The body mass index (BMI) is from about two centuries one of the main indicators of human health and is used in this sense in almost every country in the world. The purpose of this research is to analyze this indicator, based on the Gaussian distribution (or normal curve) in the time period 1994-2005, in order to provide a point estimate of the Italians in the condition of being overweight, according to the classification given by WHO. The report also provides forecasts to 2020 on the extent of BMI for overweight people, in order to assess the effects on the health of not only Italians, but also for the possible effects on the national health system.