In this closing perspective, the author exposes why targeting a single nutrient like sugar is in his opinion unlikely to be efficient in preventing obesity and metabolic diseases. He defends the proposal that the concept of fructose toxicity is based on major misconceptions of nutritional physiology. He specifically proposes that (1) sugar being a non-essential nutrient does not obligatorily imply that it has no beneficial effect; (2) alterations of blood triglyceride concentration and hepatic glucose production within the normal range may merely reflect adaptations to a fructose-rich diet rather than early markers of diseases; (3) overfeeding is a normal physiological response to exposure to an energy-dense, palatable nutrient rather than the consequence of 'leptin resistance'; (4) we may presently overemphasize the role of biological regulations and of gene-related heredity when assessing the effects of fructose in particular, and the determinants of obesity in general.