Frequent Running During Fasting: Beware of Dehydration and Hypoglycaemia Risks

Running whilst fasting can still be performed, but this activity carries several health risks that warrant careful attention, particularly if undertaken with extended duration or high intensity.

Dr. Risky Dwi Rahayu, M.Gizi, Sp.K.O, a Sports Medicine Specialist at Pondok Indah Hospital, stated that the primary risks of running whilst fasting relate to fluid and energy depletion in the body.

“The risks of long-distance running whilst fasting are dehydration and hypoglycaemia,” said Dr. Risky in an interview with Kompas.com on Wednesday (25/2/2026).

According to her, both conditions can manifest if physical activity is undertaken without proper timing and nutritional planning.

During fasting, the body receives no fluid intake over an extended period, increasing the risk of fluid loss. Running activity that triggers perspiration can accelerate this fluid loss. This condition can cause the body to feel weak, dizzy, and reduce exercise performance.

If not properly anticipated, dehydration can also affect the body’s overall balance.

During fasting, the body’s energy reserves come from food consumed at pre-dawn meals (sahur). Physical activities such as running can accelerate the consumption of these energy reserves.

If energy reserves are insufficient, blood sugar levels can drop, triggering symptoms such as weakness, dizziness, or difficulty concentrating.

Exercising after breaking the fast can be a viable option as the body has restored its energy and fluid levels. During this period, exercise intensity can also be conducted at higher levels compared to whilst still fasting.