Here we tested the hypothesis that compared with the normal-weight subjects, normal-weight subjects submitted to a rigorous and continuous monitoring of body weight as karate athletes are characterized by a increase of attentional cortical responses to the enlargement of faces or food. Electroencephalographic data were recorded in 15 karate athletes and 15 non-athletes during an "oddball" paradigm. The subjects were given frequent (70%) and rare (30%) stimuli depicting faces (FACE), food (FOOD), and landscapes (CONTROL), and clicked the mouse after the rare stimuli. These stimuli depicted the same frequent stimuli graphically dilated by 25% along the horizontal axis. Bioelectrical impedance indexed subjects' body fat percentage. Cortical attentional responses were probed by the difference between positive event-related potentials peaking around 400–500 ms post-stimulus for the rare minus frequent stimuli (P300). LORETA estimated P300 sources. The results showed that in the FACE condition, the amplitude of medial parietal P300 sources (Brodmann area 5) was higher in the karate athletes than normal-weight subjects. These results disclose that parietal attentional processes to face size are increased in karate athletes. The present study motivates future research evaluating the effects of cognitive rehabilitation to control the body weight in athletes.