Every year, millions of Nigerians willingly sign up to be hungry, not because there is no food but because faith demands it. This year is particularly striking because both major faith communities are fasting around the same period, creating a rare national moment where restraint, sacrifice, and discipline dominate public life.

But beyond the prayers, self-denial, and spiritual reflection, fasting is not only a religious ritual. Medical researchers say it triggers measurable changes in the body, affecting metabolism, hormones, brain function, and even cellular repair. In other words, while believers fast for spiritual reasons, the body is also undergoing a complex biological process that experts say can be beneficial when done properly.

What happens inside the body during fasting

Medical researchers say controlled fasting gives the body a break from constant digestion and allows it to switch into repair mode. During fasting, insulin levels drop, and the body begins to use stored energy, a process linked to improved blood sugar control and fat metabolism. Studies from institutions including Harvard Medical School note that structured fasting patterns can support weight management and reduce risk factors for metabolic diseases such as type 2 diabetes and heart conditions.

Scientists also point to a cellular clean-up process known as autophagy, where the body recycles damaged cell components. This mechanism, first widely recognised through Nobel Prize-winning research in 2016, is associated with healthy ageing and disease prevention. When food intake pauses for long enough, the body shifts from growth to maintenance, repairing tissues and clearing out cellular waste.

Fasting may also influence inflammation, a key driver of many chronic illnesses. Reviews published by the National Institutes of Health suggest that intermittent fasting can reduce inflammatory markers and improve cardiovascular health indicators in some individuals. For populations facing rising rates of hypertension and diabetes, this benefit is particularly relevant.

Mental effects are often reported too. Many fasters describe heightened focus, emotional calm, and improved discipline after the initial hunger phase passes. Researchers believe this may be linked to changes in brain chemicals and energy use, as the brain begins to rely more on ketones rather than glucose.

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However, experts emphasise that it is not universally beneficial. People with certain medical conditions, pregnant women, children, and those on specific medications may face risks without proper guidance. Hydration, balanced meals during non-fasting hours, and moderation remain essential.

Nigerian health authorities have also echoed this caution. During previous fasting periods, Lagos State health officials advised that individuals with chronic illnesses should consult medical professionals before undertaking prolonged fasting. According to Akin Abayomi, fasting can be safe for healthy adults but requires careful management for people with conditions such as diabetes, hypertension, or kidney disease, especially in hot climates where dehydration risk is higher.

For millions observing Ramadan and Lent, the practice therefore becomes more than a spiritual exercise. It is also a physiological reset that, when done responsibly, can support metabolic health, cellular repair, and mental clarity alongside its religious meaning.

Cynthia Nwanonyiri