When you need a little recharging, drinks like Monster Energy and Rockstar can give you a boost. But when it comes to which one works better, it's a tossup. While studies have been conducted on whether these types of drinks work, none has been done comparing which one works best.
What Gives You Energy
Both Monster and Rockstar energy drinks contain a number of ingredients purported to give you energy, including carnitine, guarana and panax ginseng. But other than guarana, which is a source of caffeine, there is no evidence to support that these ingredients work as claimed, according to the Department of Nutrition at the University of California, Davis. The boost you feel after drinking a can of Monster or Rockstar is likely due to its caffeine content -- and maybe a little from the sugar.
Caffeine is a nervous system stimulant. Both Monster and Rockstar energy drinks contain the same amount of caffeine per serving, which is 80 milligrams in 8 ounces. For comparison, an 8-ounce cup of coffee contains 130 to 240 milligrams of caffeine depending on the brew.
The caffeine content in the drinks does not take into account the amount of caffeine provided by the guarana, however.
For health and safety, you should not consume more than 400 milligrams of caffeine a day, or more than 300 milligrams if you're pregnant.
A Look at Carbs
When it comes to energy, carbs are your body's first choice. Monster and Rockstar contain similar amounts of carbs. An 8-ounce serving of Monster has 27 grams of carbs and 27 grams of sugar, while the same serving of Rockstar has 30 grams of carbs and 30 grams of sugar. While the carb content between the two drinks is slightly different, it's likely not enough to make much of a difference in your energy levels.
It's important to note that the diet versions of these drinks contain very few carb grams to none at all.
Energy Drinks and Energy
The University of California notes that the evidence to support the energy-boosting power of energy drinks is slim. A 2014 study published in the Journal of the International Society of Sports Nutrition tested the effects of Monster Energy Drink on exercise capacity in a group of active men and women. The study found that the energy drink did not enhance their exercise performance.