You probably don't want to fill it to the top, especially with hard/dense items, because it is not an" industrial strength" machine. That's not a negative, that's just the purpose it was designed to serve. However - for example- it easily can do 2 cups of zucchini squash cut into 1 inch cubes with no trouble. We've done onions, garlic, etc. with no trouble. I believe the real key is to cut your items into smaller cubes.