Study analyzes the health benefits of time-restricted eating

Time-restricted eating (TRE) is a dietary regimen in which eating is restricted to particular hours. It has received great attention in weight-loss circles. Recent research by Salk scientists demonstrates that TRE provides multiple health benefits in addition to weight loss. The research also indicates that these benefits may depend on age and sex.

A new study by Salk scientists shows that time-restricted eating (TRE) confers multiple health benefits besides weight loss. The study also shows that these benefits may depend on sex and age. Video Credit: Salk Institute.

A majority of the studies on TRE concentrate on weight loss in young male mice; however, Salk researchers wanted to ascertain the additional benefits of TRE on other populations. Their results were published on August 17^th, 2021, in the journal Cell Reports.

The results demonstrate that while sex and age do impact the effects of TRE, the eating tactics deliver many health benefits for young and old of both sexes, demonstrating that TRE may be a useful intervention for fatty liver disease, type 2 diabetes, and liver cancer, as well as infectious diseases like COVID-19, in humans.

For many TRE clinical interventions, the primary outcome is weight loss, but we’ve found that TRE is good not only for metabolic disease but also for increased resilience against infectious diseases and insulin resistance.”

Satchidananda Panda, Professor, Regulatory Biology Laboratory, Salk Institute

Satchidananda Panda is the holder of the Rita and Richard Atkinson Chair.

Glucose intolerance is the early step on a slippery slope to nonalcoholic fatty liver disease and liver cancer—one among the few cancers whose prevalence and death rates has increased, instead of declining, in the past 25–30 years.

Moreover, over 40% of Americans are already diabetic or prediabetic, with the American Diabetes Association anticipating 1.5 million new cases each year. These facts make identifying a simple treatment for glucose intolerance a key priority.

Violating the traditional young-male-mice mold, the scientists fed a high-sugar, high-fat diet to male and female mice of two age groups (similar to 20- and 42-year-old humans), limiting eating to 9 hours a day.

The researchers ran tests to confirm how age and sex impact the outcomes of TRE on a range of health parameters—glucose regulation, fatty liver disease, muscle mass performance and endurance, and survival of sepsis (a life-threatening response to infection).

The researchers also took the rare step of comparing their lab conditions to the animals’ circadian clocks (mice sleep during the day and wake up at night), often working through night-vision goggles and specialized lighting.

The team examined the tissues of mice on TRE to confirm their chemical makeup and discovered that despite sex, age, or weight loss profile, TRE strongly protected against fatty liver disease, a state that affects around 100 million Americans and for which no medicine has been approved.

This was our first time studying female mice, and we weren’t sure what to expect. We were surprised to find that, although the females on TRE were not protected from weight gain, they still showed metabolic benefits, including less-fatty livers and better-controlled blood sugar.”

Amandine Chaix, Study First Author and Assistant Professor, University of Utah

Amandine Chaix was a former staff scientist at the Panda lab.

Oral glucose tolerance tests given to mice after 16 hours of fasting showed that TRE was linked with a lower increase in blood glucose and a quicker return to normal blood sugar levels in both young and middle-aged males, with a substantial improvement in glucose tolerance in young and middle-aged females.

Likewise, middle-aged females and males on TRE were able to restore normal blood sugar levels more effectively than control mice, who had food accessible at all times. The results demonstrate that TRE may be an inexpensive or no-cost, easy-to-use means to treat or prevent diabetes, and supports the findings of the laboratory’s 2019 study on TRE for metabolic syndrome in humans.

The scientists also identified that TRE may defend both males and females from sepsis-induced death—a specific danger in ICUs, particularly during the pandemic. They administered a toxin that caused a sepsis-like condition in the mice and tracked survival rates for 13 days. They discovered that TRE protected both female and male mice from dying of sepsis.

TRE did not just protect against diabetes, fatty liver disease, and death from sepsis; it also allowed male mice to protect and add muscle mass and also enhance muscle performance (the effect did not hold for females). This finding is exceptionally important for the elderly, for whom enhanced muscle performance can help safeguard against falls.

This overwhelming finding points to the next steps and new questions for Panda’s lab—Does muscle mass increase as TRE helps muscles repair and regenerate better? What is the effect of TRE on muscle metabolism and regeneration?

These are very exciting questions for us, and we look forward to studying them in more detail.”

Satchidananda Panda, Professor, Regulatory Biology Laboratory, Salk Institute