Asking in the name of Jesus means to ask as He would ask, according with His plans and purposes.
When we do, we can know that God hears us, that our desires will be fulfilled and we will receive whatever we ask.
Jesus' earthly ministry reveals His purpose and will regarding sin, sickness and disease. He never turned away anyone who came to Him for forgiveness or healing. It tells us that He forgave and healed all who came to Him and asked. So when we ask for forgiveness and need healing in our bodies we can ask in His name and be confident that we will receive.