The study is investigating the metabolic response to playing competitive non-violent and competitive violent video games. The primary hypothesis is that the metabolic response in the violent game group will differ from the other two groups, due to activation of the stress response. The investigators are using an experimental approach, whereby 72 young men are randomised to one of three groups: watching television (TV), playing the non-violent video game 'FIFA2013', or playing the violent video game 'Call of Duty'. Participants arrive fasted, and are given a standardised breakfast. After measurements of weight, height and waist girth, they then are assigned to one of the three groups. Baseline blood pressure, heart rate and appetite/mood data are collected, along with a saliva sample for measurement of the 'stress' hormone, cortisol. The investigators will collect these data again at 4 time-points during the one hour game-playing session. At the end of the study, the allow the participants half an hour of rest, during which they can choose from a variety of sweet or savoury snacks. The investigators will compare the data from the three groups, to test whether changes in blood pressure, heart rate and salivary cortisol, as well as snack consumption, are greater in the group playing the violent game.

Our study is investigating the metabolic response to playing competitive non-violent and competitive violent video games. Our primary hypothesis is that the metabolic response in the violent game group will differ from the other two groups, due to activation of the stress response.

We are using an experimental approach, whereby 72 young men are randomised to one of three groups: watching TV, playing the non-violent video game 'FIFA2013', or playing the violent video game 'Call of Duty'. All participants must already have some experience playing the two games, so that whichever group they are assigned to, they can comply with the protocol.

Participants arrive after an overnight fast, and are given a standardised breakfast (a muffin, approx 300 kcal, and a glass of water). After measurements of weight, height and waist girth, they then are assigned to one of the three groups, and allowed to familiarise themselves with the games console or TV. Baseline data on blood pressure (in triplicate, Accutor digital monitor), heart rate (Polar monitor) and appetite/mood (visual analogue scale) are collected, along with a saliva sample for measurement of the 'stress' hormone, cortisol, as well as satiety hormones sich as leptin and ghrelin. We will collect these data again at 4 time-points during the one hour game-playing session, by pausing the game or TV for 4 minutes at 15, 30, 45 and 60 minutes after the session starts.

At the end of the study, we allow the participants half an hour of rest, during which they can choose from a variety of sweet or savoury snacks or fruit, and several drinks.

We will compare the data from the three groups, to test whether changes in blood pressure, heart rate, appetite/mood and salivary hormones, as well as snack consumption, are greater in the group playing the violent game.

Inclusion Criteria:

• BMI >25 kg/m2

Exclusion Criteria:

• smoker
• weight change >3 kg in the previous three months
• psychiatric disorder
• uncontrolled hypertension
• coronary heart disease, heart failure and central or peripheral arteriopathies
• alcohol consumption > 21 units/week.