Thank you for your question.
The local timings must be followed for the fasting. If you break your fast according to Mecca timings, your fast will be nullified and you will have to do both qada (make it up) and kaffarah (penalty which is to fast 60 days successively etc).
Although days are very long, the fasting does normally not cause any harm to you or to your health. But if it is proven (medically or based on one's own experience) that a person is unable to fast or to continue the fast because of extreme hunger, thirst or illness etc, then the solution is that this person can postpone the fasting to be performed at a later possible period.
Najeeb ur Rehman Naz