Just about every week there’s a new story about intermittent fasting – known as time-restricted eating (TRE) – and whether it’s a viable or even superior strategy for losing weight.
TRE is when your eating is confined to a strict window, usually eight hours a day. Aside from managing weight gain, there is growing evidence that TRE protects the liver.
University of Sydney researchers last year said they were investigating “how intermittent fasting works on the liver to help prevent disease”.
A new intensive study from The Salk Institute has made a big splash, confirming that there are multiple health benefits from TRE aside from weight loss.
The catch? The benefits are not equally parcelled out. Some are dependent on age and sex.
The most awkward finding? TRE protects against weight gain in young and old males, but not in females.
Could the researchers be wrong? This was a study done with mice. We’ll get back to that.
To all women who’ve committed to intermittent fasting, the researchers found that you haven’t wasted your time – but should perhaps stick with TRE for its other advantages
So what’s the good news for everybody ?
The Salk study found that TRE could be “a valuable intervention” for type 2 diabetes, fatty liver disease and liver cancer.
There was good news for elderly males. TRE extends muscle performance and motor coordination – which means you’re at less risk of losing your balance and falling over.
Probably the most startling finding was that TRE could promote resilience against infectious diseases.
For older people, TRE improves their chances of surviving sepsis or ‘blood poisoning’. Sepsis has to be diagnosed quickly, before it causes organ failure and death.
All of these findings require further investigation. At the least, the researchers have opened up some impressive lines of enquiry.
Fingers crossed the research holds up
That this was a mouse study will cause some readers to groan. There is plenty of resistance in the wider world to the idea that what happens in lab-altered mice can be translated to the human population.
Sometimes it can’t. It depends on the kind of research. But there is good evidence that experiments using mice in metabolism and obesity research hold up.
However, there is a convention that young male mice models are used in research. According to a prepared statement, the Salk researchers ditched this convention.
In their experiment, they fed a high-fat, high-sugar diet to male and female mice of two age groups (equivalent to 20- and 42-year-old humans), restricting eating to nine hours per day.
The team ran tests to ascertain how age and sex affect the outcomes of TRE on a variety of health parameters: fatty liver disease, glucose regulation, muscle mass, performance and endurance, and survival of sepsis, a life-threatening response to infection.
They also took the rare step of matching their lab conditions to the animals’ circadian clocks. Mice sleep during the day and rise at night – which meant that the researchers were often working via night-vision goggles and specialised lighting.
Analysing the mouse-model tissues, the researchers found that “regardless of age, sex or weight loss profile, TRE strongly protected against fatty liver disease”.
“This was our first time studying female mice, and we weren’t sure what to expect,” said first author Amandine Chaix, an assistant professor at the University of Utah.
“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.”
That TRE enabled older male mice to preserve and add muscle mass and improve muscle performance somewhat baffled the researchers.
“Does muscle mass increase because TRE helps muscles repair and regenerate better? What is the impact of TRE on muscle metabolism and regeneration?” said Satchidananda Panda, the study’s corresponding author.
“These are very exciting questions for us, and we look forward to studying them in more detail.”