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 ...

Abbreviations: EB, energy balance; EE, energy expenditure; EI, energy intake; Hex, high exercise level; Mex, medium exercise level; Nex, no exercise. Physical activity has the potential to modulate appetite control by improving the sensitivity of the physiological satiety signalling system, by adjusting macronutrient preferences or food choices and by altering the hedonic response to food. There is evidence for all these actions. Concerning the impact of physical activity on energy balance, there exists a belief that physical activity drives up hunger and increases food intake, thereby rendering it futile as a method of weight control. There is, however, no evidence for such an immediate or automatic effect. Short (1-2 d)-term and medium (7-16 d)-term studies demonstrate that men and women can tolerate substantial negative energy balances of ≤ 4 MJ energy cost/d when performing physical activity programmes. Consequently, the immediate effect of taking up exercise is weight loss (although this outcome is sometimes difficult to assess due to changes in body composition or fluid compartmentalization). However, subsequently food intake begins to increase in order to provide compensation for about 30 % of the energy expended in activity. This compensation (up to 16 d) is partial and incomplete. Moreover, subjects separate into compensators and non-compensators. The exact nature of these differences in compensation and whether it is actually reflective of non-compliance with protocols is yet to be determined. Some subjects (men and women) performing activity with a cost of ≤ 4 MJ/d for 14 d, show no change in daily energy intake. Conversely, it can be demonstrated that when active individuals are forced into a sedentary routine food intake does not decrease to a lower level to match the reduced energy expenditure. Consequently, this situation creates a substantial positive energy balance accompanied by weight gain. The next stage is to further characterize the compensators and non-compensators, and to identify the mechanisms (physiological or behavioural) that are responsible for the rate of compensation and its limits.Energy balance: Physical activity: Appetite EB, energy balance; EE, energy expenditure; EI, energy intake; Hex, high exercise level; Mex, medium exercise level; Nex, no exercise.

The effects of incremental exercise on appetite, energy intake (EI), expenditure (EE) and balance (EB) in lean men and women were examined. Six men (age 29·7 (SD 5·9) years, weight 75·2 (SD 15·3) kg, height 1·75 (SD 0·11) m) and six women (age 24·7 (SD 5·9) years, weight 66·7 (SD 9·10) kg, height 1·70 (SD 0·09) m) were each studied three times during a 16 d protocol, corresponding to no additional exercise (Nex), moderate-intensity exercise (Mex; 1·5 -2·0 MJ/d) and high-intensity exercise (Hex; 3·0 -4·0 MJ/d) regimens. Subjects were fed to EB during days 1 -2, and during days 3-16 they fed ad libitum from a medium-fat diet of constant composition. Daily EE, assessed using the doubly labelled water method, was 9·2, 11·6 and 13·7 MJ/d (P, 0·001; SED 0·45) for the women and 12·2, 14·0 and 16·7 MJ/d (P¼ 0·007; SED 1·11) for the men on the Nex, Mex and Hex treatments, respectively. EI was 8·3, 8·6 and 9·9 MJ/d (P¼ 0·118; SED 0·72) for the women and 10·6, 11·6 and 12·0 MJ/d (P¼ 0·031; SED 0·47) for the men, respectively. On average, subjects compensated for about 30 % of the exercise-induced energy deficit. However, the degree of compensation varied considerably among individuals. The present study captured the initial compensation in EI for exercise-induced energy deficits. Total compensation would take a matter of weeks.Exercise: Appetite: Energy balance: Feeding behaviour: Human studies A low level of physical activity, typical of Western society, is deemed conducive to weight gain (1,2) . In addition, it is believed by some that increases in physical activity will promote weight loss (3) . However, individuals are unlikely to continue to lose weight over prolonged periods if they elevate daily energy expenditure (EE) by increasing physical activity (for example, Sum et al. ). It is intuitively obvious that energy intake (EI) will eventually begin to track EE, and body weight will stabilise. However, the exact manner in which changes in levels of physical activity influence feeding behaviour over periods long enough to affect energy balance (EB) is not clearly understood. There is a large body of literature on the effect of training programmes on body weight and composition in athletes (5 -10) . Likewise, a number of important studies have examined the effects of training programmes on weight loss in obese subjects (for example, Schoeller et al. (11) and Saris (12) ). Fewer studies have examined the relationship between changes in EE and feeding behaviour in normally sedentary, non-obese subjects who do not have a pre-conceived goal of weight reduction or a training programme. The reviews of King et al. of the effects of exercise regimens on appetite and EI show that in short-to mediumterm intervention studies (often no longer than 2-5 d), 19 % report an increase in EI after exercise; 65 % show no change and 16 % show a decrease (13 -15) . Longer-term studies that measure body composition suggest some fat mass is lost but lean body mass tends to be preserved in response to exercise regimens, depending on the ...

Reducing a level of physical activity from 1.8 to 1.4 x RMR can markedly affect EB. A sedentary routine does not induce a compensatory reduction of EI and leads to a significantly positive EB, most of which is stored as fat.