What is your eminence’s opinion regarding a person whose work is strenuous and it is difficult for him to fast, is it permissible for him to break the fast?
It is my opinion in this matter that for him to break his fast due to work is unlawful, and it is not permissible. If it is not possible for him to reconcile his work with fasting, then he should take off from work during Ramadan, so that it is easy for him to fast in Ramadan. The fast of Ramadan is one of the pillars of Islaam and it is not possible to forsake it.
Shaykh Muhammad bin Saalih al-`Uthaymeen
Islamic Verdicts on The Pillars of Islaam, vol.2, page.630