Normal protein intake is required for body weight loss and weight maintenance, and elevated protein intake for additional preservation of resting energy expenditure and fat free mass.

Energy-restricted high-protein diets (HPDs) have shown favorable results for body weight (BW) management, yet studies differ in their outcomes depending on the dietary protein content. Our objective was to determine the effects of dietary protein content on BW loss-related variables during a 6-mo energy restriction with the use of diets containing protein at the level of requirement [normal-protein diet (NPD), 0.8 g · kg BW(-1) (.) d(-1)] and above (HPD, 1.2 g · kg BW(-1) (.) d(-1)). In overweight and obese participants (24 men and 48 women), BW, body composition, and metabolic responses were assessed before and after subsequent energy intakes of 100, 33, and 67% of the original individual daily energy requirements. Protein intake was consistent in the NPD (0.8 ± 0.3 g · kg BW(-1) (.) d(-1)) and HPD (1.2 ± 0.3 g · kg BW(-1) (.) d(-1)) groups throughout the study (P < 0.001). BMI and body fat mass similarly decreased in the NPD and HPD groups (P < 0.01). Fat free mass (FFM), resting energy expenditure (REE) compared with predicted REE, and diastolic blood pressure (DBP) changed favorably with the HPD compared with the NPD group after BW loss (P < 0.05). A NPD of 0.8 g · kg BW(-1) (.) d(-1) is sufficient for BW management, whereas a HPD of 1.2 g · kg BW(-1) (.) d(-1) is necessary for preservation of REE and a stronger initial sparing effect of FFM and lowering of DBP.

Increased sensitivity to food cues in the fasted state and decreased inhibitory control in the satiated state in the overweight.

BACKGROUND: Flexibility of food reward-related brain signaling (FRS) between food and nonfood stimuli may differ between overweight and normal-weight subjects and depend on a fasted or satiated state. OBJECTIVE: The objective was to assess this flexibility in response to visual food and nonfood cues. DESIGN: Twenty normal-weight [mean ± SEM BMI (in kg/m(2)) = 22.7 ± 0.2; mean ± SEM age = 22.4 ± 0.4 y] and 20 overweight (BMI = 28.1 ± 0.3; age = 24.0 ± 0.7 y) participants completed 2 fMRI scans. Subjects arrived in a fasted state and consumed a breakfast consisting of 20% of subject-specific energy requirements between 2 successive scans. A block paradigm and a food > nonfood contrast was used to determine FRS. RESULTS: An overall stimulus × condition × subject group effect was observed in the anterior cingulate cortex (ACC) (P < 0.006, F((1,38)) = 9.12) and right putamen (P < 0.006, F((1,38)) = 9.27). In all participants, FRS decreased from the fasted to the satiated state in the cingulate (P < 0.005, t((39)) = 3.15) and right prefrontal cortex (PFC) (P < 0.006, t((39)) = 3.00). In the fasted state, they showed FRS in the PFC (P < 0.004, t((39)) = 3.17), left insula (P < 0.009, t((39)) = 2.95), right insula (P < 0.005, t((39)) = 3.12), cingulate cortex (P < 0.004, t((39)) = 3.21), and thalamus (P < 0.006, t((39)) = 2.96). In the satiated state, FRS was limited to the left insula (P < 0.005, t((39)) = 3.21), right insula (P < 0.006, t((39)) = 3.04), and cingulate cortex (P < 0.005, t((39)) = 3.15). Regarding subject group, in the fasted state, FRS in the ACC was more pronounced in overweight than in normal-weight subjects (P < 0.005, F((1,38)) = 9.71), whereas in the satiated state, FRS was less pronounced in overweight than in normal-weight subjects in the ACC (P < 0.006, F((1,38)) = 9.18) and PFC (P < 0.006, F((1,38)) = 8.86), which suggests lower inhibitory control in the overweight. CONCLUSION: FRS was higher in the overweight in the satiated state; however, when sufficiently satiated, the overweight showed decreased inhibitory control signalling, which facilitates overeating. This trial was registered in the Dutch clinical trial register as NTR2174.

Protein v. carbohydrate intake differentially affects liking- and wanting-related brain signalling.

Extreme macronutrient intakes possibly lead to different brain signalling. The aim of the present study was to determine the effects of ingesting high-protein v. high-carbohydrate food on liking and wanting task-related brain signalling (TRS) and subsequent macronutrient intake. A total of thirty female subjects (21.6 (SD 2.2) years, BMI 25.0 (SD 3.7) kg/m²) completed four functional MRI scans: two fasted and two satiated on two different days. During the scans, subjects rated all food items for liking and wanting, thereby choosing the subsequent meal. The results show that high-protein (PROT) v. high-carbohydrate (CARB) conditions were generated using protein or carbohydrate drinks at the first meal. Energy intake and hunger were recorded. PROT (protein: 53.7 (SD 2.1) percentage of energy (En%); carbohydrate: 6.4 (SD 1.3) En%) and CARB conditions (protein: 11.8 (SD 0.6) En%; carbohydrate: 70.0 (SD 2.4) En%) were achieved during the first meal, while the second meals were not different between the conditions. Hunger, energy intake, and behavioural liking and wanting ratings were decreased after the first meal (P< 0.001). Comparing the first with the second meal, the macronutrient content changed: carbohydrate -26.9 En% in the CARB condition, protein -37.8 En% in the PROT condition. After the first meal in the CARB condition, wanting TRS was increased in the hypothalamus. After the first meal in the PROT condition, liking TRS was decreased in the putamen (P< 0.05). The change in energy intake from the first to the second meal was inversely related to the change in liking TRS in the striatum and hypothalamus in the CARB condition and positively related in the PROT condition (P< 0.05). In conclusion, wanting and liking TRS were affected differentially with a change in carbohydrate or protein intake, underscoring subsequent energy intake and shift in macronutrient composition.

Relatively high-protein or 'low-carb' energy-restricted diets for body weight loss and body weight maintenance?

BACKGROUND: 'Low-carb' diets have been suggested to be effective in body weight (BW) management. However, these diets are relatively high in protein as well. OBJECTIVE: To unravel whether body-weight loss and weight-maintenance depends on the high-protein or the 'low-carb' component of the diet. DESIGN: Body-weight (BW), fat mass (FM), blood- and urine-parameters of 132 participants (age=50 ± 12 yr; BW=107 ± 20 kg; BMI=37 ± 6 kg/m(2); FM=47.5 ± 11.9 kg) were compared after 3 and 12 months between four energy-restricted diets with 33% of energy requirement for the first 3 months, and 67% for the last 9 months: normal-protein normal-carbohydrate (NPNC), normal-protein low-carbohydrate (NPLC); high-protein normal-carbohydrate (HPNC), high-protein low-carbohydrate (HPLC); 24h N-analyses confirmed daily protein intakes for the normal-protein diets of 0.7 ± 0.1 and for the high-protein diets of 1.1 ± 0.2g/kg BW (p<0.01). RESULTS: BW and FM decreased over 3 months (p<0.001): HP (-14.1 ± 4 kg; -11.9 ± 1.7 kg) vs. NP (-11.5 ± 4 kg; -9.3 ± 0.7 kg) (p<0.001); LC (-13.5 ± 4 kg; -11.0 ± 1.2 kg) vs. NC (-12.3 ± 3 kg; -10.3 ± 1.1 kg) (ns). Diet × time interaction showed HPLC (-14.7 ± 5 kg; -11.9 ± 1.6 kg) vs. HPNC (-13.8 ± 3 kg; -11.9 ± 1.8 kg) (ns); NPLC (-12.2 ± 4 kg; -10.0 ± 0.8 kg) vs. NPNC (-10.7 ± 4 kg; -8.6 ± 0.7 kg) (ns); HPLC vs. NPLC (p<0.001); HPNC vs. NPNC (p<0.001). Decreases over 12 months (p<0.001) showed HP (-12.8 ± 4 kg; -9.1 ± 0.8 kg) vs. NP (-8.9 ± 3 kg; -7.7 ± 0.6 kg) (p<0.001); LC (-10.6 ± 4 kg; -8.3 ± 0.7 kg) vs. NC (11.1 ± 3 kg; 9.3 ± 0.7 kg) (ns). Diet × time interaction showed HPLC (-11.6 ± 5 kg ; -8.2 ± 0.7 kg) vs. HPNC (-14.1 ± 4 kg; -10.0 ± 0.9 kg) (ns); NPNC (-8.2 ± 3 kg; -6.7 ± 0.6 kg) vs. NPLC (-9.7 ± 3 kg; -8.5 ± 0.7 kg) (ns); HPLC vs. NPLC (p<0.01); HPNC vs. NPNC (p<0.01). HPNC vs. all other diets reduced diastolic blood pressure more. Relationships between changes in BW, FM, FFM or metabolic parameters and energy percentage of fat in the diet were not statistically significant. Metabolic profile and fat-free-mass were improved following weight-loss. CONCLUSION: Body-weight loss and weight-maintenance depends on the high-protein, but not on the 'low-carb' component of the diet, while it is unrelated to the concomitant fat-content of the diet.

Satiating capacity and post-prandial relationships between appetite parameters and gut-peptide concentrations with solid and liquefied carbohydrate.

BACKGROUND: Differences in satiating capacity of liquid and solid meals are unclear. OBJECTIVE: Investigating appetite parameters, physiological measurements and within-subject relationships after consumption of a single macronutrient, subject-specific carbohydrate meal in liquefied versus solid form, controlled for energy density, weight and volume. DESIGN: In a cross-over design, ten male subjects (age = 21.1±3.9 y, BMI = 22.4±1.2 kg/m(2)) consumed a solid (CS, whole peaches +750 ml water) and liquefied carbohydrate (CL, peach blended in 500 ml water +250 ml water) lunch. Appetite profiles, insulin-, glucose- and ghrelin concentrations were measured over three hours. Post-prandial relationships between appetite and blood parameters were calculated using subject-specific regression analyses. RESULTS: Fullness ratings were higher in the CL (85±5 mm) compared to the CS condition (73±8 mm) at 20 min (p<0.03). Glucose concentrations peaked 20 to 30 min after the start of the lunch in the CL condition, and 30 to 40 min after start of the CS condition. Correspondingly, insulin concentrations were peaked at 20-30 min in the CL condition, and at 30-40 min in the CS condition. AUC or condition x time interactions were not different comparing the CL and the CS condition. Insulin was significantly higher in the CS compared to the CL condition 40 min after the start of the lunch (p<0.05). Fullness scores were significantly related to insulin concentrations but not to glucose concentrations; desire to eat scores were significantly associated with ghrelin concentrations in both, the CL and the CS condition. The relationship between fullness scores and glucose concentrations was not statistically significant. CONCLUSION: Liquefied and solid carbohydrate meals do not differ in satiating capacity, supported by appetite profile and relevant blood parameters. Postprandially, fullness and desire to eat were associated with respectively insulin and ghrelin concentrations.

Sex differences in HPA axis activity in response to a meal.

BACKGROUND: Sex may influence the relationship between HPA axis functioning and obesity. This has been suggested to be due to sex-specific differences in body composition, body fat distribution and psychological variables. Age and the use of oral contraceptives may also influence the relationship between HPA axis functioning and obesity. OBJECTIVE: To systematically investigate whether body composition, body fat distribution, psychological variables, age, or possible oral contraceptive use contribute to sex differences in HPA axis activity in response to a meal. METHODS: Subjects were men (n=19) and women (n=19) between 18 and 51 years old with BMI between 20.3 and 33.2 kg/m(2). HPA axis activity was measured by salivary free cortisol levels before consuming a meal, and at 45, 75 and 125 min postprandial on four repeated test days. Anthropometric and body composition measurements were performed. Questionnaires were used to assess cognitive eating behavior and trait anxiety level. RESULTS: No differences between the test days in postprandial cortisol responses appeared. Responses were significantly higher in men compared with women (p<.05). No significant correlations were found between cortisol concentrations and sex-specific body composition or body fat distribution. Psychological variables did not contribute to differences in cortisol responses after a meal between men and women. In women, baseline cortisol concentrations correlated inversely with age (p=.024). CONCLUSION: Higher HPA axis activity following a meal in men vs. women remained irrespective of sex-specific differences in body composition, body fat distribution, psychological variables, or in age. In women baseline cortisol concentrations were age-dependent.

High HPA-axis activation disrupts the link between liking and wanting with liking and wanting related brain signaling.

BACKGROUND: Eating behavior changes under stress, i.e. during high HPA-axis activation. AIM: Assessment of effects of high versus low HPA-axis activation on liking and wanting related brain signaling in relevant regions. METHODS: 15 female subjects (21.5±0.4 years, BMI=22.2±0.4) completed fMRI scans on 2 days, in a fasted as well as a satiated condition on each day. The days were sorted by HPA-axis activation, resulting in two sufficiently separated HPA-axis states which were statistically confirmed (p<.05). During scans, subjects rated liking and wanting for food images; wanting indicated food choice for the subsequent meal. Energy-intake, hunger and fullness were additionally recorded. RESULTS: Hunger changed significantly over the meal (p<.001). Energy intake was lower during the second meal (p<.001). Behavioral wanting was lower after breakfast (p<.01), behavioral liking did not change. During low HPA-activation, liking task related signaling (TRS) pre-meal in the anterior insula predicted behavioral liking, wanting TRS in the anterior insula, nucleus accumbens and thalamus predicted behavioral wanting. During high HPA-activation, these relationships were not present pre-meal, but post-meal behavioral liking was predicted in the nucleus accumbens and wanting in the caudate. CONCLUSION: High HPA-axis activation disrupted and redirected the connection of behavioral liking/wanting with the specifically associated brain signaling in relevant regions.

Differences between liking and wanting signals in the human brain and relations with cognitive dietary restraint and body mass index.

BACKGROUND: Eating behavior is determined, to a significant extent, by the rewarding value of food (ie, liking and wanting). OBJECTIVE: We determined brain regions involved in liking and wanting and related brain signaling to body mass index (BMI; in kg/m(2)) and dietary restraint. DESIGN: Fifteen normal-weight female subjects [mean ± SEM age: 21.5 ± 0.4 y; BMI: 22.2 ± 0.2] completed a food-choice paradigm by using visually displayed food items during functional magnetic resonance imaging scans. Two scans were made as follows: one scan was made in a fasted condition, and one scan was made in a satiated condition. The paradigm discriminated between liking and wanting, and subjects were offered items rated highly for wanting immediately after each scan. Imaging contrasts for high and low liking and wanting were made, and data for regions of interest were extracted. Activation related to liking and wanting, respectively, was determined. Outcomes were correlated to cognitive dietary restraint and BMI. RESULTS: Dietary restraint predicted liking task-related signaling (TRS) in the amygdala, striatum, thalamus, and cingulate cortex (r = -0.5 ± 0.03, P < 0.00001). In the nucleus accumbens, the premeal liking and wanting TRS and premeal to postmeal liking TRS changes correlated positively with dietary restraint [bilateral average r = 0.6 ± 0.02, P < 0.04 (Bonferroni corrected)]. BMI and hunger predicted wanting TRS in the hypothalamus and striatum (P < 0.05). Postmeal liking TRS in the striatum, anterior insula, and cingulate cortex and wanting TRS in the striatum predicted the energy intake (liking: r = -0.3 ± 0.05, P < 0.0001; wanting: r = -0.3 ± 0.03, P < 0.00001). CONCLUSIONS: Successful dietary restraint was supported by liking TRS from premeal to postmeal in the nucleus accumbens. Reward-related signaling was inversely related to BMI and energy intake, indicating reward deficiency.

Associations between anthropometrical measurements, body composition, single-nucleotide polymorphisms of the hypothalamus/pituitary/adrenal (HPA) axis and HPA axis functioning.

BACKGROUND: The relationship between hypothalamus/pituitary/adrenal (HPA) axis functioning and (visceral) obesity may be explained by single-nucleotide polymorphisms (SNPs) of the HPA axis. Objective To investigate the relationship between the HPA axis SNP's 'BclI' in the glucocorticoid receptor gene and C8246T in the POMC gene and anthropometric measurements, body composition, 5-h cortisol concentrations, HPA axis feedback sensitivity, as well as HPA axis feedback sensitivity under stress in men and women. DESIGN/SUBJECTS/MEASUREMENTS: We assessed in 92 men and 102 women (18-55 years, BMI 19-41 kg/m(2) ) anthropometry, body composition using hydrodensitometry and deuterium dilution method, cortisol variability by measuring 5-h cortisol concentrations, HPA axis feedback functioning using a dexamethasone suppression test and HPA axis functioning under a challenged condition consisting of a standardized high intensity test with ingestion of 4 mg dexamethasone. RESULTS: In female participants, the 8246C allele carriers compared to the 8246T allele carries were associated with a higher 5-h cortisol exposure (1·52 × 10(5) ± 0·8 vs 1·18 × 10(5) ± 0·6 nm·min, P < 0·05) and higher baseline postdexamethasone cortisol concentrations (54·5 ± 35·6 vs 37·4 ± 18·5 nm, P < 0·05). In male participants regarding the C8246T allele carriers and in both male and female participants regarding the BclI genotypes, no significant differences in anthropometric measurements, body composition and HPA axis functioning were observed. Multiple regression analysis showed that only increased 5-h cortisol exposure significantly related to changes in anthropometric measurements and body composition; the BclI and C8246T genotypes were not associated. CONCLUSION: Our preliminary data show that in both men and women (18-55 years, BMI 19-41 kg/m(2) ), the SNP's BclI and C8246T of the HPA axis were primarily related to altered HPA axis functioning, rather than to altered anthropometric measurements and body composition.

A solid high-protein meal evokes stronger hunger suppression than a liquefied high-protein meal.

Hunger is a potential problem for compliance with an energy-restricted diet. Relatively high-protein meal-replacement products have been shown to diminish this problem; they are available as liquid and solid meals, yet their physical state can affect hunger suppression. The objective was to investigate the differences in appetite profile and physiological parameters after consumption of a single-macronutrient, subject-specific, high-protein meal in liquefied vs. solid form, controlled for energy density, weight, and volume. Ten male subjects (age: 21.1 ± 3.9 years; BMI: 22.4 ± 1.2 kg/m²) were offered lunch subject-specifically as 15% of daily energy requirement (DER), consisting of solid (steamed chicken breast + 750 ml water) or liquefied protein (steamed chicken breast blended in 500 ml water + 250 ml water). Appetite profiles, insulin, glucose, and ghrelin were measured over 3 h. Comparing the solid vs. liquefied condition, oral exposure time did not differ between conditions (19.2 ± 0.4 and 18.8 ± 0.6 min, respectively; P = 0.13). Area under the curve (AUC) effects were observed for thirst; statistically significant condition × time interactions and statistically significant differences at several time points were observed for desire to eat (condition × time P < 0.05; 31 ± 6 mm vs. 53 ± 8 mm; P < 0.04 at 115 min) and thirst (condition × time P < 0.01; 27 ± 8 mm vs. 41 ± 8 mm; P < 0.05 at 30 min and 23 ± 6 mm vs. 41 ± 8 mm; P < 0.02 at 70 min) to be lower, while hunger suppression (79 ± 3 mm and 52 ± 10 mm; P < 0.03 at 20 min and 61 ± 7 mm and 44 ± 8 mm; P < 0.03 at 115 min) was higher in the solid condition. Glucose, insulin, and ghrelin concentration curves were similar for both conditions. In conclusion, solid protein evokes a stronger suppression of hunger and desire to eat than liquefied protein.

Effects of single macronutrients on serum cortisol concentrations in normal weight men.

A previous study reported that a high carbohydrate meal, in contrast to a high protein/fat meal, significantly increased cortisol concentrations in visceral obese subjects. The objective of this study was to identify effects of single macronutrients on plasma cortisol concentrations. Ten male subjects (age 27.3±7.4y, BMI 22.1±1.7kg/m(2)) were studied in a randomized crossover design on four days around lunchtime after consuming breakfast matched for daily energy requirements (DER 20%). For lunch they consumed one liter of a shake (DER 18%) containing either fat, protein or carbohydrate, with a raspberry taste and similar hedonic value (59±2mm on a 100mm VAS), using water as control. Serum cortisol concentrations were measured before lunch and during three hours following lunch. Baseline cortisol concentrations did not differ among treatments. The protein as well as the fat lunch caused a significant decrease in cortisol concentrations when compared to the carbohydrate lunch, and showed no difference from the control condition (p<0.05). The cortisol response in the protein condition (AUC=37,024±3518nmol/L min) and in the fat condition (AUC=35,977±3562nmol/L min) were significantly smaller when compared with the cortisol response in the carbohydrate condition (AUC=47,310±3667nmol/L min) (p<0.03), but did not differ from the control condition (AUC=32,784±1683nmol/L min) (Fig. 1). The cortisol response in the carbohydrate condition was significantly higher when compared with the response in the control condition (p<0.004). We conclude that cortisol concentrations decreased after protein or fat intake, which was not different from control; this decrease was prevented by carbohydrate intake.

Genetic associations with acute stress-related changes in eating in the absence of hunger.

BACKGROUND: Acute psychological stress is associated with eating in the absence of hunger. OBJECTIVE: To investigate if BclI and FTO polymorphisms are associated with eating in the absence of hunger as a result of acute psychological stress. METHODS: FTO (rs9939609) and BclI were genotyped in 98 subjects (BMI=23.9+/-3.3kg/m(2)). In a randomized crossover design, the 'eating in absence of hunger' protocol was measured as a function of acute stress vs. a control task and of STAI (State Trait Anxiety Index) state scores. RESULTS: In comparison with the FTO T allele, the A allele was associated with an increased feelings of hunger after food intake in the stress (11+/-10 vs. 18+/-15, p<0.01) and control condition (12+/-9 vs. 16+/-12, p<0.05), even though food intake was not different. For the first time, it was observed that in comparison to the BclI C/C genotype, the BclI G/G genotype was associated with higher STAI states scores at 0, 10, and 20min after the stress condition (30.8+/-6.4 vs. 36.3+/-8.2; 28.3+/-5.5 vs. 32.3+/-7.5; 27.7+/-6.1 vs. 31.2+/-7.5, p<0.05). Additionally, the BclI G/G genotype was associated with a larger difference in energy intake between the stress and control condition, in comparison with the BclI C/C genotype (136.6+/-220.4 vs. 29.4+/-176.3kJ, p<0.04). CONCLUSION: In concordance with previous studies, the FTO A allele is related to a lower feeling of hunger after a standardized meal. For the first time, the BclI G/G genotype is shown to be associated with increased sensitivity to psychological stress, and increased eating in the absence of hunger after stress. PRACTICE IMPLICATIONS: Interventions to reduce body weight should consider the subjects' genetic background.

Hypothalamic-pituitary-adrenal (HPA) axis functioning in relation to body fat distribution.

OBJECTIVE: To relate hypothalamic-pituitary-adrenal (HPA) axis functioning and HPA feedback functioning to body fat distribution in normal weight to obese subjects. PATIENTS: 91 men and 103 women [age 18-45 years, BMI 19-35 kg/m(2), waist-to-hip ratio (WHR) 0.6-1.1]. MEASUREMENTS: Anthropometry, body composition using hydrodensitometry and deuterium dilution method, cortisol variability by measuring 5-h cortisol concentrations, HPA axis feedback functioning using a dexamethasone suppression test, and HPA axis functioning under a challenged condition consisting of a standardized high-intensity test with ingestion of 4 mg dexamethasone. RESULTS: In men, an inverse relationship was observed between 5-h cortisol exposure (nmol/ml) and fat mass index (FMI) (kg/m(2)) (r = -0.55, P < 0.001). In women, relationships were observed between 5-h cortisol exposure (nmol/ml.min) and WHR (r = -0.49, P < 0.001), maximal workload (r = 0.32, P < 0.001) as well as oral contraceptive use (r = 0.38, P < 0.001). Similarly, in men, an inverse relationship was observed between negative feedback expressed as baseline concentrations minus post dexamethasone cortisol concentrations (nmol/ml) and FMI (r = -0.53, P < 0.001). In women, relationships were observed between negative feedback expressed as baseline concentrations minus post dexamethasone cortisol concentrations (nmol/ml) and WHR (r = -0.43, P < 0.001), maximal workload (r = 0.30, P < 0.001) as well as oral contraceptive use (r = 0.43, P < 0.001) in women. Moreover, an inverse relationship was observed between HPA axis functioning in a challenged condition expressed as percentage increase of cortisol concentrations after standardized high-intensity test with ingestion of 4 mg dexamethasone (%) and waist circumference (r = -0.21, P < 0.10) in men and WHR (r = -0.21, P < 0.05) in women. In men, strong positive relationships were observed between FMI and waist circumference (r = 0.85, P < 0.001), as well as waist-to-hip ratio (r = 0.70, P < 0.001). CONCLUSION: Disturbance of HPA axis functioning under basal and challenged conditions is related to visceral fat accumulation.

Eating what you like induces a stronger decrease of 'wanting' to eat.

Human eating behavior may be influenced non-homeostatically by the rewarding value of foods, i.e. 'liking' (pleasure/palatability) and 'wanting' (incentive motivation). The objectives of this study were to validate a computer test for assessment of rewarding value of food, and to assess how rewarding value of food is affected by eating a dessert-specific (chocolate mousse, CM) vs. dessert non-specific, neutral food item (cottage cheese, CC). Seventy-three subjects (47f/26m, age 27.8+/-10.0 y, BMI 24.1+/-3.3 kg/m(2)), studied in a randomized cross-over design, came to the university twice, fasted. A computer test was developed to determine rewarding value, i.e. 'liking' and 'wanting', for 72 items divided in six categories (bread, filling, drinks, dessert, sweets, stationery). 'Liking' was measured by indicating relative preference of paired items (within/between categories), 'wanting' by working to earn items to choose from. Subjects completed the computer test before and after consumption of CM/CC, matched for energy content (5.6 kJ/g) and daily energy requirements (10%). 'Liking' and 'wanting' scores of all fasted subjects on the two test-days showed 62-73% reproducibility. CM was liked more than CC (p<0.001). Consumption of CM decreased 'wanting' for bread, filling, drinks and dessert (p<0.03). Consumption of CC decreased 'wanting' for bread only (p<0.05). Contrary to CC, CM decreased relative 'liking' for the dessert category (p<0.001). In conclusion, the computer test for measurement of 'liking' and 'wanting' is sufficiently valid. Eating a highly liked food item induces a more distinct decrease in 'wanting' for food items in general and category-specific 'liking', than eating a sufficiently liked neutral food item.

Hyperactivity of the HPA axis is related to dietary restraint in normal weight women.

The objective of our study was to investigate the relationship between hypothalamus/pituitary/adrenal (HPA) axis functioning and dietary restraint in normal weight (BMI between 20 and 25 kg/m(2)) men and women. We therefore assessed in 38 men and 38 women HPA axis functioning, through measuring 5-hour cortisol exposure and cortisol feedback functioning through a dexamethasone (4 mg) suppression test. Eating behavior was assessed through the Three Factor Eating Questionnaire and body composition through hydro densitometry and deuterium dilution method. No relationship between HPA axis functioning and dietary restraint was found in men. Normal weight women with a restraint score >/=9 showed increased cortisol concentrations over a 5-hour time period, increased cortisol concentrations after a dexamethasone (4 mg) suppression test, higher BMI, and higher body fat percentage, when compared to women with a restraint score <9. Moreover, a positive relationship was found between cortisol concentrations over a 5-hour time period and dietary restraint in combination with the disinhibition score (R(2)=0.23, p<0.001). We conclude that in normal weight women hyperactivity of the HPA-axis is related to dietary restraint especially in combination with disinhibition.

Acute stress-related changes in eating in the absence of hunger.

Obesity results from chronic deregulation of energy balance, which may in part be caused by stress. Our objective was to investigate the effect of acute and psychological stress on food intake, using the eating in the absence of hunger paradigm, in normal and overweight men and women (while taking dietary restraint and disinhibition into account). In 129 subjects (BMI = 24.5 +/- 3.4 kg/m(2) and age = 27.6 +/- 8.8 years), scores were determined on the Three Factor Eating Questionnaire (dietary restraint = 7.2 +/- 4.4; disinhibition = 4.5 +/- 2.6; feeling of hunger = 3.9 +/- 2.6) and State-Trait Anxiety Inventory (trait score = 31.7 +/- 24.2). In a randomized crossover design, the "eating in absence of hunger" protocol was measured as a function of acute stress vs. a control task and of state anxiety scores. Energy intake from sweet foods (708.1 kJ vs. 599.4 kJ, P < 0.03) and total energy intake (965.2 kJ vs. 793.8 kJ, P < 0.01) were significantly higher in the stress condition compared to the control condition. Differences in energy intake between the stress and control condition were a function of increase in state anxiety scores during the stress task (Delta state anxiety scores) (R(2) = 0.05, P < 0.01). This positive relationship was stronger in subjects with high disinhibition scores (R(2) = 0.12, P < 0.05). Differences in state anxiety scores were a function of trait anxiety scores (R(2) = 0.07, P < 0.05). We conclude that acute psychological stress is associated with eating in the absence of hunger, especially in vulnerable individuals characterized by disinhibited eating behavior and sensitivity to chronic stress.