The prevalence of obesity and overweight is increasing globally and forms a huge public health problem. On the other hand, the prevalence of malnutrition or undernutrition is substantial, especially in nursing homes or in the elderly at home. Primary care and public health are separate disciplines. But in the field of nutrition and other lifestyle-related interventions, there are many direct and indirect interfaces for over- as well as undernutrition. The Dutch College of General Practitioners (NHG) published the Practice Guideline Obesity in adults and children to lead GPs in this process and to bridge the gap with public health. The same applies for the recently published National Primary Care Cooperation Agreement Undernutrition on the collaboration of primary care workers to enhance awareness and early intervention in case of nutritional impairment. This article goes into the background as well as the content of these two NHG products and the implications for daily practice. An attempt is made to connect primary care and public health in this matter. Particularly in the case of obesity, a close relationship with public health is of vital importance.