What does obesity mean? One of the people's health markers is the nutritional steady-state, the mean ponderal equilibrium. The normal weight means the longest life expectancy assuring body weight, from all points of view. The body weight increasing means adipose tissue accumulation and the onset of obesity. Obesity quantification could be made by BMI (body mass index)--normal range 22-24 kg/m2- waist to hip ratio--normal range 0.8-0.9--and abdominal perimeter--normal range up to 80 cm. Why should we do obesity prevention? Because obesity means a high risk factor for cardio-vascular disease, cancer, bone diseases, general mortality. By 10 kg weight loss, real benefits are achieved: left ventricle hypertrophy reduction, decreasing of cardio-vascular risk, pulmonary function improve, reducing of atherosclerotic symptoms by 91%, of arterial pressure by 10-20 mmHg, of diabetes mortality by 30%, cancer by 40% and general mortality by 20%. In our country, 53% of population is overweight and obese, predominantly urban population. Obesity costs are high: about 4-8% of health budget are spent for screening, diagnosis and obesity management, including economical losses. When should we do obesity prevention? Primary care physicians must control all health indexes. If the patient passes over normal ranges of body weight, we should take account and intervene efficiently, by specific and non-specific therapeutic methods. How could we do obesity prevention? General care physicians and specialists could prevent efficiently this disease by taking apart obesity causes and risk factors: genetics, life-style, drug intake, smoking, professional and endocrine factors. Primary and secondary care physicians have to screen high risk persons, to analyze professional, familial and social conditions, to appreciate educational and economical status. All these realize an integral obesity management, together with the psychologist and the sociologist. Secondary prevention means obesity treatment, in order to prevent complications and, in the same time, to maintain normal body weight after ponderal excess loss. Obesity prevention is an important and complex social problem to debate. We have to mobilize political and economical factors, food industry, education. Obesity control means protection against one of the most aggressive health risk factors.