People may joke about needing their coffee to function in the morning, but in all seriousness, caffeine is a drug. It’s most often consumed in coffee, tea, soft drinks and, in smaller doses, chocolate. While we seem to have a love affair with these foods, there’s been quite a bit of confusion and even controversy surrounding caffeine lately. Is it good or bad for us?

Research seems to say conflicting things about the effects of caffeine, so it helps to understand the pros and cons. Here are the basics of what you should know about caffeine and some surprising answers to these questions.


“Caffeine can improve physical performance in an endurance exercise like running, but the effect is less for short bursts of movement such as lifting weights or sprinting,” says Matthew Ganio, a professor of kinesiology at the University of Arkansas. Caffeine prompts the body to burn more fat stores instead of the limited stores of carbohydrate in our muscles. When the muscles run out of carbohydrate, you get tired. The benefit may be smaller in regular caffeine users.


When the pain comes on, the blood vessels in your brain widen; caffeine constricts them. It’s also a mild pain reliever.


Many experts believe that increased levels of cortisol lead to stronger cravings for fat and carbohydrates, and cause the body to store fat in the abdomen. (Abdominal fat carries with it greater health risks than other types of fat.) Also, if increased cortisol levels lead to stronger cravings for caffeine-laden foods, the body goes into a cycle that leads only to worse health. The good news, though, is that caffeine can speed up metabolism. Also, it can help the body break down fat about 30% more efficiently if consumed prior to exercise. (You must be exercising to get this benefit, though.) Additionally, caffeine can keep blood sugar levels elevated, leaving you feeling less hungry.


The March of Dimes recommends that women who are pregnant or trying to become pregnant consume no more than 200 mg of caffeine a day because the harmful effects of more than that on fertility and fetal health “cannot be ruled out.”

It helps your brain react

A caffeine buzz can really snap you out of a sleepy lull. In doses up to 300 milligrams, studies suggest it enhances attention, reaction time, and “vigilance,” meaning you’re able to stick with “lengthy, boring, or tedious tasks,” according to one review of caffeine’s effects.

Whether caffeine is a boon to higher-level mental tasks is less clear, researchers note. Its impact on problem solving and decision making, for example, “are often debated.”

Caffeine’s risk to bone health is minimal

Caffeine slightly reduces calcium absorption, studies suggest. Other studies link the caffeine and phosphorus in colas (but not other soft drinks) to bone loss.

As long as you’re getting enough calcium in your diet and you’re otherwise healthy, there’s no solid evidence that consuming up to 400 milligrams of caffeine will harm your bones. Studies to date have shown no significant fall or fracture risk, nor heightened risk of bone loss among healthy adults with adequate calcium intake.


In a study that followed more than 130,000 men and women for 30 years, drinking coffee (regular or decaf) didn’t increase the risk of cardiac arrhythmias, even among those with existing heart conditions.

Blood Pressure

While caffeine users experience a modest increase in blood pressure, long-term studies don’t show a clear link between coffee consumption and the development of hypertension, notes Rob van Dam of the National University of Singapore.

Parkinson’s Disease

In a study of more than 300,000 U.S. men and women, those who consumed at least 600 mg of caffeine a day (an eight-ounce cup of coffee has between 95 and 200 mg) were about 30 percent less likely to be diagnosed with Parkinson’s over the following ten years than those who consumed the least caffeine (less than 20 mg a day). Parkinson’s patients gradually lose the nerve cells that produce the neurotransmitter dopamine. Caffeine protects those nerve cells.