This week heralds the beginning of Ramadan, a month of deep spiritual significance for Muslims across the globe. Over the next several weeks, followers of Islam will engage in reflection on values like spirituality, sacrifice, and patience. Central to this observance is fasting, which involves abstaining from all food and drink, including water, from sunrise to sunset.

While the spiritual gains of this discipline are paramount, fasting also impacts the body in various ways. Scientific research has highlighted several health benefits linked to this form of intermittent fasting. Certain strategies can ease the transition into this routine and enhance its positive effects.

To understand how intermittent fasting works, consider the human body as a hybrid vehicle. In our usual eating habits—consuming large meals, snacks, and drinks whenever we desire—we rely on immediate fuel sources. This fuel primarily consists of glucose derived from carbohydrates, comparable to a car using gasoline.

During fasting, however, the body’s ‘fuel tank,’ which is the liver and muscles where glucose is stored, begins to run low.

Once these reserves are depleted, typically after eight to twelve hours, the body shifts to its ‘electric mode,’ utilizing stored fat for energy. It’s akin to kickstarting an internal mechanism that signals, “Let’s burn some of this stored energy.”

This transition to a fat-burning state is facilitated by several crucial metabolic processes.

Your blood sugar drops, you produce less insulin (the hormone that signals your body to store fat) and the liver starts to produce ketones.

Ketones are like a super-efficient fuel source for the brain and muscles, derived from the breakdown of fat. The body quite literally turns into a lean, fat-burning machine.

A Muslim family gathers to celebrate the end of Ramadan. For the next month or so, worshippers will reflect on virtues such as spirituality, sacrifice and patience, as well as fasting – not eating or drinking anything (not even water), from dawn until sunset

This transition isn’t always easy; the first few days of fasting can be pretty torrid – you may feel extremely tired and most likely more hungry.

This is partly due to the initial drop in blood sugar and the body adapting to using fat as its primary fuel source. There may also be headaches due to dehydration.

If you are fasting for Ramadan this can be a tricky month sleep-wise, too; when you start intermittent fasting some nights you’ll sleep soundly, others you’ll toss and turn. This is linked to changes in hormones such as melatonin and cortisol, which regulate sleep-wake cycles, influenced by the fasting state.

So, planning for this month of fasting is important – you want to enjoy it in the healthiest way possible – and continuing with unhealthy habits will make it more of a struggle.

Think about foods that will keep you full and energised.

This means a diet balanced with protein, complex carbohydrates and healthy fats.

For suhoor, the pre-dawn meal, this could mean foods such as overnight oats with nuts and berries. Avoid sugary treats just before the fast begins or you could experience dramatic blood sugar fluctuations and increased hunger.

Eating excessively at the evening meal could lead to digestive discomfort, especially if the meal is high in fat and processed carbohydrates; high-fat foods can slow digestion, leading to that uncomfortable overly full feeling – whilst processed carbs can also contribute to bloating and gas, as they’re quickly digested and ferment in the gut.

Managing water intake is also crucial.

You should be drinking the same amount between sunset and dawn that you would on a non-fasting day. Avoid coffee and tea as well – they’re diuretics which could lead to fluid loss later.

After five days or so, the body should start to adapt and this can, ultimately, lead to many health benefits.

Last year a study in Indonesia looking at the effect of Ramadan fasting on the weight and body composition of 137 healthy students aged between 19 and 22 years found they lost significant amounts of weight and body fat.

Fasting during Ramadan can have a positive effect on the gut, too, reducing bloating, pain and heartburn, according to a 2023 study published in the European Journal of Clinical Investigation.

It can also have a beneficial effect on lowering blood pressure, according to research in the Journal of the American Heart Association in 2021. It’s thought that this is because while fasting, the nervous system is in a more relaxed state, known as parasympathetic tone, although more research is needed.

There are also studies pointing to fasting lowering inflammation.

In one 2018 research review published in the Journal of Nutrition and Intermediary Metabolism, researchers assessed levels of cytokines – proteins that regulate inflammation in the body – in healthy adults before and after Ramadan.

Excessive levels of cytokines are linked with chronic inflammation, which can be linked to numerous health conditions, including cancer.

At the end of the study, the participants’ cytokine levels were significantly reduced which could provide a short-term protective effect on healthy people (it’s worth noting that anyone with chronic health conditions is not expected to fast and the health effects may be different in other groups).

Emer Delaney is a dietician based in London. She says that there are studies pointing to fasting lowering inflammation. Chronic inflammation can be linked to numerous health conditions, including cancer

There’s an effect on cognitive function, too.

According to a 2016 study carried out by King Saud University in Saudi Arabia, during fasting people’s ability to unconsciously shift attention between one task and another improved significantly.

Symptoms of mental health can also improve.

In a review of 20 studies published last year in the Journal Discover Psychology: 72.7 per cent, 66.6 per cent and 85.7 per cent of the studies reported reduced symptoms of depression, anxiety and stress, respectively – and 71.4 per cent experienced improved psychological wellbeing.

This is likely due to the spiritual practise itself, community connection, and the sense of accomplishment that comes with self-discipline.

There are downsides of this kind of intermittent fasting – people can become dehydrated, which is a risk for gallstones.

And inevitably after Ramadan, some will return to their usual lifestyle, leading to weight gain.

But by making the right dietary choices, this time can also be an opportunity for a change and a springboard to longer-term benefits for body and mind.

Emer Delaney is a dietician based in London