The reason that Muslims fast (aside from being commanded to) is to gain something called “taqwa” which is like, fear of God, awareness of God, piety, etc. It makes a person more aware of God.
The fast is abstaining from all food (not just meals) and all drinks (even water) for all the daylight hours. No snacks, no gum, no cigarettes, no water breaks, etc. And also abstaining from sexual intercourse during the day. Are those the “rules” you’re talking about which take away from the meaning? That’s what makes it a fast, that the person is deprived of things which the body demands, and forces the person to control their body.
What makes Ramadan special though isn’t the fasting–it’s all the extra prayers (like 1-2 hours every night before bed, another hour before dawn) and reading Qur’an etc.
Not all Muslims have to fast though… children, pregnant women, people who are sick or traveling, they are exempt from the fast–so it is not to cause undue hardship.