What does energy drinks work for?

Energy Shots
For a lower-calorie, less filling alternative to energy drinks, consumers are turning to energy shots, the fastest-growing category in the energy-beverage market. Sales jumped from $67 million in 2008 to $165 million in 2010, according to Mintel. Marketers at Red Bull say that the size of the company's Energy Shot is a plus for consumers, who can stick it in a purse or back pocket. "Distance runners or cyclists might be tempted to use energy shots as a quick, portable fix," says Nancy Clark, RD, author of Nancy Clark's Sports Nutrition Guidebook. Toss back a two-ounce bottle shot, such as 5-Hour Energy, and you'll get roughly the same amount of caffeine, vitamins, and supplements that are in the average energy drink, minus the calories and pick-me-up from sugar. "An energy shot is sort of a misnomer, because there is no energy, calorically speaking, in it," Clark says. "It's really a stimulant drink."
But your body gradually develops a tolerance to caffeine's effect, and you become desensitized to its buzz. "If you've ever noticed how one cup of coffee used to get you going in the morning, and now it takes two or three, it's the same thing with energy shots," Ganio says. "The body builds a resistance to caffeine over time, requiring you to consume more and more to get that same lift."
One of caffeine's secrets is that it doesn't just stimulate your brain; it keeps it from detecting fatigue. "Every function of the body requires the molecule ATP, adenosine-5-triphosphate, to work," Ganio explains. "As the ATP is used and broken down, it creates the by-product adenosine. Adenosine binds to receptors in the brain, resulting in feelings of lethargy. Caffeine binds to these same receptors, however, blocking the adenosine from attaching, so you're left feeling awake."
Sports Drinks
Sports drinks, such as Gatorade and Powerade, were designed primarily for two reasons: to help athletes stay hydrated and to provide them with energy. "When the availability of carbohydrates gets too low, the body starts converting fat stores or, in extreme conditions, amino acids from the muscles into energy," says Melissa Tippet, an exercise scientist at the Gatorade Sports Science Institute in Barrington, Illinois. "However, this process is too slow to support intense exercise." Enter sports drinks, which provide easy access to carbs.
Designed specifically to be used during physical activity, sports drinks tend to have less sugar than energy drinks. "On average an energy drink can have upward of 100 calories per eight-ounce serving; a sports drink has 50 to 80," Clark says. Whether you need the fuel a sports drink provides depends on how hard and long you're working out. "If you've eaten prior to exercising, you won't need additional carbs until you've been working out for 60 to 90 minutes," Clark says. "But if you work out first thing in the morning, sipping a sports beverage will raise blood sugar levels and give you more energy to get through it."
Because sports drinks are typically formulated with a more diverse blend of carbs than energy drinks are, your muscles can maximize their energy-sustaining potential. "Each type of sugar, whether it's fructose, sucrose, or glucose, has specific transporters in the body that move it between the intestines, blood, and muscle," Tippet says. "If you have too much of one type of sugar at a time, it can max out its transporter and just sit in the stomach or intestines."
Wondering about the new, low-cal options? Although Gatorade's new G Series Fit 02 Perform and others replace fluids and electrolytes, they don't give the body much fuel, because the sugars have been replaced with substitutes. If the flavors of the lab-created beverages don't do it for you, you can make your own sports drinks by diluting fruit juice with water in equal parts, Clark advises.
Power Packs
Commonly ranging from 90 to 120 calories a serving, energy gels and gummies promise to prep the body for exercise and help you work out longer. "They are like dehydrated sports drinks," Clark says, noting that you should drink 16 ounces of water with every 100-calorie gel to ensure that you stay hydrated. "We recommend that people doing an endurance sport, like running or biking, consume a gel 15 minutes before exercise and every 45 minutes for the duration of the workout," says Brent Mann, director of quality for Gu Energy Labs in Berkeley, California. "Taking in carbohydrates at these intervals prevents your body from dipping into its glycogen stores, its last resort for energy." (Most experts stress that products such as Gu Energy Gel and PowerBar Energy Gel are geared to endurance sports, much as sports drinks are; the average exerciser doesn't need additional calories if she's eaten within 90 minutes of a treadmill session.)
In addition to sugar, most energy gels contain small amounts of sodium and potassium to help replenish electrolytes; some also contain caffeine. "Caffeine has been shown to lower perceived exertion during exercise and lessen muscle pain," Ganio says. "The debate is this: Studies show you need a lot -- six milligrams of caffeine for every 2.2 pounds of body weight -- to achieve this effect." That means that a 140-pound woman would need 381.8 milligrams of the stimulant, roughly four cups of coffee. So while some gels in the Gu line contain up to 35 milligrams of caffeine, Gatorade's G Series 01 Prime liquid formula contains none. "Caffeine isn't in any of our products," Tippet says. "Everyone responds differently to caffeine; it's effective for some people but for others may cause negative side effects, like jitteriness and heart palpitations."
One perk of these products, some industry experts say, is that they require little work from your stomach. "During intense exercise, blood that is normally in your gut to aid in digestion is redirected to the heart and working muscles," so you want something that goes down easy, Mann says. "That's where these gels can help."
So which of these engine revvers is really right for you? In moderation, any of them should give you the lift you're looking for without dangerous side effects. The bottom line, experts say, is to first make sure your diet offers the nutrients your body needs. "If they're eating the right foods, many women may not feel it's necessary to supplement at all," Zeratsky says. The best energy, it turns out, comes straight from nature.