This is a question that many people ask, and it's one of the main reasons why Burn Lab Pro has become so popular. The fact remains: even though stimulants can be useful for fat burning (particularly in some contexts), they also have side effects such as increased heart rate or insomnia if taken at night time - which makes them unsuitable to use every day long-term with no breaks! In contrast, with a stim-free fat burner like Burn Lab Pro, you won't find caffeine anywhere on its ingredients list; instead, there are healthier substances like Capsimax cayenne pepper extract, which provides stimulant-like benefits minus the side effects!