Caffeine is the most widely used stimulant drug in the world, usually ingested in the form of coffee, tea, soft-drinks, and of course energy drinks.
Caffeine is absorbed by the stomach and intestine, and peak blood levels occur about 45 - 60 minutes after ingestion. Once in the blood stream, caffeine causes a number of responses in the body. Caffeine is well known for it’s stimulant effects on the brain, but there are a number of other effects that occur.
Blood pressure, pulse rate, and stomach acid production are increased, fat stores are broken down, and fatty acids are released into the blood stream. These effects can last from a few hours to as long as 12, but within 4 days or so of regular use, the body develops tolerance to many of the effects of caffeine. For example, although caffeine increases blood pressure and pulse in a first time user, a regular user will not experience any significant change.
Because caffeine increases the production of stomach acid it may worsen ulcer symptoms, cause heartburn, or give you that sick feeling in your gut. Insomnia, poor sleep, and anxiety are also side effects of caffeine. Regular evening use of caffeine may, over time, deprive the body of proper sleep, resulting in lack of energy and fatigue.
Abrupt discontinuation of caffeine in a regular user may trigger caffeine withdrawal symptoms. The most common symptoms are headache and fatigue. The headache may begin as soon as 18 hours following the last dose of caffeine. Differences in metabolism, diet, and frequency of caffeine use are some of the factors that can determine how an individual will react to caffeine.
Although caffeine does not appear to significantly alter water balance or body temperature, dehydration is a potential concern because caffeine is a mild diuretic.
Caffeine like anything else should only be used in moderation. If you rely on it on a daily basis to “get through the day” odds are you’re barely reaping any real benefit from it, or have to consistently increase your intake. Your best bet is to use it sparingly. Take a few days off now and again from it. You never want your body to become reliant on any substance to function. Proper diet and exercise will always trump any sort of stimulant whether you are using it for energy, weight loss, or both.