In the 1990s, excessive fat consumption was commonly believed to be the main cause of obesity. High sugar consumption was often considered to be innocuous and possibly protective against obesity by displacing dietary fat.
A decade later, the American Heart Association linked intake of added sugars to weight gain and recommended substantial decreases in consumption to a daily maximum of 100 kcal for women and 150 kcal for men.
Some experts now argue that sugar comprises the single most important cause of the worldwide epidemics of obesity and diabetes, primarily through the effects of fructose at prevailing levels of consumption.
This Viewpoint examines the physiological effects of common sugars and argues against a narrow public health focus on fructose.