Ramadan 2021: What happens to your body when you fast? "Fasting has positive effects on mental health too," said Dr Salama Mohamed Al Hosani. Fasting during the holy month of Ramadan boosts the immune system which in turn protects the body against infections, a Abu Dhabi medical expert said. “As we consider the influence of Covid-19 on Ramadan this year, we can also consider the effects of fasting on keeping fit and safe, as well as how it affects the immune system,” said Dr Salama Mohamed Al Hosani, specialist physician, health operations management, headquarter division, Ambulatory Healthcare Services Company (SEHA). “When we begin to fast, the body initially breaks down a number of immune-fighting white blood cells. It instinctively knows to start saving energy and one way it does this is by killing off old or damaged immune system cells. It adjusts and triggers the regeneration of new cells, therefore increasing the number of immune-boosting cells,” she added.