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I review and critique restraint theory and develop a 3-factor model of dieting behavior. The factors--frequency of dieting and overeating, current dieting, and weight suppression--are embedded within a 3-dimensional grid that also considers mechanisms mediating the effects of dieting and the influence of weight status. I argue that the eating behavior exhibited by restrained eaters stems from their frequent dieting and overeating in the past rather than from their current state of dietary or cognitive restraint. Evidence is reviewed, indicating that current dieting and weight suppression have different effects on eating than does restraint. The 3-factor model is used to reinterpret findings consistent with restraint theory and to explain findings inconsistent with restraint theory. Finally, clinical and research implications of the 3-factor model are discussed.

Background:The 21-item Three-Factor Eating Questionnaire (TFEQ-R21) is a scale that measures three domains of eating behavior: cognitive restraint (CR), uncontrolled eating (UE) and emotional eating (EE). Objectives: To assess the factor structure and reliability of TFEQ-R21 (and if necessary, refine the structure) in diverse populations of obese and non-obese individuals. Design: Data were obtained from obese adults in a United States/Canadian clinical trial (n ¼ 1741), and overweight, obese and normal weight adults in a US web-based survey (n ¼ 1275). Confirmatory factor analyses were employed to investigate the structure of TFEQ-R21 using baseline data from the clinical trial. The model was refined to obtain adequate fit and internal consistency. The refined model was then tested using the web-based data. Relationships between TFEQ domains and body mass index (BMI) were examined in both populations. Results: Clinical data indicated that TFEQ-R21 needed refinement. Three items were removed from the CR domain, producing the revised version TFEQ-R18V2 (Comparative Fit Index (CFI) ¼ 0.91). Testing TFEQ-R18V2 in the web-based sample supported the revised structure (CFI ¼ 0.96; Cronbach's coefficient a of 0.78-0.94). Associations with BMI were small. In the clinical study, the CR domain showed a significant and negative association with BMI. On the basis of the web-based survey, it was shown that the relationship between BMI and CR is population-dependent (obese versus non-obese, healthy versus diabetics). Conclusions: In two independent datasets, the TFEQ-R18V2 showed robust factor structure and good reliability. It may provide a useful tool for characterizing UE, CR and EE.

The finding that dietary restraint scales predict onset of bulimic pathology has been interpreted as suggesting that dieting causes this eating disturbance, despite the dearth of evidence that these scales are valid measures of dietary restriction. The authors conducted 4 studies that tested whether dietary restraint scales were inversely correlated with unobtrusively measured caloric intake. These studies, which varied in foods consumed, settings, and populations, indicated that common dietary restraint scales were largely uncorrelated with acute caloric intake. Results suggest that these scales are not valid measures of short-term dietary restriction and imply that it may be prudent to reinterpret findings from studies thai use these scales, including those that suggest dietary restraint is a risk factor for bulimic pathology.

Background: The Power of Food Scale (PFS) was developed to assess the psychological impact of today's food-abundant environments. Objective: To evaluate the structure of the PFS in diverse populations of obese and nonobese individuals. Design: Data were obtained from obese adults in a clinical trial for a weight management drug (n ¼ 1741), and overweight, obese and normal weight adults in a Web-based survey (n ¼ 1275). Exploratory and confirmatory factor analyses were used to investigate the PFS structure using the clinical data. The model developed was then tested using the Web-based data. Relationships between PFS domains and body mass index (BMI) were examined. Logistic regression was used in the Web-based survey to evaluate the association between obesity status and PFS scores. Results: Clinical data indicated that the scale was best represented by a 15-item version with three subscale domains and an aggregate domain (average of three domains); this was confirmed with data from the Web-based survey (Comparative Fit Index: 0.95 and 0.94 for the clinical and Web-based studies, respectively). Cronbach's a for both data sets was high, ranging from 0.81 to 0.91. The relationships between BMI and each domain were weak (and approximately linear). A full category increase in PFS domain score (range 1-5) increased the odds of being obese 1.6-2.3 times. Conclusions: The 15-item PFS is best represented by three domains and an aggregate domain. The PFS may provide a useful tool to evaluate the effects of obesity treatments on feelings of being controlled by food in an obesogenic food environment.

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LOWE, MICHAEL R. AND ALLEN S. LEVINE. Eating motives and the controversy over dieting: eating less than needed versus less than wanted. Obes Res. 2005;13:797-806. Anti-dieting sentiment has grown in recent years. Critics of restrained eating suggest that it evokes counter-regulatory responses that render it ineffective or even iatrogenic. However, restrained eaters are not in negative energy balance and overweight individuals show reduced eating problems when losing weight by dieting. A distinction is often drawn between physiological and psychological hunger, and neuroscience research has shown that there is a neurophysiological reality underlying this distinction. The brain has a homeostatic system (activated by energy deficits) and a hedonic system (activated by the presence of palatable food). The omnipresence of highly palatable food in the environment may chronically activate the hedonic appetite system, producing a need to actively restrain eating not just to lose weight but to avoid gaining it. Just as restricting energy intake below homeostatic needs produces physiological deprivation, restricting intake of palatable foods may produce "perceived deprivation" despite a state of energy balance. In summary, the motivation to eat more than one needs appears to be every bit as real, and perhaps every bit as powerful, as the motivation to eat when energy deprived.