The “best fat burner” is usually not a supplement—it is a set of habits: consistent movement, adequate protein, portion control, and quality sleep. Among supplements, caffeine and green tea catechins have the most research support, but effects are modest and individual-dependent. In real life, the best fat burner is a plan you can follow, train with, and track. If you choose a supplement, evaluate the ingredient list, dosing, and stimulant tolerance, and be cautious if you have hypertension, palpitations, or anxiety. “Best” should mean safe, sustainable, and repeatable—not just fast.