Volume and variety: relative effects on food intake.

Volume has been shown to be an important direct control of food intake, since larger volumes of food consumed prior to a meal can inhibit subsequent intake. Variety of food is known to stimulate food intake. The present study was designed to examine the relative effects of manipulating the volume of a soup preload in the context of providing either a single or a variety of sandwich fillings. Thirty participants (15 females; 15 males) attended the laboratory on 4 occasions to receive a low (f=240 ml, 3.6 kJ/g; m=300 ml, 3.6 kJ/g) or high (f=480 ml, 1.8 kJ/g; m=600 ml, 1.8 kJ/g) volume tomato soup preload 30 min before a sandwich lunch with either single or a variety of fillings. Overall, subjects reported significant differences in hunger and fullness as a function of volume manipulations but the satiety quotient (SQ: change in ratings divided by weight of soup) calculated just before lunch indicated a smaller SQ for high than for the low volume soup. Therefore, although subjective ratings were influenced by volume this was not sufficient to affect intake at lunch. Variety (2344+/-200 kJ) increased food intake at lunch compared to the single filling condition (2062+/-171 kJ), an enhancement by variety of 14%. In conclusion, lowering energy density and increasing volume by adding water failed to reduce intake at lunch. Clearly volume effects on intake rely both on amount consumed and energy density. As predicted, variety stimulated food intake and this occurred across volume conditions.