It is generally known that no days are equivalent to the days of Ramadan except the days of another Ramadan. At the same time, all days of Ramadan are originally fast-days, so that one can never make up for the missed fast-days of Ramadan during another Ramadan. That is why Abu Hurairah, may Allah be pleased with him, said: “Whoever did not observe fast for one day of Ramadan for no legal excuse or on account of a disease can never make it up later.” (Narrated on the authority of Abu Hurairah, by Al-Tirmidhi, Abu Dawud, An- Nasa’i, Ibn Majah, Ibn Khuzaimah, and Al-Bayhaqi, and the quoted version is At-Tirmidhi’s.) However, one of its narrators is weak.
It was also narrated, on the authority of Abu Hurairah, that a man did not observe fast in Ramadan deliberately with no legal excuses. Hence, Abu Hurairah said: “Even if he fasts for a whole year, he will still not have made up for that day.” It was also narrated, on the authority of Ibn Masu`d, that the Prophet, peace and blessings be upon him, said: “If anyone breaks his fast one day in Ramadan without a concession granted to him by Allah, a perpetual fast will not atone for it.” “Whoever breaks his or her fast for one day of Ramadan deliberately without any legal concession, then even if he observed fast for life, it would not compensate for that day.”Abu Bakr and `Ali Ibn Abi Talib were also reported to have said words with the same meaning.
In this regard, Dr. Muzammil Siddiqi, former President of the Islamic Society of North America, states:
“Fasting during the month of Ramadan is an obligation fard upon every adult Muslim who is not sick or on a journey. It is a sin to miss the fasts of Ramadan without any excuse. The Prophet (peace and blessings be upon him) said, “Whoever broke even one fast of Ramadan without an excuse or sickness, even if he fasted the whole life after that it will not compensate what he missed.” (At-Tirmidhi)
(As far as the first question is concerned), I suggest that the person who breaks a fasting day of Ramadan without excuse should repent sincerely and ask Allah’s forgiveness. Allah has promised that if anyone repents sincerely, Allah accepts his repentance and forgives him.
the person who does this should also try to make up for the missed days. He should calculate how many days of Ramadan he missed. Make up for those days by fasting one day for each day that one missed. If one cannot then give the kaffarah, which is a day’s meals or its value to be given to a needy person. We estimate about seven to ten dollars per day for each day’s fast.
Thus, by doing these deeds, one may not be able to compensate totally for the missed days of Ramadan, but at least one will express his sincere repentance and effort to fulfill the Commands of Allah.”
Based on the above, we can conclude that intentional breaking for fasting in the day of Ramadan by eating or drinking is a very serious sin, and the one who did that should sincerely repent to Allah and make up for the missed day(s) he/she has missed as this is the way how to make up for intentional breaking of fasting for obligatory fasting days of Ramadan.