We were wrong about “fasting”! – ISNA

According to RCO News Agency, Have you ever worried that skipping breakfast might make you sloppy at work? Or does intermittent fasting make you irritable, distracted, and less productive? Snack ads warn us that you’re not yourself when you’re hungry, reinforcing the common belief that eating is essential to keeping your brain fresh.

This message is deeply woven into our culture, as we are told that constantly fueling our bodies is the secret to staying alert and efficient.

However, time-restricted eating and intermittent fasting have become very popular approaches to health over the past decade. Millions of people do it for long-term benefits, from weight management to improved metabolic health.

Of course, this method raises an important question; Can we reap the health benefits of fasting without sacrificing mental strength? To find out, David Moreau, associate professor of psychology at the University of Auckland, conducted the most comprehensive study to date of how fasting affects cognitive performance.

Why fast at all?

“Fasting” is not just a fad diet trick. This method takes advantage of a biological system that has been developed over millennia to help humans cope with food shortages.

When we eat regularly, the brain runs mostly on glucose stored in the body as glycogen, but after about 12 hours without food, these glycogen stores are depleted. At that point, the body makes a smart metabolic switch and starts breaking down fat into ketones, such as acetoacetate and beta-hydroxybutyrate, which provide an alternative fuel source.

This metabolic flexibility, once crucial to our ancestors’ survival, is now associated with a host of health benefits.

Some of the most promising effects of fasting come from the way it reshapes processes within the body. Fasting, for example, activates autophagy, a type of cellular scavenging that removes and recycles damaged components, a process thought to support healthier aging.

Fasting also improves insulin sensitivity, allowing the body to manage blood sugar more effectively and reducing the risk of diseases such as type 2 diabetes.

Beyond that, the metabolic changes induced by fasting appear to offer broader protection and help reduce the risk of chronic diseases often associated with overeating.

What the data showed

These physiological benefits make fasting attractive, but many are hesitant to adopt it for fear that their mental performance will decline without a constant supply of food.

To address this issue, the researchers conducted a meta-analysis of many studies in this area, reviewing all available experimental research that compared the cognitive performance of individuals in a fasted versus fed state.

Our search identified 63 scientific articles representing 71 independent studies with a combined sample of 3,484 participants tested on 222 different cognitive measures, Moreau says. This research lasted almost seven decades (from 1958 to 2025).

He added: Our conclusion after collecting the data was that there was no significant difference in cognitive performance between healthy adults who fasted and those who did not fast, and people performed well in cognitive tests that measured attention, memory and executive function, whether they had recently eaten or not.

The difference that “fasting” makes

The researchers’ analysis revealed three important factors that can change the way fasting affects our minds.

The first key feature is age is Adults showed no measurable decline in mental performance when fasting, but children and adolescents performed worse on tests when they skipped meals. Their developing brains appear to be more sensitive to fluctuations in energy supply, reinforcing the old advice that children should go to school with a good breakfast to learn better.

“Timing” also seems to make a difference. We found that longer fasting was associated with a smaller performance gap between fasting and fed states, the researchers say. This may be due to a metabolic shift to ketones, which can restore a steady source of energy to the brain when glucose is depleted.

Performance in fasters was worse when the tests were conducted later in the day, suggesting that fasting may enhance the natural decline in our circadian rhythms.

The type of test was also important. When cognitive tasks involved symbols or neutral shapes, fasted participants performed as well or sometimes even slightly better, but when tasks involved food-related cues, fasted participants faltered. Hunger doesn’t cause general brain fog, but when the temptation to eat is on our mind, it distracts us more easily.

“Fasting”; yes or no

For most healthy adults, the findings provide reassurance that intermittent fasting or other fasting protocols can be explored without fear of losing mental alertness.

Having said that, fasting is not a one-size-fits-all method. Caution is necessary with children and teenagers, as their brains are still developing and seem to need regular meals to function better.

Similarly, if your job requires you to be fully awake late in the day, or if you are constantly exposed to tempting food cues, you may find it more difficult to continue fasting.

However, for certain groups, such as those with medical conditions or special dietary needs, fasting is not recommended without professional guidance.

Ultimately, fasting is best thought of as a personal tool rather than a universal prescription, as its benefits and challenges will vary from person to person.

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