New Study: Time Restricted Eating Has Health Benefits Beyond Weight Loss

A new study from the famed Salk Institute shows that Time-Restricted Eating (TRE), popular as a weight-loss strategy, also has significant health benefits – from disease prevention to helping people survive infections such as COVID-19. While some of the benefits depend on gender and age, the shocking findings indicate that TRE could be used as an inexpensive treatment for some of the most common conditions afflicting Americans, since it improves glucose metabolism, boosts immune response, and lowers inflammation.

We know that using intermittent fasting – another way of thinking about time-restricted eating where you eat all your calories during a limited window of time and then fast for the rest of the day or night – can help people lose weight. But this new study has found that it also has health benefits that are varied and significant. The use of TRE as a strategy may help reduce the risk of type 2 diabetes, fatty liver disease, and even liver cancer, and there is some evidence that it can help treat infectious diseases such as COVID-19.

Time-restricted eating (TRE) is defined as a dietary regimen that restricts eating to specific hours of the day, and then fasting the rest of the time. TRE has become extremely popular for weight loss since it reduces blood sugar levels during the fasting hours, and forces the body to pull fat from storage to be used as fuel once the body's available energy (such as glycogen stored in the liver, muscles, and other cells) is used up.

In the study, researchers fed a high-fat, high-sugar diet to male and female mice that were the equivalent in age to 20- and 42-year-old humans, restricting their food intake to nine hours. Checking how TRE impacted fatty liver disease, glucose regulation, muscle mass, performance, and endurance, as well as the survival of sepsis, they were curious to see if there was a difference in the benefits to the male versus female mice. The study also aligned to the animals' circadian clocks – since mice generally sleep during the day and are active and eat at night (which is why you rarely see them in your kitchen).

Here were the surprising findings: TRE offered significant protection against fatty liver disease, regardless of the age or gender of the animals tested. This is significant because fatty liver disease affects more than 80 million Americans alone, according to the CDC.

"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," according to one of the study's authors, Amandine Chaix, who worked at the Salk lab that conducted the research, and is now Assistant Professor, Nutrition & Integrative Physiology Department, University of Utah. She was quoted in the journal Cell Reports.

TRE (the study called in TRF for Time-Restricted Feeding) was associated with better blood glucose tolerance than the mice in the control group, which makes this strategy an effective, drug-free way of treating pre-diabetes or diabetes, as well as metabolic syndrome, which the CDC says has reached epidemic proportions in the US.

The mice on the restricted feeding schedule also ended up having better motor performance, body composition, metabolic health, and overall fitness, although the male mice showed more improvements in these areas than the female mice. The study author concluded: "In males, TRF improved all metabolic and performance parameters tested, regardless of age, suggesting that TRF could improve healthspan and lifespan even with a Western diet feeding."

The conclusion in Cell Response explained: "Future studies of lifelong TRF will test this hypothesis. Finally, we show that being on TRF can increase survival to a septic challenge in middle-aged male mice, with a trend in females. This is especially relevant in the context of the COVID-19 pandemic during which this paper was written since poor metabolic health is the major risk factor for severe COVID-19."

Studies have shown that not eating for long stretches can activate the body's natural immune response, according to Dr. Jason Fung, author of Life in the Fasting Lane and The Cancer Code. Dr. Fung has written extensively on the subject of fasting and immunity, as well as how fasting can benefit the body's response to knocking out cancer cells, viruses and other lurking dangers that the immune system needs to respond to daily.

Intermittent fasting has been shown in the past to help the body heal by triggering what's known as "autophagy," or the self-cleaning mechanism that allows the immune cells to span out around the body and search for possible invaders, including damaged or dead cells, broken-off bits that are in need of disposal, and some of those can be from viruses and bacterial infections.

"Autophagy plays a key role in helping the body fight viruses," Dr. Fung told The Beet. "It's like a cleaning crew that comes in and scrubs the entire place, while you're sleeping. When the immune system sees signs of invading viruses or infection it sends the alarm bells of the immune system ringing and begins to create antibodies that will "recognize" this invader and be able to fight it off.

By fasting, or restricting your eating time to a small specific window, all the usual distractions that come with ingesting food get turned off, allowing the immune system to perform its necessary house cleaning and surveillance work, Dr. Fung explains, so the immune system doesn't have to deal with any potentially toxic elements or harmful bacteria that might be coming in with your food and can focus on the actual dangers such as cancer growth or viral infections that may be harboring in place.

The study from the Salk Institute also showed that the mice in the TRF group were able to survive the dangers of sepsis, a potentially fatal condition related to infection, where the body's inflammation response can trigger a runaway chain of events, which is especially relevant in the fight against severe cases of COVID-19.

To improve blood glucose tolerance, reduce the symptoms of metabolic syndrome and even lower inflammation, and possibly help treat symptoms of COVID-19, using time-restricted eating may be worth trying, according to a new study that looked at the effects on male and female mice given a Western diet. The results showed different benefits for males and females, however, so more study is needed.

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