Ramadan, Lent: are religious fasts good for your health?

Fasting plays an important role in many religious customs around the world. In an interview given to Sunday Timesformer British Prime Minister Rishi Sunak (Hindu and vegetarian) explained that he practiced intermittent fasting regularly, starting each week with 36 hours of fasting, which he considers an “important discipline” for him.

Ramadan, Lent… how are religious fasts going?

Many religions around the world advocate periods of fasting, starting with the two most widespread religions: Christianity (2.4 billion people) with Lent and Islam (2 billion people) with Ramadan. Other religions also provide periods of fasting: for example, Hindus may follow different types of fasts, ranging from abstaining from one meal per day to fasting that only includes a small range of foods. In Judaism, there are also periods of fasting, including the fast of Yom Kippur, without food or drink, which takes place for a full day (fixed in October in 2024 and 2025).

The rules of fasting in Ramadan: how does Ramadan go?

Fasting in Ramadan consists of refrain from eating and drinking between dawn and sunset. It is therefore a form of intermittent fasting. However, there are no specific dietary restrictions, as it is possible to eat meals during the night and early in the morning. Fasting in Ramadan is obligatory for all healthy adult Muslims, once they reach puberty, with exceptions for pregnancy, breastfeeding, menstruation, children before puberty, and travelers.

Ramadan takes place for one month, during the ninth lunar month of the Muslim calendar. It therefore changes date every year. In 2024 and 2025, Lent and Ramadan occur at approximately the same times of year.

Lent among Christians

Lent begins on Ash Wednesday and lasts for 40 days before Easter. During the Lenten fast, Christians are invited to limit their food intake, but, in practice, in the Catholic religion the way of conducting this fast is left to the discretion of each individual. It is customary not to eat meat on Good Friday.

Fasting practiced by the Orthodox: the strictest fast among Christians

There are different approaches to fasting depending on denomination, with a restrictive food fasting pattern among Greek Orthodox, Eastern Orthodox, and Coptic Christians. Unlike Ramadan, this fast does not limit food intake during the day, it rather consists of eliminate intake of animal products and fats. It is therefore a form of “periodic vegetarian diet”.

The recommended fasting period for Orthodox Christians can last up to 180-200 days per year, with several fasting periods:

• the Nativity Fast, before Christmas in December;
• the period of Lent;
• the fast of the Assumption or Dormition, in the month of August.

Dietary restrictions vary from one period to another, and follow a specific schedule. These limitations concern meat, oil, eggs and dairy products. For example, during certain periods of Orthodox fasting, it is sometimes permissible to eat fish. The result is a dietary model that is close to the principles of the Mediterranean diet, rich in fruits, vegetables and legumes. Studies have suggested that Orthodox Christian fasting may be associated with a positive impact on lipid profile.

What are the benefits of fasting?

Intermittent fasting is associated with many health benefits: it helps you lose weight, reduce inflammation in the body, improve cardiovascular health and control your blood sugar. Regarding cardiovascular health, intermittent fasting can reduce blood pressure, oxidative stress and the risk of atherosclerosis (1).

To find out more, read our dedicated article: The benefits of intermittent fasting

The effects of religious fasts on cardiovascular health

Studies have shown that fasting in Ramadan can improve blood pressure, lipid profile, weight and overall cardiovascular risk factors. At the same time, as Orthodox fasting leads to a diet close to the Mediterranean diet, we can expect similar benefits.

Recently, a team from Aston University in Birmingham (United Kingdom) published a study on the effects of religious fasts on cardiovascular health (2). Their results show that these two approaches to fasting are associated with a reduction of cardiovascular riskbut for different reasons (3).

“Ramadan fasting was associated with a significant reduction in blood pressure and body weight, while Lenten fasting among Orthodox Christians was associated with a significant reduction in cholesterolexplains Duane Mellor, one of the authors of the study, on the site The Conversation. The drop in blood pressure in people who fast during Ramadan could be due to not eating or drinking during the day, which lowers insulin levels which can act on the sympathetic nervous system and reduce blood volume. Orthodox Christians who follow a plant-based fast may reduce their fat intake and increase their fiber intake compared to their usual diet, which could explain the association between their Lenten fast and lower cholesterol.”

However, some of these benefits may be negated by overconsumption of less healthy foods and drinks when breaking the fast.

Ramadan: frequently asked questions and tips for healthy fasting

To continue practicing your physical activities during the month of Ramadan, follow the advice of Dr Fabrice Kuhn, sports doctor, in this video:

Can I fast if I am sick and taking medication?

Overall, it is not recommended to fast if you have health problems. Seek medical advice. If you are taking medication, you may need to change your dosing times if they are timed with meals. Talk to your doctor or pharmacist.

Ramadan and diabetes: can we fast?

Diabetic patients may experience difficulties while fasting because strict and prolonged fasting can increase the risk of hypoglycemia and diabetic ketoacidosis. Muslim diabetic patients can fast during Ramadan, but with careful planning and adjustment of medications (4), insulin therapy can be continued during fasting if properly titrated to the patient’s needs, and blood glucose levels should be assessed regularly. If certain symptoms such as hypoglycemia, hyperglycemia, dehydration or acute illness appear, or if blood sugar levels become too high or too low, the fast must be broken.

Can you drink water during Ramadan?

No, Ramadan does not allow drinking during the day. You must therefore hydrate well at night, by drinking water and eating foods rich in water (melon, strawberries, watermelon, zucchini, etc.). During the day, if it is hot, dress lightly and avoid direct sunlight to limit the risk of dehydration.

To go further, read: How to fast

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