However, to my knowledge, no studies evaluate the effectiveness of multi-ingredient pre-workout supplements taken after a meal or on an empty stomach. So this doesn’t necessarily mean pre-workout is more effective when fasted.
What are the side effects of taking pre-workout on an empty stomach?
Taking pre-workout on an empty stomach could result in headaches, jitters, nausea, or upset stomach. However, a recent study suggests that these side effects generally are insignificant and occur in a small percentage of people4.
Related: Does Pre-Workout Cause Acne?
Can pre-workout damage your stomach?
While taking pre-workout can cause digestive discomfort, there are no indications that supplementation results in stomach damage. But, of course, any supplement’s short-term and long-term side effects depend on the formulation and dosage, so always check the label.
Does pre-workout on empty stomach make you poop?
Taking a pre-workout supplement can cause a sudden bowel movement. And this result may be more pronounced when you take pre-workout on an empty stomach.
However, not everyone will need to go number two because it depends on several factors, including the amounts of specific ingredients in the pre-workout supplement.
Related: 7 Pre-Workout Ingredients That Can Make You Poop