The fastest driver of fat loss is a sustained energy deficit. You create it by eating fewer calories, burning more calories, or both. Starving can drop scale weight quickly, but it increases the risk of muscle loss and metabolic slowdown. A more effective approach is higher-protein nutrition, increasing daily steps, and doing resistance training 2–4 times per week to preserve muscle. Cardio helps, but the “fastest” method is the system you can actually follow for weeks. Poor sleep and chronic stress can increase appetite and reduce adherence, so sleep and stress control are often the hidden drivers of successful fat loss.