Can fasting improve brain health, Neurologist explains effects of intermittent fasting

For weight loss, one common approach is to burn more calories than you consume, which often means practising portion control.

Beyond simply reducing meal size, many people are turning to time-restricted eating patterns such as intermittent fasting or one meal a day (OMAD), where there are defined windows for eating and fasting. The idea behind it is that during fasting periods, the body taps into stored fat and burns it for energy.

There has been a surge in these types of diets as more people prioritise weight loss goals. But amid these diet trends, an important question comes up: how does fasting impact your brain health? Cognitive functions, including attention span and decision-making skills, are important for day-to-day functioning. So, what does fasting actually mean for your brain health and overall cognitive performance?

HT Lifestyle reached out to Dr Nilesh Chaudhary, consultant neurologist at Dr L H Hiranandani Hospital, Powai, who shared his insights on the various ways fasting may affect brain health and highlighted which vulnerable groups need to exercise caution.

How does fasting impact brain health?

One of the ways fasting may affect brain health is by influencing neuroplasticity and neurodegeneration, as highlighted by the neurologist. He added, "Current evidence supports the hypothesis that structured fasting regimens may enhance neuroplasticity and reduce risk factors associated with neurodegeneration. In fact, he acknowledged that yes, fasting, especially intermittent fasting and time-restricted eating patterns, may cause a neuroprotective effect through major metabolic and molecular adaptations.

For the uninformed, neuroplasticity is the brain's ability to learn, adjust and rewire, while neurodegeneration, which is the loss of neurons, gradually pave way to neurodegenerative ailments like Alzheimer's. So, it indirectly suggests that fasting helps reduce the risks of these neurodegenerative diseases.

A process occurs when you are fasting, called metabolic switching. Dr Chaudhary explained, "One primary mechanism involves 'metabolic switching,' in which glycogen depletion shifts energy utilisation from glucose to ketone bodies. Ketones such as beta-hydroxybutyrate not only provide efficient neuronal fuel but also function as signalling molecules that upregulate brain-derived neurotrophic factor (BDNF), which plays a role in synaptic plasticity, learning, and memory consolidation."

In simple words, it means that as you fast, your body utilises the stored sugar (glycogen), and when that goes down, your body switches to burning fat for energy. Now, when the fat is utilised for energy and broken down, ketones are produced, which become an alternative 'neutral fuel' for the brain. In the end, brain cells have better connectivity, which causes improved learning and memory.

Who should be more careful?

But not everyone will benefit from fasting, especially those who are already medically vulnerable. There are some added risks. The neurologist listed certain high-risk groups, including those with diabetes, eating disorders, fraility and those on glucose-lowering medications. These people need to exercise precautions, especially when fasting, because they are more sensitive in certain ways.

Why? He reasoned that for those with diabetes, "They suffer increased risk of hypoglycemia and adverse outcomes." This means fasting can cause their blood sugar to drop too low, which leads to dizziness, shakiness, confusion, or rapid heartbeat and other serious health issues. Cognitive skills take a hit during this time.