Research has found that getting excessively engrossed or addicted to social networking services such as facebook etc can actually lead to obesity.
The consequences are much more harmful than what we think it is. People who are addicted to the computer will spend their days sitting in front of the computer; the time and energy which could be otherwise spent moving around turn into fats and a sluggish metabolism in the long run.
A combination of obesity and metabolic syndrome eventually results in a cluster of conditions that includes increased blood pressure, high blood sugar, excess body fat around the waist and abnormal cholesterol levels.
This actually applies to everyone as we seem to spend large a part of our days sitting down, be it at work or in school. It is thus necessary for us to make good use of our free time working out instead of spending even our free time sitting down and in front of the computer!