Yellow brain with grid and colorful shapes
.Getty / Andriy Onufriyenks

Time without food benefits the mind, not just the body


FOR THOSE WHO CAN’T FUNCTION WITHOUT BREAKFAST, the idea of fasting on purpose might be repellent. But going without food for more than a few hours between meals may be the key to safeguarding brain function over the long term.

Scientists are just starting to make sense of the complex mechanisms which underscore how the brain relates to what we put into — or leave out — of our bodies. But what we do know about the brain and undergoing prolonged periods without food is tantalizing for future research to dig into.

HERE’S THE BACKGROUND — There may be an evolutionary reason why fasting may benefit the brain. Mark Mattson is a professor of neuroscience at John’s Hopkins School of Medicine and has researched fasting and the brain extensively. He tells Inverse that humans originally evolved to go without food for extended periods of time.

“Individual brains had to function very well in a food-deprived state. Otherwise, they’re not going to be successful in acquiring food,” Mattson says.

“They have to have that to be alert, their cognition has to be really good because they have to figure out how to locate the food.”

Early humans crouched around a fire near a river
Our brain’s reaction to fasting may have to do with ancient humans who went for long stretches of time without food and had to stay alert to find it. Getty / Culture Club

Fasting triggers a shift in the resources your body uses for energy. Your metabolism moves from using glucose to ketones to power the body. Ketones are a type of acid produced by the liver from fat — interestingly, ketogenic diets rely on this shift, too.

But it’s not just fat-burning — the increased use of ketones during fasting periods and the switch back to use of glucose following eating is known as “metabolic switching.” In turn, this triggers a biological cascade in the body which scientists believe may build the brain’s resilience and productivity, and boost its support system.

“It is thought cells go into a survival and repair mode during the fasts, followed by growth and regeneration during the refeeding phase,” Matthew Phillips explains to Inverse. Phillips is a neurologist at Waikato Hospital in New Zealand and studies fasting and ketogenic diets and the brain. In his work, he sometimes uses these “metabolic strategies” as part of treatments for his patients.

Ultimately, evidence suggests four brain health effects linked to fasting:

  • Brain cell generation
  • Cognitive and psychological benefits
  • Resilience to neurological conditions
  • Slowing the effects of aging

These are four of the potential brain benefits of fasting, ranked in order of the strength of the evidence backing them:

4. FASTING MAY HELP CREATE MORE BABY BRAIN CELLS — Whether for set windows throughout the day, every other day, or longer, there’s reason to believe that fasting for extended periods may help generate new brain cells.

In one study published in 2019, groups of mice that were deprived of food every other day for windows of between 12 and 16 hours had higher levels of specific protein markers compared to mice that were not deprived. These markers indicate new brain cells were being made, according to the paper, suggesting that the fasting mice may have been making new brain cells more efficiently and at a faster rate than the control mice.

Ghrelin, the hormone which prompts us to eat, dials up during periods without food (to no one’s surprise). There is evidence to suggest this increase also spurs the creation of new brain cells. In a 2015 study, mice that ate every other 24 hours had higher levels of ghrelin than mice that ate when they wanted to. In turn, the researchers found the fasting mice had more markers of new brain cells in an area of their brain called the hippocampus than did their non-fasting counterparts.

The researchers went further in this study. They found that mice without any ghrelin in their bodies that also fasted every other day did not see an increase in new brain cells. Together, the findings suggest fasting-induced boosts in ghrelin play a crucial role in brain health. Mattson suspects the same processes might be at play in human brains, too, but there isn’t enough evidence so far to know this for sure…


F. Kaskais Web Guru

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