Coffee drinking has existed for centuries but despite numerous studies into its advantages and disadvantages to health, there are still different takes on what exactly qualifies as too much coffee.

Dietitian Susie Burrell writes in a post on the Health Insurance Fund of Australia that each person's caffeine tolerance actually varies, hence one person might not be as sensitive to the ill-effects of coffee drinking compared to another person. Burrell determined that there's a general rule to knowing if you've drunk too much coffee. She also enumerated some of the warning signs that indicate an over consumption of caffeine.

One way to gauge if a person has too much coffee is if they rely on more cups to get through the rest of the day, as the presence of caffeine stimulates the body's blood flow and heart rate that brings more energy. Burrell, however, said that this stimulation wears off immediately, hence a person might feel more fatigued after an hour of drinking coffee.

Drinking cup after cup of coffee could also affect a person's ability to sleep, so people who are more sensitive to the bad effects of coffee could suffer from sleep deprivation. Too much coffee could also cause sugar cravings and overeating, thus the dietitian suggests that it would be healthier to drink water instead of coffee if these side effects crop up.

"A general rule of thumb is aiming to keep your total intake of caffeine below 300mg each day, which equates to one or two coffees and three or four cups of tea," Burrell said.

A new study published in the JACC Clinical Electrophysiology journal also recommended consuming just 300mg of coffee a day. The study authors said that three cups of coffee a day is best for lowering the risk of arrhythmias or abnormal or irregular heartbeats after surveying 228,465 coffee drinkers.

The experts, however, advised that people with heart conditions must first discuss their coffee drinking habits with their doctors. They also discouraged the consumption of energy drinks to replace coffee.