What Fasting Does -- and Doesn't Do -- to Running Performance
The most useful data point on this isn't theoretical -- it comes from a study of elite male distance runners tracked across a full Ramadan. Despite meaningful drops in daily calorie, carbohydrate, and water intake during the fasting month, their time to exhaustion and maximum running speed actually improved, with peak oxygen uptake unchanged[3]. That's a genuinely counterintuitive finding, and it comes with an important asterisk: the runners in that study also cut their training volume by roughly 48% during Ramadan, so the gain reflects reduced training stress meeting a still-adapted body, not proof that fasting itself boosts fitness.
The broader sports-nutrition literature backs up the underlying point -- with properly managed nutrition, hydration, training load, and sleep, most runners can get through Ramadan with little meaningful performance loss[1][2]. The operative phrase is 'properly managed.' Runners who try to train exactly as they would outside Ramadan, at the same volume and intensity, on the same fueling schedule, are the ones who tend to run into trouble -- not runners who deliberately scale back and shift when and how they train.
Choosing a Training Window: Suhoor, Iftar, or the Hours Between
Sports-nutrition guidance built specifically around Ramadan generally points to three usable training windows: early morning shortly after the pre-dawn Suhoor meal, a lighter session just before Iftar, or -- often rated the most favorable -- two to three hours after Iftar, once a runner has had time to properly rehydrate and refuel before training and still has the rest of the evening to recover afterward[1]. Each comes with a tradeoff: a Suhoor-adjacent run happens on a full stomach but leaves a runner fasted and thirsty for the rest of the day, while a pre-Iftar run is the most physically depleted window but rewards a runner with immediate recovery food right afterward.
For runners in a region where race culture is already built around pre-dawn starts, an early-morning Suhoor-window run isn't an unfamiliar shift -- the timing is close to a normal race-day wake-up. The difference during Ramadan is that the run happens without the usual pre-run coffee or breakfast, so hydration the night before matters more than usual, and dietetic guidance specifically recommends moving harder, higher-intensity sessions closer to Iftar when possible, precisely because that's when fueling and rehydration can happen immediately afterward rather than hours later[2].
Hydration and Fueling Strategy Across the Non-Fasting Hours
The consistent number across sports-dietetics guidance is roughly 2.5 to 3 liters of fluid spread across Suhoor, Iftar, and the evening in between -- taken gradually in regular sips rather than in one large sitting, which the body absorbs and retains far less efficiently[1][2]. Electrolyte-rich foods and drinks, not just plain water, matter here too, since a full day without any fluid or sodium intake is a meaningfully different challenge than simply drinking less over a normal day.
Suhoor works best built around slow-digesting carbohydrates and a solid protein source -- oats, wholegrains, eggs, yogurt -- that release energy gradually across the fasting hours rather than spiking and crashing early[1][2]. Iftar traditionally opens with dates and water, which is also good practical fueling advice: quick natural sugar to end the fast, followed by a balanced meal with lean protein, vegetables, and carbohydrate to handle both the day's accumulated deficit and, on training days, genuine recovery.
When a Race Falls During Ramadan
The most common approach among runners who face this is to treat the month as maintenance rather than peak performance -- adjusting goal pace expectations downward for a race that lands during Ramadan rather than expecting a personal best, and leaning on the guidance above to protect fitness rather than chase it. Evening races, which are less common in this region's early-morning race culture but do exist, are logistically the easier case, since a runner can fuel and hydrate at Iftar beforehand in something closer to a normal pre-race routine.
For a race that falls during fasting hours, the practical strategy is to maximize hydration and glycogen stores at Suhoor and in the days leading into race day, and to treat the effort itself more conservatively than usual. This is also a genuinely personal decision that depends on faith practice and health -- guidance consistently notes that people managing conditions like diabetes should seek a medical exemption from fasting rather than push through it for a race[1][2], and that principle scales down to anyone whose health status makes fasting and hard training a risky combination. None of this is a substitute for a runner's own religious guidance or a doctor's advice on their specific situation.