The weight-increasing effect of fructose in hypercaloric trials may have been attributable to excess energy rather than fructose itself .
Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories .
Free fructose at high doses that provided excess calories modestly increased body weight , an effect that may be due to the extra calories rather than the fructose .
BACKGROUND The contribution of fructose consumption in Western diets to overweight and obesity in population s remains uncertain .
PURPOSE To review the effects of fructose on body weight in controlled feeding trials .
Macronutrient disposal during controlled overfeeding with glucose, fructose, sucrose, or fat in lean and obese women.
BACKGROUND Previous short-term studies ( < or = 6 h ) showed differences in energy expenditure ( EE ) and macronutrient oxidation in response to overfeeding with different types of dietary carbohydrate . This finding could have implication s for obesity . OBJECTIVE We used 96-h continuous whole-body calorimetry in 8 lean and 5 obese women to assess metabolic disposal ( energy dissipation and glycogen or fat storage ) of a controlled excess of dietary energy supplied as different carbohydrate sources or as fat . DESIGN Five dietary treatments were applied in r and om order : energy balance ( control ) and overfeeding by 50 % of energy requirements with fat ( O(fat ) ) or predominantly with glucose , fructose , or sucrose ( O(cho ) ) .  Macronutrient oxidation rates were assessed from nonprotein gaseous exchanges . Net macronutrient balances were calculated as cumulative differences between intake and oxidation . RESULTS Increased EE in response to overfeeding dissipated 7.9 % of the energy excess with a variation in EE of < 1.7 % across overfeeding treatments ( NS ) . EE during the O(fat ) treatment significantly exceeded that during the control treatment in the lean but not in the obese women . There were no significant differences between lean and obese women in macronutrient oxidation or balances , so data were pooled . O(cho ) induced glycogen storage on day 1 ( approximately 100 g ) but thereafter progressively stimulated carbohydrate oxidation so that balance was reached on days 3 and 4 . Fat oxidation was proportionately suppressed . Of the excess carbohydrate , 74 % was oxidized ; there were no significant differences between the various O(cho ) treatments . O(fat ) stimulated fat oxidation by 18 % and suppressed carbohydrate oxidation . On average , 12 % of the excess energy was stored as glycogen and 88 % as fat ; there was no significant difference between overfeeding treatments . CONCLUSION There was no significant difference in fat balance during controlled overfeeding with fat , fructose , glucose , or sucrose
The weight-increasing effect of fructose in hypercaloric trials may have been attributable to excess energy rather than fructose itself .
Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories .
Free fructose at high doses that provided excess calories modestly increased body weight , an effect that may be due to the extra calories rather than the fructose .
BACKGROUND The contribution of fructose consumption in Western diets to overweight and obesity in population s remains uncertain .
PURPOSE To review the effects of fructose on body weight in controlled feeding trials .