Previous studies have shown that subjects who play video games are prone to consume larger quantities of food than subjects who are simply resting. This is believed to be due to the development of a stress response in the video games group, resulting in increased fuel metabolism. However, it was shown that the energy intake of the two groups showed no correlation with the subjects' appetite/hunger, which was identical in both groups.

The investigators propose to explore this issue further by comparing the effects of different types of video games on metabolism, using a randomized controlled trial. In this study, they will compare the stress levels, heart rate, blood pressure, appetite/mood, energy consumption, grip strength, memory and saliva cortisol, leptin and ghrelin levels of subjects playing (a) competitive and (b) problem-solving video games. Measurements will be taken preceding, during and after the 1 hour intervention. Following the intervention, participants will be offered savoury and sweet foods/drinks, which will allow us to assess their appetite preferences and caloric intake.

The investigators first aim is to determine whether there is a significant difference in stress levels, eating habits and energy metabolism in the two groups. Our second aim is to determine whether there is a difference in glucose distribution to the muscles and brain between the two groups.

The investigators study is designed to test experimentally whether different kinds of video game generate different types of metabolic response. The exposure comprises one-hour of video game playing, with 36 young men randomized to each group (ie 72 in total).

Prior to the exposure, they will collect baseline data on heart rate, blood pressure, anthropometry (weight, height, waist girth), grip strength and cognitive function (memory test), as well as appetite/mood by visual analogue scale (VAS). The investigators will also collect a baseline saliva sample to assess hormones associated with stress (cortisol) or satiety (leptin, ghrelin). The subject will arrive after and overnight fast and will be given a standardised breakfast. After these baseline data are collected, the randomization envelope will be opened and the subject assigned to his group.

Heart rate will be monitored continuously during the study. At 20 and 40 minutes during the intervention, as well as when it ceases at 60 minutes, the investigators will collect further data on blood pressure and appetite/mood by VAS. At 60 minutes, the investigators will repeat measurement of memory and grip strength, and collect a second saliva sample.

For 20 minutes after the end of the intervention, the subject will be allowed to rest, reading magazines, and will be able to select from a range of snack foods (savoury, sweet, fruit), and drinks (sweetened beverages, water). Consumption of calories will be calculated. At the end of this period, final measurements of blood pressure and VAS will be collected, and the subject will depart.

Inclusion Criteria:

• Healthy adult males with BMI <25 kg/m2

Exclusion Criteria:

• smoking
• a significant weight change (>3kg) within the previous three months
• any psychiatric disorder
• uncontrolled hypertension
• coronary heart disease
• heart failure
• central/peripheral arteriopathies
• excessive alcohol consumption (<21 units/week).