Postingestive inhibition of food intake by aspartame: importance of interval between aspartame administration and subsequent eating.

Aspartame administered in capsules (i.e., without tasting) 1 h before a meal significantly reduces the amount eaten in that meal. In the present study 36 young men and women were divided into 3 groups of 12 to receive aspartame (400 mg) or placebo (400 mg starch) on separate occasions either 5 min (Group A), 30 min (Group B) or 60 min (Group C) before beginning an ad lib test meal. Compared with placebo, aspartame reduced food intake in Group C (by 18.5%, p < 0.01), but did not reliably affect intake in Groups A or B. There were, in contrast, no significant effects of aspartame on premeal ratings of hunger, desire to eat or fullness for any of the groups. These results confirm a postingestive inhibitory action of aspartame on appetite, which may involve the amplification of the satiating effects of food. The lack of effect of aspartame administered at the shorter intervals before eating suggests a postgastric or even postabsorptive mechanism of action. This observation is also important in its implications for the possible therapeutic exploitation of the anorexic effect of capsulated aspartame.