Fitness coach Dan Go, with 18 years of experience, suggests a protein-sparing modified fast as the fastest way to burn fat while preserving muscle. This medically supervised approach involves a very low-calorie (800-1000 kcal), high-protein diet, with minimal carbs and fats, paired with strength training. Go emphasizes this intense method is for short-term use, typically one to two weeks, to achieve rapid fat loss without sacrificing muscle mass.