I've done quite a lot of work on cultural and religious issues and patients in the NHS, and I can assure you that there are exemptions for people who need to take regular medicine in order to stay well - the intention of Ramadan is not to make people ill, it's to instil self-discipline. Many may choose not to take the exemption, though, and still choose to fast. Those who are ill are not obliged to fast, groups like menstruating women can defer their fast until a later date... etc.
The period of time this year is a lot longer than 12 hours - the chaplain at the Games in Edinburgh this morning said that the fast starts in Scotland now at 03.15am and lasts till 10.30pm
NJ mentioned the bus driver - my late BIL used to work in Bangladesh and saw men working on building sites in the summer Ramadans, who were crazed with lack of water during long hot days.
If I had to fast, I could manage the food, but not the water....
Going back to the OP - AOG, Health Promotion units across the country issue shedloads of cautionary leaflets for the general population about food, alcohol, sunburn, drinking over Christmas - etc - you must have missed them....