the problem with dennis and the fat boy of the title and be exactly that . what be his problem . he a loser and a scumbag and utterly unlikeable and and at no point in the film do he become a nice and likable and or sympathetic character . so it be very hard to root for someone this self involve . at no point be he ever nasty or pathetic in a funny way and he just a jerk . and no matter how many emotional scene be ram in and it have be five year since he leave his pregnant fiancée at the alter . five year of see her every day . how be it only now that he want to do anything about it . and it doesn not matter if he do . it be five year . it too late . luckily for him and the people he want to win back and the dull libby and their duller son jake and be so flat and the audience can not care about them either . especially jake . and the lazy demonising of libby new love whit be obvious and convenient so dennis can worm his way back in to libby affection after five year of be the most detestable and unreliable jerk she could hope to meet . so and run fat boy run isn not funny . there be a couple of joke that possibly could have work a part of a sitcom and but never in a one off film and but just to make it clear and this isn not funny . the serious scene be even bad and fall horribly and uncomfortably flat and and the painful drag out of a heart warm end be not heart warm . there be no character development or motivation and so basically there be nothing here that be need to make a film . dire .