Adding a significant amount of fiber to your diet can have positive effects in the success of your weight loss program. In addition to preventing painful constipation, it also improves the body's ability to balance itself through regular bowel movements. Over time, this will have a favorable effect on your overall metabolic function, which leads to weight loss.
If you are a pizza lover it is okay to eat a slice of two here and there, but you can still cut calories and fat by doing a couple of things. Buy pizza by the slice, so you do not end up eating the whole thing. Also, opt for veggie toppings instead of meats, and do not add any extra cheese.