Hypertrophy is influenced by personal aesthetic preferences, but maintaining sufficient muscle mass is crucial for health. The Fat-Free Mass Index (FFMI) serves as a key indicator, with target scores of 20 for men and 18 for women. Scores below 17 for men and 15 for women indicate significant physiological risks due to insufficient muscle. Knowing your body weight, fat percentage, and height can help calculate your FFMI and assess your muscle health.