The actual, but not labelled, fat content of a soup preload alters short-term appetite in healthy men Martin R. Yeomans*, Suvi Lartamo, Emily L. Procter, Michelle D. Lee, Richard W. Gray Laboratory of Experimental Psychology, University of Sussex, Brighton BN1 9QG, UK Received 5 December 2000; received in revised form 22 January 2001; accepted 28 March 2001 Abstract The effects of the actual and labelled fat content of a soup preload on appetite at a test meal 30 min later were assessed in 16 healthy men. Each participant ate lunch on four occasions, combining two levels of fat energy (Low, 265 kJ or High, 1510 kJ) and two types of label (Low-fat or High-fat), presented as fictitious soup brand names. Preliminary work established that the Low-fat labels produced an expectation of reduced fat content and lower anticipated hedonic ratings, whereas the High-fat labels generated expectations of a high-fat content and above average hedonic ratings. These expectancies were confirmed in the main experiment, with the soups labelled as high fat rated as both more pleasant and creamy than those labelled low-fat, independent of actual fat content. However, intake at the test meal was unaffected by the preload label, but instead reflected the actual fat (hence, energy) content of the soup, with significantly lower food intake after the high-fat soup regardless of the food label. Rated hunger was lower, and fullness higher, at the start of the meal after the high-fat preloads regardless of how they were labelled, while the pattern of appetite change during the test meal was unaffected by preload. These results suggest that realistic food labels can modify the immediate experience of a consumed food, but do not alter appetite 30 min later in healthy men. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Hunger; Satiety; Preload; Fat; Food label; Human 1. Introduction Studies that have examined voluntary food intake after disguised preloads, which vary in energy or nutrient content, have had mixed results (see Ref. [1]). The most consistent results have come from studies using preloads based on carbohydrate (e.g., Refs. [2–9]), where there is good evidence for subsequent reductions in food intake. Some studies report an exact reduction in subsequent intake to match the energy in the preload (e.g., Ref. [2]), but other studies find no reduction in eating in response to carbohy- drate preloads (e.g., Ref. [10]). Preloads based primarily on fat have generally been found to have less effect on subsequent eating behaviour (e.g., Refs. [11– 13]), although again, reduced intake has been reported in some studies [14], and when the fat in the preload was fully disguised, the effects of fat and carbohydrate were identical [15]. Thus, under appropriate conditions, it is possible to find evidence for reductions in food intake following disguised fat and carbohydrate preloads, suggesting that the post-ingestive effects of these nutrients generate some form of satiety signal, which helps modulate subsequent eating [16]. This conclusion is further supported from studies where any orosensory feedback from the preload is avoided by infusing nutrients directly into the stomach or intestine [17,18]. Current models of appetite control suggest that meal size is determined by a complex interaction among cognitive, sensory and physiological cues generated by prior food consumption. The use of disguised oral preloads and direct infusions of nutrients into the gut have helped our under- standing of the nature of these physiological cues, but the finding, that the short-term reduction in intake seen after high-energy preloads rarely matches the energy content in the preload, shows that post-ingestive cues alone are insuf- ficient for accurate regulation of short-term intake. The recent observation, that increasing the palatability of the test meal reduces the effects of energetic preloads [15], shows the interactive nature of satiety. A further factor, which may be important in this context, is the consumers’ 0031-9384/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved. PII:S0031-9384(01)00502-9 * Corresponding author. Tel.: +44-1273-678617; fax: +44-1273- 678611. E-mail address: martin@biols.sussex.ac.uk (M.R. Yeomans). Physiology & Behavior 73 (2001) 533 – 540