Starting the day with a steaming cup of coffee or tea is a habit for many, with caffeine often seen as a mood booster or even a daily necessity. In the UK, people collectively drink around 95 million cups of coffee daily, according to the British Coffee Association.

But what exactly happens to our body when we consume caffeine?

A report highlights that the effects of caffeine vary depending on factors such as the amount consumed and individual differences, including genetics and metabolism. Thomas Sanders, a professor of nutrition and dietetics at King’s College London, explained that the impact of caffeine differs significantly from person to person, with potential gender-related variations in how the body metabolizes it.

Psychological and Physical Effects of Caffeine

The mood-lifting feeling experienced immediately after drinking coffee is often a placebo effect rather than an instant biological change. According to Professor Sanders, caffeine takes approximately 20 minutes to be absorbed into the bloodstream, which is when physical changes, such as an increased heart rate, begin. For those feeling lethargic, this can provide a slight boost in energy, which is why morning coffee is a ritual for many.

At the 20-minute mark, caffeine can also trigger a fleeting "rush of euphoria," which contributes to the feel-good sensation that coffee lovers associate with their first cup. Concentration levels tend to peak about an hour after consumption, though individual metabolism rates may alter this timeline.

Caffeine's Impact on the Body

Caffeine’s diuretic effect often leads to increased urination about 30 minutes after consumption. This effect can be more pronounced in individuals with bladder or prostate issues, as noted by Professor Sanders. After 60 to 90 minutes, caffeine stimulates the bowel, making it more active. Studies show that caffeine increases colon activity by 60% compared to water and 23% compared to decaf coffee.

Caffeine Crash

Eventually, caffeine leads to a slump, commonly referred to as the caffeine crash. For instance, coffee consumed at 8am may result in a crash by 11am, prompting many to reach for another cup. By noon, caffeine typically leaves the system, reinforcing a cycle of dependence. Professor Sanders explained that over time, the brain’s receptors adapt to regular caffeine intake, creating an expectation for another dose to maintain energy levels.