Fasting during Ramadan changes how your body uses energy.

Ramadan fasting involves abstaining from food and drink from dawn until sunset and typically shifts the body from using glucose to burning fat and producing ketones; studies cited report short-term reductions in weight, inflammation and some blood pressure measures.

Ramadan begins this week and many Muslims will fast from dawn until sunset. The practice is primarily spiritual, but researchers and a dietitian describe common physical effects. Intermittent fasting of this type prompts the body to change which fuels it uses. Several recent studies and expert comments are cited to explain likely short-term outcomes and common early challenges. Known effects: - After roughly eight to 12 hours without food, the body shifts from using stored glucose to burning fat and producing ketones as an alternative fuel. - Blood sugar tends to fall and insulin production declines during fasting, which accompanies the metabolic switch. - Early days of fasting can bring tiredness, increased hunger, headaches and changes to sleep patterns linked to hormone shifts such as melatonin and cortisol. - The article notes hydration and food choices matter during the non-fasting window and mentions that caffeine can act as a diuretic. - Small studies and reviews cited include an Indonesian study of 137 students reporting weight and body fat loss, a 2021 paper noting some reductions in blood pressure, and reviews reporting lowered markers of inflammation such as cytokines. Summary: The described pattern of Ramadan-style fasting produces a metabolic shift that can lead to short-term reductions in weight, some measures of inflammation and blood pressure, while also causing dehydration risk and sleep disruption for some people. The reports and studies cited focus mainly on healthy adults and note that outcomes may differ for those with chronic health conditions. Undetermined at this time.