That's because your burning your fats.Do your sit-ups daily, after a few days you will never feel any pain.
Sit-ups aren't necessary, and aren't encouraged anymore. If you can do crunches and sit-ups hurt, don't do sit-ups. Why get complicated about it? There are a million different ab exercises out there, so there's not need to do any particular one to work that area.
Also, I have talked to a doctor before about it, it was back in 7th grade when I was being diagnosed with diabetes. He said my muscles just didn't connect right when I was little because of the hernia, but he said it doesn't feel like i still have one or that it was dangerous.
It actually hurts after only a couple sit-ups, in the muscles right below my ribcage. It isn't a stabbing pain or anything, but it does hurt in a more than uncomfortable way. I just feel normal fatigue when I do crunches, so I don't know why sit-ups are different except that maybe they work the muscles more where I use to have a hernia.
Well, you're in luck! Nobody recommends sit-ups anymore because they are very hard on the lower back. When you say they hurt, do you mean they are hard to do, or they hurt you somewhere on your body?
Talk to a professional fitness instructor. also ask a doctor about your condition.
i think now is the right time to see your doctor.