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Rx Nutrition Resource Center

Disclosures: Panda reports collecting royalties as the author of the book The Circadian Code.
September 23, 2021
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Time-restricted eating may help prevent, manage many cardiometabolic diseases

Disclosures: Panda reports collecting royalties as the author of the book The Circadian Code.
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Adopting a time-restricted eating schedule to align with a person’s circadian clock could help prevent diabetes, heart disease and other diseases, according to researchers.

Early clinical trials on time-restricted eating with people have shown promising results in reducing risks for multiple cardiometabolic disorders, and studies with mice have provided some mechanistic evidence behind the benefits of time-restricted eating, according to Satchin Panda, PhD, professor at the Salk Institute for Biological Studies in La Jolla, California.

Panda is a professor at the Salk Institute for Biological Studies in La Jolla, California.

“Aligning our daily schedule to our circadian clock has untapped potential to prevent, manage and reverse many chronic diseases,” Panda told Healio. “One simple approach to nurture an optimum circadian clock is to consume all daily calories to a consistent window of 8 to 10 hours. Preclinical animal studies and pilot human studies have shown time-restricted eating can have pleiotropic beneficial effects on several health conditions from obesity, prediabetes to diabetes, cardiometabolic diseases, cancer and dementia.”

Possible mechanisms in time-restricted eating

The concept of time-restricted eating stems from circadian rhythm disruptions, according to Panda and colleagues. Rodent studies have revealed that the timing of eating altered the expression of thousands of genes, resulting in several physiological, metabolic and behavior changes.

“First of all, it optimizes the timing of anabolic (building new biological molecules), catabolic (breaking down toxins and excessive nutrients such as fat) and repair (of DNA and other cellular damages), which brings balanced metabolism,” Panda said. “Time-restricted eating also optimizes the levels and function of several hormones, including insulin, adiponectin and leptin. Finally, it also improves sleep and thereby may improve many aspects of brain health.”

While few studies have examined the mechanisms behind time-restricted eating in humans, available evidence from rodent studies has shown time-restricted feeding activates pathways in the liver known to mediate the benefits of fasting, improves circadian rhythms, may have beneficial effects on adipose tissue and gut function, and may induce integrated stress response pathways to contribute to health benefits. Additionally, time-restricted eating earlier in the day is associated with the most benefits in endocrine regulators and appetite reduction.

Challenges implementing time-restricted eating

While time-restricted eating may have several metabolic benefits, there are several challenges with implementing the lifestyle. These barriers include evaluating a person’s lifestyle prior to adopting time-restricted eating, creating educational and informational programs to enable behavioral change and ensuring adherence to the eating pattern.

“Personal barriers relate to habits of very early morning or very late food and beverages, which raises some anxiety about adopting an 8- to 10-hour time-restricted eating window,” Panda said. “This personal barrier is mostly addressed by some education and suggestions on how to manage hunger or food craving. The interpersonal barriers relate to family dynamics where a person’s eating habit is tied to their loved ones. Often the interpersonal barriers also relate to someone caring for a shift worker or those wanting to share meals with their family members who may have different work, study or extracurricular activity schedules. The community/cultural barriers relate to cultural or community habits of eating too late at night or sharing meals late at night in a community setting for 2 or more nights every week. Finally, the work-related barriers are shift work and long working hours. Since about 20% of the workforce in industrialized nations and more than 25% of workforce in developing countries are shift workers who are typically excluded from lifestyle intervention studies and programs, this is a major barrier that may need policy level modification to enable a time-restricted eating lifestyle.”

There has been a huge increase in time-restricted eating clinical trials over the past 2 years. The duration of most interventions has been between 4 and 12 weeks. Panda and colleagues expressed concern that most studies did not assess eating windows during the intervention and may not have accurately measured the timing of food intake. They wrote that using a smartphone application to accurately track food intake could strengthen the findings of future trials.

The most common finding in completed trials has been a decrease in body weight. Twelve studies have reported improvements in glucose regulation, and others have reported cardiovascular benefits, with decreases in blood pressure being the most common factor.

“Importantly, time-restricted eating was found to be feasible and safe for all studies,” the researchers wrote. “Larger randomized control trials are needed as many of the studies to date are smaller pre-post or crossover trials. Yet, the replication of findings, even in diverse patient populations, speak to the potential impact of time-restricted eating as a health intervention.”

Future time-restricted eating clinical trials

While clinical trials on time-restricted eating have provided encouraging results so far, stronger studies are needed. The researchers noted most studies involve small cohorts and have been performed over a short period of time. Additionally, only a few studies have been randomized controlled trials or have rigorously assessed eating duration prior to the intervention. Additionally, Panda noted the molecular and cellular mechanisms of time-restricted eating are still unknown for specific tissue type and disease conditions.

“Most human studies on time-restricted eating are pilot or feasibility studies,” Panda said. “Larger clinical trials on people with different preexisting conditions and from different ethnicities are needed to find both feasibility of time-restricted eating in different disease conditions and magnitude of health benefits. Implementation research is needed to identify barriers and approaches to overcome these barriers.”

If beneficial findings are replicated in future trials, time-restricted eating could become a substantial lifestyle tool for many people, according to the researchers, with its modest effect on weight loss combined with other weight-loss independent effects possibly leading to improved public health and reduced health care costs.

For more information:

Satchin Panda, PhD, can be reached at panda@salk.edu.