Energy and Caffeine

You see the commercials every day: energy shots, drinks, and supplements are touted on the airwaves as the cure-all solution for low energy and poor concentration. They claim to enhance everything from mental alertness to increased performance and boosted metabolism. But what do they put in these products and do they really work?

It turns out that the jolt of energy promised is based on two main ingredients: sugar and caffeine. Energy drink companies are quick to highlight the added B-vitamins and other nutrients that are thrown into the mix – but these vitamins and nutrients will only affect your energy and metabolism if you have a nutrient deficiency; which, thanks in part to the fortification of foods in the United States, most Americans do not. On the other hand, the main ingredient of caffeine is a known central nervous system stimulant, and can therefore increase feelings of alertness and decrease the perception of effort. This effect can be traced to a compound that prepares the body for sleep, called adenosine. Adenosine is shut out of the brain in the presence of caffeine, as caffeine “hogs” the brain’s receptors that usually pick up adenosine. When caffeine is picked up by the brain, adrenaline is released, which ultimately increases the body’s perception of having more energy. Numerous studies suggest that caffeine can also improve athletic performance and endurance with as little as 2 cups of coffee one hour prior to exercise. However, every individual exhibits a different response to caffeine and may experience varying degrees of stimulation, or lack thereof.

Due to these physiological effects on the body, caffeine is considered a drug – albeit a naturally occurring one – and has been classified as a controlled substance by the National Collegiate Association of Athletics (NCAA). Until 2004, caffeine was even banned by the International Olympic Committee (IOC) and World Anti-Doping Agency. There is little evidence to support that caffeine use results in the physical and social consequences associated with serious drugs of abuse, but if caffeine intake is abruptly stopped or altered, sensitive individuals may experience headaches, drowsiness, irritability, and/or restlessness. These symptoms typically last for a short time-period of 2-3 days and can be avoided by gradually reducing caffeine consumption over several days.

In moderation, most people will not experience detrimental effects to the body from consuming the amount of caffeine in the average energy drink or energy shot. However, too much caffeine, which can stem from consuming just a few of these drinks, can produce unwelcome side effects such as anxiety, jitteriness, rapid heartbeat, gastrointestinal distress, insomnia, dehydration, and even decreased energy. Excess caffeine from energy drinks can be potentially dangerous in sports, especially in combination with alcohol and other stimulants. Side effects can also occur from the overconsumption of coffee, therefore, moderate caffeine consumption is recommended at 200-300 milligrams, or the equivalent of 2-3 cups of coffee and 3-4 cups of black tea.

If you have low energy and/or reduced concentration, consuming caffeine is not the ideal way to compensate. Rather, it is a temporary solution to lack of sleep and an imbalanced diet. Instead, the Academy of Nutrition and Dietetics recommends limiting screen time, setting and enforcing a regular bedtime, engaging in calming activities before bedtime, and following a well-balanced nutrition plan that includes plenty of water. You can also exercise or eat several smaller meals throughout the day rather than three larger ones. Finally, if you feel you are getting too much caffeine in your diet, the Academy recommends mixing half decaf and half regular coffee together, or substituting coffee with decaffeinated and herbal teas.

Thank you M.M., UTHSCSA Dietetic Intern


Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Am Diet Assoc. 2009;109:509-527.

Ellen Coleman, RD, Back to the Grind: The Return of Caffeine as an Ergogenic Aid
Today’s Dietitian. Vol. 11 No. 3 P. 8

Elizabeth Lee and Kathleen Zelman, RD: Energy Shots Review: Do They Work? Are They Safe?

Academy of Nutrition and Dietetics: Running Low on Energy? Catch Those Zzz’s

Academy of Nutrition and Dietetics: How Much Caffeine is Too Much?

How Do Energy Drinks Work?

Caffeine Fuels Most Energy Drinks

International Food Information Council Foundation: Everything You Need to Know About Caffeine

Sports dietitian Nancy Clark, M.S., R.D: The facts about caffeine and athletic performance