Place the chicken breasts and chopped onions into the bottom of a slow cooker.
Min a medium bowl, whisk together the barbecue sauce, honey, Worcestershire sauce, and olive oil. Pour over the chicken.
Cover and cook for 6 hours on LOW or 3 hours on HIGH.
When there are 30 minutes left of cooking time, uncover and shred the chicken using 2 forks right in the slow cooker. Then mix the chicken back into the sauce. Cover and continue cooking for 30 minutes.
Serve warm on buns with your favorite toppings.
Notes
Nutritional information is for chicken and sauce only, and accounts for all the sauce being used.