SHAFAQNA – The Grand Ayatollah Sistani answered a question about exams and fasting.
Question: Can a person not fast in order to take an important exam and pass it with good marks?
The Grand Ayatollah Sistani: Continuing with studies is not an acceptable excuse for not fasting. But if the supposition is that leaving behind the studies will damage or cause difficulties to a level which normally cannot be tolerated, and continuing with studies is not possible whilst fasting; by having the intention to fast, can eat and drink to the necessary amount, but do not eat or drink to become full, and then can compensate by fasting for that day later on, and Kaffarah is not (Wajib) for such a person. Of course, the person can travel before noon to a distance of 22 kilometres outside the town, and break his fast in there, because he is a traveller and then can return, and he is no longer fasting, and only must compensate for that day by fasting later on.
Source: PERSIAN SHAFAQNA