Out of the energy-rich nutrients the reduction in the dietary intake of fats entails an increase in carbohydrate intake. The various carbohydrates owing to differences in their chemical and physical properties influence differentially satiety, and plasma levels of glucose and lipids. The present survey gives a short account on the carbohydrates occurring in the nutrients, deals with their effects on metabolism, and discusses the relationship between carbohydrate intake and obesity on the basis of recent research findings. At present, it appears that there is no convincing evidence available, which would suggest that the action by simple sugars and by complex carbohydrates is different on glucose tolerance, plasma lipid profile, and on the development of obesity.