Through hard work, I have been able to shed 28 pounds since Christmas, but am having trouble in my stomach area. I have heard conflicting reports. Some people say that I should not do any sort of sit-up until I have lost a little more weight.
Some people say a little toning is good.
As for your question, I believe everyone that can safely perform crunches should do so. I consider the muscles of the abdomen one of the most important muscle groups that you can train. In fact, before I train someone with other strength training exercises, I make sure their abdomen is good and strong. It's your abdomen that is instrumental in stabilizing your entire body so that you can not only safely and effectively lift weights, but you are also able perform all types of activity at higher levels. Unfortunately, many people do crunches solely to lose fat in their abdominal area.