Thank you for your question about skin tightening options following a substantial weight loss of 50 kg. I understand the challenges you're facing with loose, sagging skin, and your desire for improvement in its appearance. Skin Elasticity Factors: Your skin's ability to retract post-weight loss is influenced by genetics, age, smoking history, radiation damage (like sun exposure), and the extent of weight loss. After such a significant weight loss, the skin's elasticity is often compromised, making it difficult for the skin to constrict or contract back to its former state naturally. Limitations of Non-Surgical Modalities: While skin treatments like J-plasma or RENUVION show promise in non-weight loss patients, their effectiveness is considerably limited in cases of major weight loss, particularly over 50 kg. Surgical vs. Non-Surgical Approaches: Unfortunately, no non-surgical methods can adequately tighten excessively loose skin following a 50 kg weight loss. Building Muscle Mass: One non-surgical approach you might consider is building muscle mass. Through weight lifting and exercise, you can increase muscle volume beneath the skin, which may slightly improve skin tightness. However, this approach has its limitations and may not fully address significant skin laxity. Considering the extent of your weight loss, a consultation with a plastic surgeon might be beneficial to explore surgical options for skin tightening. They can provide you with information tailored to your specific situation. I hope this information helps you understand the available options and their limitations. Wishing you the best of luck in your journey to achieve your desired results. Sincerely, Dr. Katzen