This present paper reviews the reliability and validity of visual analogue scales (VAS) in terms of (1) their ability to predict feeding behaviour, (2) their sensitivity to experimental manipulations, and (3) their reproducibility. VAS correlate with, but do not reliably predict, energy intake to the extent that they could be used as a proxy of energy intake. They do predict meal initiation in subjects eating their normal diets in their normal environment. Under laboratory conditions, subjectively rated motivation to eat using VAS is sensitive to experimental manipulations and has been found to be reproducible in relation to those experimental regimens. Other work has found them not to be reproducible in relation to repeated protocols. On balance, it would appear, in as much as it is possible to quantify, that VAS exhibit a good degree of within-subject reliability and validity in that they predict with reasonable certainty, meal initiation and amount eaten, and are sensitive to experimental manipulations. This reliability and validity appears more pronounced under the controlled (but more arti®cial) conditions of the laboratory where the signal : noise ratio in experiments appears to be elevated relative to real life. It appears that VAS are best used in within-subject, repeated-measures designs where the effect of different treatments can be compared under similar circumstances. They are best used in conjunction with other measures (e.g. feeding behaviour, changes in plasma metabolites) rather than as proxies for these variables. New hand-held electronic appetite rating systems (EARS) have been developed to increase reliability of data capture and decrease investigator workload. Recent studies have compared these with traditional pen and paper (P&P) VAS. The EARS have been found to be sensitive to experimental manipulations and reproducible relative to P&P. However, subjects appear to exhibit a signi®cantly more constrained use of the scale when using the EARS relative to the P&P. For this reason it is recommended that the two techniques are not used interchangeably.Visual analogue scales: Electronic appetite rating systems: Appetite: Hunger A speci®c advantage of studying the behaviour of human subjects (relative to animals) is that human subjects can be asked a number of questions relating to their motivation, sensations and attitudes. Psychologists and clinicians have long used subjective feelings of bodily sensations or functions to help in research investigations and patient management. Such assessments have been carried out in diverse conditions to examine a variety of`functions': quality of life (Hunt et al. 1981), pain (Ohnhaus & Alder, 1975;Downie et al. 1978), sex, libido, depression, anxiety (Keys et al. 1950, nausea and appetite (Hill & Blundell, 1982). Freyd (1923) has pointed out that such ratings are the only practical equivalents of objective measurements for many types of psychological phenomena, especially introspective or verbally reported data.Attempting to understand the role of food and ...

OBJECTIVE: This study examined the effects of covert alterations in the energy density (ED) of mixed, medium fat (MF) diets on ad libitum food and energy intake (EI), subjective hunger and body weight in humans. DESIGN: Randomised cross-over design. Subjects were each studied three times (factorial design), during 14 d, throughout which they had ad libitum access to one of three covertly-manipulated MF diets. SUBJECTS: Six healthy men, mean age (s.e.m.) 30.0 y (12.76 y), mean weight 71.67 kg (19.80 kg); mean height 1.79 m (0.22 m), body mass index (BMI) 22.36 (2.60) kg/m 2 , were studied. The fat, carbohydrate (CHO) and protein in each diet (as a proportion of the total energy) and energy density (ED) were, low-ED (LED), 38:49:13%; 373 kJ/100 g; medium-ED (MED), 40:47:13%; 549 kJ/100 g; high-ED (HED), 39:48:13%; 737 kJ/100 g. Subjects could alter the amount but not the composition of foods eaten. They were resident in (but not con®ned to) a metabolic suite throughout the study. RESULTS: Solid food intake decreased as ED increased, giving mean values of 2.84, 2.51 and 2.31 kg/d, respectively. This was insuf®cient to defend energy balance, since energy intake increased with increasing ED (F (2,10) 16.08; P`0.001) giving mean intakes of 10.12, 12.80 and 16.17 MJ/d, respectively. Rated pleasantness of food (measured on visual analogue scales) was not signi®cantly different between diets nor was subjective hunger different between the LED, MED and HED diets, respectively. Diet signi®cantly affected body weight (F (2,10) 4.62; P 0.038), producing changes of 71.20, 0.02 and 0.95 kg, respectively, by day 14. CONCLUSION: Dietary ED can in¯uence EI and body weight, since changes in amount eaten alone are insuf®cient to defend energy balance, when subjects feed on unfamiliar diets and diet selection is precluded. Comparison with our previous studies suggest that there was compensation in solid food intake when ED was altered using mixed diets (as in this study) compared to previous studies which primarily used fat or CHO to alter dietary ED.

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OBJECTIVE:To investigate the effects of a yoghurt containing a novel fat emulsion on energy and macronutrient intakes up to 8 h post-consumption in non-overweight, overweight and obese subjects, and to assess energy compensation over the following 24 h. DESIGN: A double-blind, placebo-controlled, within-subject crossover design was used. Twenty (10 female, 10 male) nonoverweight (body mass index (BMI) 20 -24.9 kg=m 2 ), 20 (10 female, 10 male) overweight (BMI 25 -29.9 kg=m 2 ) and 20 (13 female, 7 male) obese (BMI > 30 kg=m 2 ) subjects participated in the study. Subjects were given in random order, 7 days apart, either a 200 g portion of a test (5 g of a novel fat emulsion þ 1 g milk fat) or control (6 g milk fat) yoghurt at 09:00 h. At 4 and 8 h post-consumption subjects were given ad libitum access to a range of foods. Amounts of food consumed were determined by pre and post-covert weighing of individual serving dishes. Over the following 24 h subjects weighed and recorded all food intakes. RESULTS: Mean energy intakes were significantly lower after the test yoghurt compared with the control yoghurt in nonoverweight (3.79 vs 5.43 MJ; P < 0.01) and overweight (4.43 vs 6.12 MJ; P < 0.001) subjects 4 h post-consumption and in nonoverweight (3.82 vs 5.38 MJ; P < 0.001), overweight (3.94 vs 5.80 MJ; P < 0.001) and obese (4.91 vs 6.26 MJ; P < 0.01) subjects 8 h post-consumption. The corresponding macronutrient intakes were also significantly reduced in non-overweight and overweight subjects (P < 0.01) at 4 h post-consumption and in all subjects 8 h post-consumption (P < 0.01). In the total group, energy intakes over the following 24 h were also significantly reduced (6.35 vs 7.70 MJ; P < 0.01) after the test yoghurt relative to the control yoghurt. CONCLUSIONS: These results suggest that the effects of this novel fat emulsion are maintained at least up to 8 h and are evident in non-overweight, overweight and obese subjects.

BACKGROUND: The satiating properties of fat remain poorly understood, particularly with reference to its physicochemical characteristics. OBJECTIVE: To investigate the short-term effects of consumption of yoghurt containing either a novel fat emulsion or normal milk fat, on the energy and macronutrient intakes of non-obese subjects. DESIGN: Two double-blind, placebo-controlled, within-subject crossover studies were conducted three months apart. Twenty-nine (15 F, 14 M) and thirty (16 F, 14 M) subjects participated in Study 1 and Study 2 respectively. In each study, subjects were given in random order, 7 days apart, either a 200 g portion of a test (5 g of a novel fat emulsion 1 g milk fat) or control (6 g milk fat) yoghurt at 1300 h. At 4 h post-consumption subjects were given ad libitum access to a range of foods. Amounts of food consumed by individuals were determined by pre-and post-covert weighing of individual serving dishes. RESULTS: Mean energy intakes were signi®cantly lower after the test yoghurt compared with the control yoghurt in Study 1 (6.4 vs 7.6 MJ; P`0.001), Study 2 (6.9 vs 7.9 MJ; P`0.001), and for both studies combined (6.7 vs 7.7 MJ; P`0.001). The corresponding fat intakes in Study 1, Study 2 and in the combined studies were all signi®cantly reduced (P`0.001). Protein and carbohydrate intakes were also signi®cantly reduced in Study 1 (P`0.05), Study 2 (P`0.01), and for the combined studies (P`0.001). CONCLUSIONS: These results suggest that the physicochemical characteristics of small amounts of dietary fat affect short-term satiety.