dysfunctional sleep likely is by far the most prevalent comorbidity in CVD. This makes it essential to explore the nature of sleep, but this is reliant on the enthusiasm of clinician scientists,” according to the editorialists.
“In modern society, both the quantity and quality of sleep are negatively influenced by factors such as longer hours of work, more shift work, artificial light and cell phones, all leading to self-reported daytime symptoms such as fatigue, tiredness, and sleepiness,”
A larger range in individual sleep duration and sleep timing across 7 days of wrist actigraphy was associated with significantly more CVD events over a median 4.9 years of follow-up (P=0.002 for both trends).
From a Technology Networks online article:
By comparing the pancreatic cells of type 2 diabetic human donors with those of healthy people, researchers at the University of Geneva (UNIGE) and at the University Hospitals of Geneva (HUG), Switzerland, were able to demonstrate, for the first time, that the pancreatic islet cells derived from the Type 2 Diabetic human donors bear compromised circadian oscillators.
The disruption of the circadian clocks was concomitant with the perturbation of hormone secretion. Moreover, using clock modulator molecule dubbed Nobiletin, extracted from lemon peel, the researchers succeeded in “repairing” the disrupted cellular clocks and in partial restoring of the islet cell function. These results, published in the Proceedings of the National Academy of Sciences of the United States, provide a first insight into innovative approach for diabetes care.
The circadian clock system (from Latin “circa diem”, about a day) allows the organisms to anticipate periodical changes of geophysical time, and to adjust to these changes. Nearly all the cells in our body comprise molecular clocks that regulate and synchronize metabolic functions to a 24-hour cycle of day-night changes.
Today, increasing evidence show that disturbances in our internal clocks stemming from frequent time zone changes, irregular working schedules or ageing, have a significant impact on the development of metabolic diseases in human beings, including type-2 diabetes. Such disturbances seem to prevent the proper functioning of the cells in the pancreatic islet that secrete insulin and glucagon, the hormones that regulate blood sugar levels.
From a NeuroscienceNews.com online release article (01/02/20):
During the years 1976 through 1980, 15% of U.S. adults were obese. Today, about 40%of adults are obese. Another 33% are overweight.
“But, of course, food is now abundant, and our next meal is as close as the kitchen, or the nearest fast-food drive-through, or right here on our desk. Often, these foods are high in fats, sugars, and therefore calories, and that’s why they taste good. It’s easy to overconsume, and, over time, this takes a toll on our health.”
In a study published Thursday in the journal Current Biology, Güler and his colleagues demonstrate that the pleasure center of the brain that produces the chemical dopamine, and the brain’s separate biological clock that regulates daily physiological rhythms, are linked, and that high-calorie foods – which bring pleasure – disrupt normal feeding schedules, resulting in overconsumption. Using mice as study models, the researchers mimicked the 24/7 availability of a high-fat diet, and showed that anytime snacking eventually results in obesity and related health problems.
From a Sleep Review Magazine online article:
When people are awake during the night, their behaviors are often mismatched with their internal body clocks. This can lead to nighttime eating, which can influence the way the body processes sugar and could lead to a higher risk in diabetes. “What happens when food is eaten when you normally should be fasting?” Scheer asked the audience. “What happens is that your glucose tolerance goes out the window….So your glucose levels after a meal are much higher.” This can increase people’s risk for diabetes.
Frank Scheer, PhD, professor of medicine at Harvard Medical School and director of the medical chronobiology program at Brigham and Women’s Hospital in Boston, says disruption of the body’s circadian rhythms may be one major reason why more Americans are living with preventable diseases. During his keynote talk at the 2019 AAST annual meeting in St. Louis, he outlined how recent research supports the hypothesis that higher rates of shiftwork and other forms of nighttime disruption could be contributing to increased rates of obesity, diabetes, and other common ailments.