Hal Larsen (JACK BLACK) and his friend Mauricio Wilson (JASON ALEXANDER) are two average looking guys who are extremely picky when it comes to how women should look. Of course, their shallowness means they're not particularly successful with the ladies, which is why Hal's across-the-hall neighbor, Jill (SUSAN WARD), has decided to dump him after just one date.
After that and not getting the promotion he expected, Hal's a bit depressed, but finds himself unexpectedly stuck in an elevator with motivational guru Tony Robbins (TONY ROBBINS). Upon hearing Hal's idea of an ideal woman, Tony decides to deprogram, or essentially brainwash Hal into seeing only a person's inner beauty, rather than judging them on their outward appearance.
Accordingly, when Hal meets various women he believes to be knockouts who aren't traditional beauties, Mauricio can't believe that his friend has suddenly dropped his standards and expectations and tries to inform him of such. Yet, Hal simply thinks his friend is crazy, and that's especially true when Hal meets and falls for Rosemary Shanahan (GWYNETH PALTROW), an extremely obese woman whom he sees as model-like thin.
While Rosemary initially is suspicious and/or disbelieving of Hal's compliments about her appearance, his behavior soon wins over her and her parents (JOE VITERELLI & JILL FITZGERALD), a point that doesn't escape Hal's co-workers since Mr. Shanahan runs the company where they work.
As Hal climbs the corporate ladder, and he and Rosemary hang out by themselves as well as with friends such as Walt (RENE KIRBY), a man suffering from spina bifida who gets around on all fours, things seem to be going great for them. That is, until Mauricio decides he must take matters into his own hands to return Hal back to the way he used to be.