There is controversy concerning the role of sugar in the epidemics of obesity and metabolic syndrome. There is less controversy concerning the effects of fructose on components of metabolic syndrome; consumption of fructose has been shown to increase visceral adipose deposition and de novo lipogenesis (DNL), produce dyslipidemia, and decrease insulin sensitivity in older, overweight/obese subjects. This review examines the potential mechanisms of these effects of fructose and considers whether these mechanisms are relevant to the effects of consuming sucrose or high-fructose corn syrup. Evidence demonstrating that the commonly consumed sugars increase visceral adipose deposition, DNL, and insulin insensitivity is limited or inconclusive. Evidence that sugar consumption promotes development of an unfavorable lipid profile is strong and suggests that the upper added sugar consumption limit of 25% of energy or less, suggested in the Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans 2010, may merit re-evaluation.