Does a healthy diet help to prolong life? A healthy diet certainly helps to prolong life. On the other hand, think about unhealthy diet. I'm sure it will reduce life span, such as overeating, increase gastrointestinal peristalsis and slow down gastrointestinal function. I could have worked for 50 years, so overeating may only work for 40 years. So are other body parts. Therefore, a healthy diet helps to prolong life.