My recipes often call for cups, half cups, quarter cups, pinches, handfuls...that's because I don't like to weigh everything and I honestly think that cooking is a creative process.
If you've ever been on a diet, you can probably make a tablespoon of peanut butter look like the leaning tower of Pizza, and a handful...well, a handful can be a lot.
Why we want to "cheat ourselves" into eating more that we think is a topic of another post here, but in my cooking class this Saturday we decided to finally end the handful discussion. So we put walnuts, raisins and chopped dried apricots in a certain 5.2ft, 130 lb female and after removing what everyone thought was a handful, in the actual palm of her hand, we had these neat piles, half the size of what everyone thought a handful was.
Of course, if you are a guy, things change by about 1/3, or you can just curl your fingers to make a "mini handful", if you are really watching calories. So measure, cook, eat and feel great, both about the recipe and your shape.