Latest Ask a Coach question comes from reader Pat regarding the efficacy of low calorie “energy” drinks:

Question: I recently saw some people taking a low calorie energy drink/shot like 5-hour Energy before a half marathon. Is there any science behind those high B vitamin drinks? By definition a calorie is a unit of energy, so if those drinks have little to no calories, then they can’t have much energy, right? Are they tricking our bodies into feeling more energetic?

Run SMART Coach Alicia Shay:

Hi Pat!
You are right, the 5-hour Energy drinks do not provide the form of energy that you need to sustain endurance activity. The reason for consuming sports drinks and gels is because they contain calories in the form of carbohydrates. During longer races these carbohydrates ensure that you do not run out of readily available glycogen (or glucose) that your body uses for energy to sustain exercise.

Drinks like 5-hour Energy are mostly comprised of large doses of caffeine, other stimulants and B vitamins. For most people caffeine does help improve performance but there is not a single clinical study that proves that the claimed large doses of caffeine, stimulants and B vitamins in 5-hour Energy further enhance athletic performance. In fact, for many people, the amount of stimulants in 5-hour Energy could be detrimental to optimal performance.

The most important fueling practice for longer races and workouts is supplying your body with adequate amounts of glucose (gels, drinks, candy, chomps, etc.). If your body responds well to caffeine then it is OK to also have some caffeine before or during the race. However, it is best to consume caffeine through a cup of coffee, tea or gels. Anything around 2-3 mg of caffeine per kilogram of body weight has been shown to improve endurance performance. 5-hour energy does not reveal exactly how much caffeine and other stimulants is in each bottle. So I would advise that you steer clear of any product that is not well researched and also does not list the specific amounts of ingredients in the bottle.

Also, too many stimulants combined with low blood sugar levels and a high heart rate while racing could be a recipe for disaster. And you’re right, it can ‘trick’ your body into thinking it has more energy and reserve than it really does.
I hope this helps!