Many techniques are met in the literature, trying to investigate the effect of TV watching hours on BMI. However, we haven’t traced any empirical study with co-integration analysis, as it is applied here. With this in mind, we present in this paper the proper methodology, based on the co-integration analysis for a detailed justification of the effect of TV viewing hours together with some minor changes in life style of participants on BMI. Apart from finding and testing an acceptable co-integration relation, we further formulated an error correction model to determine the coefficient of adjustment. All findings, which are fully justified, are presented in details in the relevant sections. It should be pointed out, that we haven’t met this type of analysis in the relevant literature.