it would depend on what brand
No. With or without chocolate, granola bars are high in sugar and fat, and low in nearly all the nutrients of real, live food. They are marginally better than cookies, or a sweet breakfast cereal, but not so different.
If you have a generally healthy diet, a granola bar once or twice a week won't do too much damage, but if you're looking for staples to be the basis of a healthy diet, forget them.
For a quick snack, eat fresh fruits or "finger" vegetables like carrots, celery, cherry tomatoes, etc., and maybe a little bit of 100% whole-grain crackers (but not so much of that until you recover from the digestive difficulties that you've mentioned elsewhere).can you lose weight by eating granola bars and drinking vitman what