Every year, nearly two billion people fast from dawn to sunset for a month. For a long time science paid little attention to the practice; since intermittent fasting became a major research field, studies have multiplied. What do they actually say? And above all, how do you live your Ramadan well, from suhoor to iftar? An honest overview, with no miracle promises.
“O you who have believed, fasting has been decreed upon you as it was decreed upon those before you, that you may become righteous.” — Quran 2:183
First, put things in their place
Ramadan fasting is not a diet. The Quran assigns it an explicit purpose: taqwa, God-consciousness. Hunger is not the goal, it is the means: it trains self-mastery, recalls the condition of those who are hungry without choosing it, and frees time and attention for prayer and the Quran. If science happens to find beneficial effects along the way, all the better; but a Muslim does not fast for their mitochondria.
A useful clarification: Ramadan fasting is a dry fast (no food, no water) whose length is dictated by the sun, which distinguishes it from the intermittent fasting protocols studied in laboratories (16 to 20 hour windows, water allowed). Results from one do not automatically transfer to the other.
What science observes during the fast
- The metabolic switch. Around 10 to 12 hours after the last meal, the liver's glycogen stores run down and the body progressively switches to burning fat, producing ketone bodies. A day of Ramadan fasting reaches precisely that switching zone. It's also why late afternoon is often the roughest stretch: the body is mid-transition.
- Autophagy, with caution. The 2016 Nobel Prize in Medicine, awarded to Yoshinori Ohsumi, recognised the discovery of the mechanisms of autophagy: the cell's recycling of its worn-out components, stimulated notably by nutrient deprivation. It's a fascinating lead, but honesty requires saying that most of the evidence comes from animal studies or prolonged fasts, and directly measuring autophagy in humans remains difficult. We can welcome it without turning Ramadan into a “detox cure” that science has not validated in those terms.
- Health markers. Meta-analyses of Ramadan observe on average a slight weight loss and modest improvements in some markers (blood lipids, glycemia), often reversible after the month. The decisive variable is not the fast itself but what is eaten at iftar: the month can lighten you or weigh you down.
- The real challenge: sleep. Ramadan studies converge on a surprising point: the month's main physiological difficulty is not hunger but reduced sleep (night meals, tarawih, suhoor). Daytime fatigue blamed on fasting often comes, in reality, from shortened nights. Protecting your sleep is therefore the first strategy of a successful Ramadan.
Suhoor: the most important meal of the month
The Prophet ﷺ said: “Take suhoor, for in suhoor there is blessing” (Bukhari, Muslim), and recommended delaying it close to dawn. Chrononutrition applauds: a late meal shortens the real deprivation window and delivers energy closest to the day ahead. In practice:
- Complex carbohydrates (oats, wholegrain bread, legumes) that release energy slowly, rather than fast sugars that crash mid-morning;
- Protein and good fats (eggs, yogurt, nuts), the most satiating nutrients;
- Water first, going easy on tea and coffee whose diuretic effect wastes part of the hydration;
- Never skip it, even reduced to dates and a large glass of water: it is both the sunnah and physiological common sense.
Iftar: break, pray, then eat
The sunnah of breaking the fast with dates and water is remarkably intelligent: after a day of fasting, dates provide immediately available carbohydrates to restore blood sugar, and water starts rehydration. Pausing next (the Maghrib prayer) before the real meal gives the satiety signal, which takes about twenty minutes to reach the brain, time to arrive. The result: you eat better and less than by diving straight at the table.
The hadith of thirds (“a third for food, a third for drink, a third for breath”, Tirmidhi) remains the month's best nutrition advice: heavy, overloaded tables are the main cause of the sluggishness, reflux and evening fatigue of Ramadan. Between iftar and bedtime, drink regularly in small amounts rather than all at once.
The body, sport, and long days
- Physical activity: the most comfortable slot is late afternoon, one to two hours before iftar (the effort ends just as you can drink), or after the evening meal for more intense sessions.
- Napping: a 15 to 20 minute qaylula in the early afternoon repays part of the lost night sleep and softens the alertness dip.
- Listen to your body: headaches in the first days (often caffeine withdrawal: taper coffee during the preceding week), dizziness or faintness are signals to take seriously.
Who should not fast
Islam provided exemptions before modern medicine: the sick, the traveller, the pregnant or nursing woman, and the frail elderly are not required to fast, with compensation or make-up days depending on the case. If you live with diabetes, a chronic illness or daily medication, talk to your doctor before the month: adapting or postponing your fast on medical advice is not a failing, it is applying the text. “Allah intends for you ease and does not intend for you hardship” (Quran 2:185).
The heart of the month remains the heart
At the end of this overview, let's keep the hierarchy clear: science describes mechanisms, it does not found the act. Billions of fasting people do not rise before dawn to optimise their metabolism, but to answer a divine prescription, train their soul, and share a month of generosity and community. May the discoveries about fasting nourish gratitude rather than pride: the wisdom was there before the laboratories.
Ramadan in Deenius
Deenius shows suhoor and iftar times computed locally for your location, sends reminders at the right moment and works fully offline. The Ramadan tab follows your month day by day, with no account, no ads, and no data ever leaving your iPhone.