This is not a question that can really be answered with a specific number. The answer will vary from person to person and it would be best to consult a medical professional to get a solid answer for your individual situation. Some people would benefit by weight loss, others might just need to adjust their habits in order to improve their abilities and quality of life. Generally speaking, weight loss will not matter as much as eating healthy and getting regular exercise. Both of these will have an impact on quality of life.