Specially formulated with 100 mg of caffeine, including green tea and green coffee extracts Each great tasting drink is also packed with 5 g of micronised amino acids, including BCAAs Delicious, sugar free and just 30 calories per serving! Optimum Nutrition's Essential Amino Energy delivers caffeine to help increase alertness and focus throughout your day, as well as essential amino acids. Mix up Essential Amino Energy any time you're looking to improve mental focus and alertness. It's ideal in the morning, for pre-workout priming, or as an afternoon booster.