This raises a pressing question: can we reap the health rewards of fasting without sacrificing our mental edge? To find out, we conducted the most comprehensive review to date<\/a> of how fasting affects cognitive performance.<\/p>\n People performed just as well on cognitive tests measuring attention, memory and executive function whether they had eaten recently or not. (ABC News: Danielle Bonica)<\/p>\n What’s the point of fasting?<\/p>\n Fasting is not just a trendy diet hack. It taps into a biological system honed over millennia to help humans cope with scarcity.<\/p>\n When we eat regularly, the brain runs mostly on glucose, stored in the body as glycogen. But after about 12 hours without food, those glycogen stores dwindle.<\/p>\n At that point, the body performs a clever metabolic switch<\/a>: it begins breaking down fat into ketone bodies (for example, acetoacetate and beta-hydroxybutyrate), which provide an alternative fuel source.<\/p>\n This metabolic flexibility, once crucial for our ancestors’ survival, is now being linked to a host of health benefits<\/a>.<\/p>\n What happens in your body when you fast?<\/a><\/p>\n We asked Mark Mattson, an American neuroscientist who has studied intermittent fasting for the last 25 years to see what goes inside our body when we are fasting.<\/p>\n Some of the most promising effects of fasting come from the way it reshapes processes inside the body. For instance, fasting activates autophagy<\/a>, a kind of cellular “clean-up crew” that clears away damaged components and recycles them, a process thought to support healthier ageing.<\/p>\n It also improves insulin sensitivity<\/a>, allowing the body to manage blood sugar more effectively and lowering the risk of conditions such as type 2 diabetes.<\/p>\n Beyond that, the metabolic shifts triggered by fasting appear to offer broader protection, helping reduce the likelihood<\/a> of developing chronic diseases often associated with overeating.<\/p>\n What our research showed<\/p>\n These physiological benefits have made fasting attractive. But many hesitate to adopt it out of fear their mental performance will plummet without a steady supply of food.<\/p>\n To address this, we conducted a meta-analysis, a “study of studies”, looking at all the available experimental research that compared people’s cognitive performance when they were fasting versus when they were fed.<\/p>\n Our search identified 63 scientific articles, representing 71 independent studies, with a combined sample of 3,484 participants tested on 222 different measures of cognition. The research spanned nearly seven decades, from 1958 to 2025.<\/p>\n After pooling the data, our conclusion was clear: there was no meaningful difference in cognitive performance between fasted and satiated healthy adults.<\/p>\n People performed just as well on cognitive tests measuring attention, memory and executive function whether they had eaten recently or not.<\/p>\n Fasting is not a one-size-fits-all practice, sometimes caution is warranted. (Supplied: iStockphoto\/bopav)<\/p>\n How fasting affects the mind<\/p>\n Our analysis did reveal three important factors that can change how fasting affects your mind.<\/p>\n First, age is key. Adults showed no measurable decline in mental performance when fasting. But children and adolescents did worse on tests when they skipped meals.<\/p>\n Their developing brains seem more sensitive to fluctuations in energy supply. This reinforces longstanding advice: kids should go to school with a proper breakfast to support learning.<\/p>\n<\/p>\n
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