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.

To date, no study has directly and simultaneously measured the discrepancy between what people actually eat and what they report eating under observation in the context of energy balance (EB). The present study aimed to objectively measure the 'extent' and 'nature' of misreporting of dietary intakes under conditions in which EB and feeding behaviour were continuously monitored. For this purpose, a total of fifty-nine adults were recruited for 12 d, involving two 3 d overt phases and two 3 d covert phases of food intake measurement in a randomised cross-over design. Subjects had ad libitum access to a variety of familiar foods. Food intake was covertly measured using a feeding behaviour suite to establish actual energy and nutrient intakes. During the overt phases, subjects were instructed to self-report food intake using widely accepted methods. Misreporting comprised two separate and synchronous phenomena. Subjects decreased energy intake (EI) when asked to record their food intake (observation effect). The effect was significant in women (28 %, P, 0·001) but not in men (2 3 %, P, 0·277). The reported EI was 5 to 21 % lower (reporting effect) than the actual intake, depending on the reporting method used. Semi-quantitative techniques gave larger discrepancies. These discrepancies were identical in men and women and non-macronutrient specific. The 'observation' and 'reporting' effects combined to constitute total misreporting, which ranged from 10 to 25 %, depending on the intake measurement assessed. When studied in a laboratory environment and EB was closely monitored, subjects under-reported their food intake and decreased the actual intake when they were aware that their intake was being monitored.

The relevance of measuring intake to the nutritional and behavioural sciencesUnderstanding the mechanisms controlling human appetite and energy intake (EI) is fundamental to nutritional science since it is through a balance between EI and energy expenditure (EE) that body weight and composition are maintained and functional integrity is sustained. The recent resurgence of interest in the study of feeding behaviour and the physiological control of food intake (FI) is mainly due to the rapidly increasing proportion of overweight and obese individuals in Western society (White et al. 1991; Department of Health, 1995). It is widely accepted that the uncoupling of EI from EE is largely responsible for these secular trends in body weight. The ability to measure food, energy and nutrient (FEN) intake is critical to our understanding of the processes producing these secular trends. The mechanisms controlling feeding are multifactorial and complex in nature and are generally characterized by an on-going interaction between physiology and behaviour. In recent years an increasing number of studies have incorporated both behavioural and nutritional measures of intake in attempting to understand the quantitative importance of a number of factors (e.g. diet composition, exercise, disease) thought to exert important influences on appetite and energy balance (EB). The measurement of intake in the laboratory is also critical in establishing mechanistic links between other aspects of diet and disease. The relationship between dietary antioxidant intake and oxidative damage to somatic DNA, the effects of dietary lipid profile on immune function and the influence of fibre on mineral bioavailability are three of many possible examples. Such carefully controlled laboratory protocols are crucial in establishing the existence and importance of diet in the promotion of health and the development of disease.There are, thus, two basic forms of intake measurement in the laboratory. The first allows subjects to control their own FEN intake within the constraints of the experimental design. Under these conditions measures of FEN intake result from the subject's behavioural response to the experimental manipulation and any other factors which may influence their behaviour at the time. The second type of FEN intake measurement in the laboratory is a measure of a fixed mandatory intake (termed 'fixed-intake' studies here). In such studies the subject's feeding behaviour has been clamped and the measurement is not as susceptible to 'behavioural noise' provided the subject is compliant with the protocol and the experiment is rigorously designed. Fixed-intake studies are therefore less fraught with methodological difficulties relating to the effects of the experimental environment on behaviour. The majority of errors under these conditions will be of a technical nature, while studies which allow subjects to alter their own intakes are subject to both technical and behavioural errors. Because behaviourally-oriented studies are subject to both type...

Objective: To compare energy expenditure (EE) measured by doubly labeled water (DLW) with other measures, both physical and based on subjective questionnaires. Design: A comparison of methods in a stratified sample of adult volunteers. Setting: The feeding behaviour suite (FBS) at the Rowett Research Institute, Aberdeen. Subjects: A total of 59 subjects, stratified for age, sex and body mass index (BMI). Interventions: EE was assessed by DLW (validated using measurements of energy balance), heart rate monitor (HRM), activity monitor (Caltrac), 24-h physical activity diary (PAD) and 7-day physical activity recall. Energy intake was assessed using covert (investigator-weighed) food intake (EI). Data were collected over a 12-day period of residence in the Rowett's FBS. Results: No methods correlated highly with physical activity assessed by DLW. Physical methods correlated more closely than did subjective recording. All methods (except EI) significantly underestimated EE, estimated by DLW. There were no significant differences in association between methods and sex, age, BMI or fat-free mass. Conclusion: EE is difficult to measure precisely or accurately with current approaches but physical methods are slightly better than subjective accounts.

22 BACKGROUND/OBJECTIVES Comparing reported energy intakes to estimated energy 23requirements as multiples of Basal Metabolic Rate (Ein:BMR) is an established method of 24 identifying implausible food intake records. The present study aimed to examine the validity 25 of self-reported food intakes believed to be plausible. 26 SUBJECTS/METHODS One hundred and eighty men and women were provided with all 27 food and beverages for two consecutive days in a residential laboratory setting. Subjects self-28 reported their food and beverage intakes using the weighed food diary method (WDR). 29Investigators covertly measured subjects' actual consumption over the same period. Subjects 30 also reported intakes over four consecutive days at home. Basal Metabolic Rate was 31 measured by indirect calorimetry. 32 RESULTS Average reported energy intakes were significantly lower than actual intakes 33 (11.2MJ/d and 11.8MJ/d respectively, p < 0.001). Two-thirds (121) of the WDR were under-34 reported to varying degrees. Only five of these were considered as implausible using an 35Ein:BMR cut-off value of 1.03 x BMR. Under-reporting of food and beverage intakes, as 36 measured by the difference between reported and actual intake, was evident at all levels of 37 Ein;BMR. Reported energy intakes were lower still (10.2MJ/d) while subjects were at home. 38 CONCLUSION Under-recording of self-reported food intake records was extensive but very 39 few under-reported food intake records were identified as implausible using energy intake to 40 BMR ratios. Under-recording was evident at all levels of energy intake. 41 42

Leading obesity researchers from across Europe assembled in Aberdeen, Scotland, in January 2003 to consider how to increase the impact of European obesity research. The workshop was funded by the European Commission and hosted by the Rowett Research Institute, Aberdeen. The delegates identified the need to (i) develop a portfolio of studies that integrate genetics and mechanisms through parallel study of humans and animal models and (ii) establish major intervention studies in weight management and early life nutrition. It was recommended that these goals would be best achieved under the umbrella of a virtual European Obesity Research Institute, or Network of Excellence in Obesity Research under Framework Programme 6, that would facilitate harmonization of methodology, manage centralized standardized resources, coordinate training initiatives, workshops and working groups, and increase focus.

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