Associations between sedentary activities and overweight/obesity have been demonstrated in experimental and epidemiological studies; traditionally this has been assumed to involve the displacement of physical activity, promoting positive energy balance and weight gain. Increasingly, researchers are challenging the utility of this ‘energy balance approach’, proposing that sedentary activities may promote weight gain through metabolic perturbations. A three arm, prospective, randomised control trial was conducted in 72 overweight/obese adult males, divided into three equal groups: (i) watching TV; or playing (ii) a non-violent video game; or (iii) a violent video game. The 1-h intervention was followed by a 25-min rest period where a selection of sweet and savoury snacks/drinks was available ad libitum. Data on stress (heart rate, blood pressure, and visual analogue scale (VAS)) were collected throughout. Heart rate, systolic blood pressure, and stress measured by VAS were all significantly higher (p < 0.05) when playing video games (FIFA and COD groups combined) compared to watching TV. Ad libitum energy intake after playing video games was 173 kcal (p < 0.03) higher than controls, in association with a preference for sweet and fatty foods (p < 0.05). Furthermore, playing the violent video game (COD) was individually associated with stronger preference for sweet foods (p < 0.01). A 1-h session of playing video games in overweight/obese adult males is associated with a stress response, and increased calorie intake, which might arise through stress-induced cerebral metabolic perturbations. Furthermore, playing the violent video game may cause an enhanced cerebral metabolic perturbation, associated with preference for sweet foods.