Energy drinks are caffeine-and-sugar cocktails that come in 8-ounce cans. Caffeine boosts cognitive performance, and glucose (the brain's main source of fuel) gives an added jolt. Many of these drinks also include a rain forest fruit called guarana, which contains still more caffeine. Down a can and it's hard not to feel rocket fueled—but some people also experience anxiety, insomnia, headaches, and increased heart rate and blood pressure from all that caffeine. And the sugar can total 31 g, as much as a can of soda packs. By comparison, a standard cup of coffee with 2 teaspoons of sugar has about 8 g and will fortify your body with disease-fighting antioxidants in addition to caffeine.
Suck It Up
Think of energy gels as concentrated, Jell-O-like versions of sports drinks. Designed for endurance athletes, they come in plastic pouches that can easily be ripped open and squeezed down the hatch for a superquick fix of carbs, along with electrolytes to replace those lost through sweat. The sugars deliver instant energy because the body can process them so quickly. "They're almost predigested," says Julie Upton, RD, coauthor of Energy to Burn. "There's no chewing required because endurance athletes can't eat when they're exercising at such high intensities." If you're running a marathon, an energy gel might help you finish. But if you just want an afternoon lift, there are more satisfying options.
Energy bars are easy to buy and stash in your purse for a pick-me-up on the go. They purport to provide lasting energy, give you the nutrients you need, and power you through a tough workout. Some of them actually are good for you—especially those that contain whole grains, nuts, or fruit, such as Larabar and Bear Naked Grain-ola. The problem is, many are little better than candy bars, with nearly half their calories coming from various forms of sugar. While these may give you a 15-minute mood boost, you'll get a sugar crash soon after and will have consumed 200 or more calories. So choose carefully or make one yourself.
Gulp & Go
Your friends the food marketers thought it would be fun to compress a full-size energy drink into a 2-ounce can. Women often gravitate to energy shots because they have fewer calories and easily slip into a purse. Manufacturers claim the energy boost acts faster and lasts longer, but there's no proof, says Liz Applegate, PhD, director of sports nutrition at the University of California, Davis. In fact, because the cans are petite (and contain artificial sweeteners instead of sugar, which companies say prevents a crash), you might be tempted to drink more of them, making it easier to OD on caffeine. And the taste...well, the label may say lime, but your mouth will know better—metallic and bitter is more like it.
Jelly Belly Sport Beans, Gu Chomps, and other energy chews are similar to gels but, well, chewable. They're great for endurance athletes who have "bonked" or "hit a wall" and need immediate fuel to complete a race, especially if they can't stomach the taste of gels. But some of these, experts say, are basically gumdrops with added vitamins and minerals. Assuming you get your nutrients from real food, you don't need these, so the only "benefit" is sugar. In the middle of an Ironman? Go ahead and pop a few into your mouth. Otherwise, think of energy jelly beans and chews as candy. You wouldn't expect sustained energy from a bag of Skittles, so why think these will be any different?
Yep, even energy drinks have gone green. Steaz, Sambazon, and Guayaki offer organic beverages that promise to make you alert and focused—naturally. In addition to sugar and various fruit extracts, all include yerba mate. The leaves of this tropical tree contain caffeine and two similar stimulants, theophylline and theobromine, and have been used by South Americans to combat fatigue. Lab studies also rate yerba mate high in antioxidants. The downside: The sugar contents are similar to those of other energy drinks—and organic ones cost more and are harder to find. Still, for liquid lightning, they're your best bet among the canned beverages.