Why you need bcaas in your workout now! The Best Supplements to Fight Fatigue. When youve ruled out any medical issues and developed positive habits but are still struggling with fatigue, it may be time to turn to supplementation. We took a look at the most common causes of fatigue—sleep, stress, and exercise—and put together a list of simple, supplemental fixes to address each one. Check out the list to eliminate fatigue and get back in the game.