People who suffer from obesity hear all too often that it is their own fault. But the causes are complex. Obesity can lead to diabetes, cardiovascular diseases and other health problems. Stomach reduction surgery can be a godsend. Nutrition researchers at Wageningen University & Research (WUR) are working closely with hospitals to investigate the role of nutrition in this respect. How can vitamin deficiencies be prevented after surgery? Which foods, diets and lifestyles help prevent the patient from becoming overweight again?