General practitioners (GP's) presence is homogeneously distributed in the Lombardy territory. GP's are easy accessible by people so they could play a key role in the prevention of overweight and obesity. In this study GP's included in everyday medical activity a primary prevention strategy regarding nutrition and lifestyle. The goal was to maintain a constant BMI for one and a half year for at least 50% of the patients (stable means without progression within BMI's range). During the same time another endpoint was to decrease from 1 to 3 units the BMI in overweight patients in half of the observed population. Subjects were randomly recruited during routinely ambulatory activity, without a specific BMI based selection. Diet quality was assessed with a food frequency questionnaire regarding "protective foods" as vegetables, fruits and legumes. Some "basic" information about nutrition and lifestyle where then provided through explanation of issues printed on A4 page brochure. Percentage BMI's range variation before and after the intervention show a stability in the observed population, with an increase 0,3% for normal weight males and 0,9% for females. BMI was constant in 72,2% of the subjects considering a 1 unit variation and in 92,2% considering 3 units variation. Within subjects who varied 1 unit (27,7%) more subjects decreased rather than gained weight (16% vs 11,7%); within subjects who varied 3 units (7.8%), 4,5% decreased and 3,3 increased their BMI. GP's demonstrate to have an efficient role in weight gain control with a simple and regular prevention strategy towards healthy lifestyles and simple nutritional tips. It is important for patients to comprehend the importance the doctor give to the overweight and obesity problem, apart from the medical issue considered during the visit. GP's have a key role for healthy life-style change programs among their patients. These results provide new arguments about the opportunity to invest public resources towards population (managed in collaboration with GP's coordinated by a public health department such as NU), rather than towards a single patient. The project management was supervised by the Nutrition Unit (NU) of the public heath system SIAN (ASL di Brescia).