Time-restricted eating (TRE) involves a regular, 24-hour cycle of eating and fasting, with meals, snacks, and sugary drinks strictly limited to the same 8–10 hour window each day.
TRE is a form of intermittent fasting (IF) in which people can eat what they like during a set period but must fast for the rest of the time.
Scientists believe the TRE protocol improves health and well-being by reinforcing the body’s natural daily cycle of rest and activity, but how it works at a molecular level has been unclear.
A new study in mice shows that time-restricted feeding (TRF) influences the activity of genes in 22 diverse tissues all over the body, including the brain, heart, lungs, liver, and gut.
“Our results open the door for looking more closely at how this nutritional intervention activates genes involved in specific diseases, such as cancer,” senior author Satchidananda Panda, Ph.D., who holds the Rita and Richard Atkinson Chair at the Salk Institute for Biological Studies in La Jolla, CA, told Medical News Today.
The researchers report their results in Cell Metabolism.
Time-restricted eating: What are the benefits?
A 2022 review of research notes that pilot studies in humans suggest that the health benefits of TRE include improvements in obesity, diabetes, and cardiovascular disease. The diet may also improve sleep and mental health.
In addition, another recent study in mice found that the eating pattern may even have anticancer effects.
Crucially, the health benefits of TRE compared with eating at any time during the day appear to apply regardless of the total calories or types of food consumed.
Kimberly Gomer, RD, a dietitian and director of nutrition at Body Beautiful Miami in Miami, FL, said that TRE can reduce hunger as a result of lower insulin response and lead to weight loss.
“I have seen intermittent fasting work as an extremely effective tool for my clients who need to lose weight,” said “A huge plus is that it discourages mindless snacking, which is a problem for many,” she told MNT.
“Of course, what is being eaten must be considered, especially with those who have diabetes,” she said.
Time-restricted feeding changes gene expression
For the present study, Prof. Panda and his colleagues allowed a control group of mice to eat whenever they liked, while a second group only had access to food during a 9-hour period.
Both groups ate the equivalent of a western diet and consumed the same number of calories overall.
After 7 weeks, the researchers took samples from 22 organs and brain regions every 2 hours over a 24-hour period.
The samples included tissue from the stomach, intestines, liver, lungs, heart, adrenal gland, hypothalamus, kidney, and brain.
Compared with the control group, TRF changed overall gene expression (the rate at which genes generate proteins) or the rhythmic activity of around 80% of all mouse genes.
Effects on circadian rhythms
The TRF diet orchestrated daily fluctuations in gene expression across all the tissues studied in the mouse model. This reinforced the body’s circadian rhythms, which are its natural cycles of rest and activity.
“Circadian rhythms are everywhere in every cell,” explains Prof. Panda.
“We found that time-restricted eating synchronized the circadian rhythms to have two major waves: one during fasting, and another just after eating,” he says.
“We suspect this allows the body to coordinate different processes,” he adds.
Interestingly, TRF reduced the activity of genes that play a role in inflammation and increased the activity of those involved in autophagy — the recycling of old and damaged cell parts.
“Increased autophagy (only during the fasting period) is known to improve health by preventing and managing age-related diseases and increasing healthspan,” Prof. Panda said.
Increased inflammation and reduced autophagy are recognized hallmarks of biological aging.
Potential benefits for shift workers
Although shift work is unavoidable for many people, it’s associated with an increased risk of obesity, diabetes, heart disease, and cancer as a result of disruptions to the body’s circadian rhythms.
In theory, TRE could help to restore these rhythms and boost workers’ health and well-being.
In a recent clinical trial, Prof. Panda and his colleagues found that a TRE diet improved the physical and mental health of firefighters who work regular 24-hour shifts.
However, this kind of diet is likely to be beneficial for everyone, said Prof. Panda — not just shift workers.
TRE benefits in humans: An area of ongoing research
Prof. Panda said that the vast majority of adults in the United States have an “erratic” eating pattern, with meals, snacks, and sugary drinks consumed over more than 12 hours each day.
“TRF is known to improve gut microbiome, liver health, glucose regulation, muscle function (increased endurance capacity), sleep quality, cognitive function, and resilience against infectious diseases,” said Prof. Panda.
“Therefore, it applies to everyone to stay healthy and achieve their peak physical and emotional performance,” he added.
The study authors concluded:
“[Our study] will serve as important resource to explain the effects of TRF on pre-clinical animal models of chronic metabolic disorders, neurodegenerative diseases, and cancer, thus providing justification for ongoing and future clinical trials evaluating the efficacy of TRF in the prevention and management of chronic diseases.”
Prof. Panda said there are numerous ongoing studies on the benefits of TRE humans, including more than 150 studies examining the effects of TRE on:
* excess body weight
* type 2 diabetes
* high cholesterol
* heart disease
Limitations of TRF using mouse models
The authors of the new study note that it had some limitations.
In particular, the research involved only young male mice. The scientists write that TRF is known to affect physiology differently depending on the subject’s age and sex.
In addition, mice are nocturnal and feed at night, which may limit the applicability of the findings to humans.
“[M]any benefits observed in mice as a result of TRF seem to be realized in humans,” Dorothy Sears, Ph.D, professor of medicine at UC San Diego School of Medicine, told MNT.
“However, the evidence is still in the very early stages, supported primarily by small, under-powered (but promising) randomized controlled trials. Larger studies are underway,” she noted.
Written by James Kingland for Medical News Today, January 10, 2023
Fact checked by Jill Seladi-Schulman, Ph.D.