Short sleep duration is associated with a lower mean satiety quotient in overweight and obese men.

We examined satiety quotient (SQ) and energy intake (EI) according to sleep duration, quality and timing. Seventy-five overweight/obese men (age: 41.1±5.8 years; body mass index: 33.6±2.9 kg/m(2)) completed visual analogue scales for appetite sensations before, immediately after and every 10 minutes for 1 hour following a standardized breakfast. The mean SQ (primary outcome of the study) was calculated from four appetite sensations. The Pittsburgh Sleep Quality Index identified short-duration (<7 h/night) and 'recommended sleep duration' (7 h/night) sleepers, poor (score 5)- and good (score <5)-quality sleepers and late (midpoint of sleep >0230 hours) and early (midpoint of sleep 0230 hours) sleepers. A 3-day food record and buffet-style meal assessed the EI. Short-duration sleepers had a lower mean SQ compared with recommended sleep duration sleepers (6.5±4.9 vs 8.8±4.3 mm/100 kcal; P=0.04). The mean SQ between poor and good (6.9±4.6 vs 8.7±4.6 mm/100 kcal; P=0.11) and that between early and late (8.99±5.10 vs 9.32±4.02 mm/100 kcal; P=0.78) sleepers were not significantly different. EI did not differ between the sleep groups. Thus, short-duration sleepers had a lower mean SQ compared with recommended sleep duration sleepers. However, this did not coincide with an increased EI.

Behavioural and metabolic characterisation of the low satiety phenotype.

Some individuals report weak appetite sensations and thus, have higher susceptibility to overeating. The aim of this study was (1) to evaluate the reliability of the satiety quotient (SQ), a marker of satiety efficiency; (2) to characterize the biopsychobehavioural profiles of individual presenting low satiety efficiency, i.e. the low satiety phenotype and (3) to document the impact of a weight loss program on these profiles. Sixty-nine obese men (BMI 33.6±3.0 kg/m², age 41.5±5.7 years) participated in a 16-week, non-restrictive weight loss intervention. Visual analog scales for appetite sensations in response to a test-meal were completed twice at baseline. Blood samples were collected before and during one test-meal. Questionnaires were administered before and after the intervention. The mean SQ showed good reliability (ICC=0.67). Baseline SQ scores tended to be negatively correlated with external hunger, anxiety and night eating symptoms (p<0.10). Moreover, the low satiety phenotype showed a lower cortisol response to the test-meal (p<0.05). The SQ seems to be a reliable marker of weaker appetite sensation responses. Stress/anxiety could be involved in the low satiety phenotype but did not influence the biopsychobehavioural changes in response to the intervention.

Parental eating behavior traits are related to offspring BMI in the Québec Family Study.

OBJECTIVE: Parental eating behavior traits have been shown to be related to the adiposity of their young children. It is unknown whether this relationship persists in older offspring or whether rigid or flexible control are involved. The objective of this study was to test the hypothesis that parental eating behavior traits, as measured by the Three-Factor Eating Questionnaire (TFEQ), are related to offspring body weight. METHODS: Cross-sectional anthropometric and TFEQ data from phase 2 and 3 of the Québec Family Study generated 192 parent-offspring dyads (offspring age range: 10-37 years). Relationships were adjusted for offspring age, sex and reported physical activity, number of offspring per family and parent body mass index (BMI). RESULTS: In all parent-offspring dyads, parental rigid control and disinhibition scores were positively related to offspring BMI (r=0.17, P=0.02; r=0.18, P<0.01, respectively). There were no significant relationships between cognitive restraint (P=0.75) or flexible control (P=0.06) with offspring BMI. Regression models revealed that parent disinhibition mediated the relationship between parent and offspring BMI, whereas rigid control of the parent moderated this relationship. The interaction effect between parental rigid control and disinhibition was a significant predictor of offspring BMI (ß=0.13, P=0.05). CONCLUSION: Family environmental factors, such as parental eating behavior traits, are related to BMI of older offspring, and should be a focus in the prevention of obesity transmission within families.

The night-eating syndrome and obesity.

The rising prevalence of obesity is a global concern. Eating behaviour and circadian rhythm are proving to be important factors in the aetiology of obesity. The night-eating syndrome (NES) is characterized by increased late-night eating, insomnia, a depressed mood and distress. It is evident that prevalence is higher among weight-related populations than the general community. The exact relationship between this syndrome and obesity remains unclear. The reasons for the discrepancies found in the literature likely include varying diagnostic criteria and a wide range of study population characteristics. NES does not always lead to weight gain in thus certain individuals may be susceptible to night-eating-related weight gain. Weight loss through surgical and behavioural treatments has shown success in diminishing symptoms. The increasing literature associating obesity with circadian imbalances strengthens the link between the NES and obesity. Circadian genes may play a role in this syndrome. This review will examine different aspects of obesity in the context of the NES.

The Three-Factor Eating Questionnaire and BMI in adolescents: results from the Québec family study.

Eating behaviour traits are associated with body weight variations in adults. The Three-Factor Eating Questionnaire (TFEQ) measures cognitive restraint, disinhibition and hunger, as well as their corresponding subscales, e.g. rigid and flexible control. The TFEQ has not been widely used in adolescents to investigate eating behaviour traits associated with body weight. The aim of the present study was to assess whether eating behaviour traits were associated with BMI in male and female adolescents. Sixty adolescents (thirty females and thirty males; mean age 15.0 (sd 2.4) years) from the Québec Family Study completed the TFEQ and 3 d dietary records. There were no sex differences in the TFEQ scores. Rigid control, disinhibition and emotional susceptibility (to overeat) were positively related to BMI z-scores for the entire sample (r 0.3, P < 0.05). There was a positive relationship between BMI z-scores and rigid control (r 0.39, P < 0.05) in females, while BMI z-scores were positively related to emotional susceptibility (r 0.42, P < 0.02) and disinhibition (r 0.41, P < 0.03) in males. Adolescents characterised by both high disinhibition and high rigid control had significantly higher BMI z-scores than those by both low disinhibition and low rigid control. There were no significant differences in BMI z-scores between the flexible control categories. Dietary macronutrient content was not consistently related to eating behaviour traits. These results show that the eating behaviour traits of disinhibition and rigid control are independently related to BMI z-scores in this group of adolescents.

Noise and nonlinearity in measles epidemics: combining mechanistic and statistical approaches to population modeling.

We present and evaluate an approach to analyzing population dynamics data using semimechanistic models. These models incorporate reliable information on population structure and underlying dynamic mechanisms but use nonparametric surface-fitting methods to avoid unsupported assumptions about the precise form of rate equations. Using historical data on measles epidemics as a case study, we show how this approach can lead to better forecasts, better characterizations of the dynamics, and a better understanding of the factors causing complex population dynamics relative to either mechanistic models or purely descriptive statistical time-series models. The semimechanistic models are found to have better forecasting accuracy than either of the model types used in previous analyses when tested on data not used to fit the models. The dynamics are characterized as being both nonlinear and noisy, and the global dynamics are clustered very tightly near the border of stability (dominant Lyapunov exponent lambda approximately 0). However, locally in state space the dynamics oscillate between strong short-term stability and strong short-term chaos (i.e., between negative and positive local Lyapunov exponents). There is statistically significant evidence for short-term chaos in all data sets examined. Thus the nonlinearity in these systems is characterized by the variance over state space in local measures of chaos versus stability rather than a single summary measure of the overall dynamics as either chaotic or nonchaotic.

Smooth nonparametric maximum likelihood estimation for population pharmacokinetics, with application to quinidine.

The seminonparametric (SNP) method, popular in the econometrics literature, is proposed for use in population pharmacokinetic analysis. For data that can be described by the nonlinear mixed effects model, the method produces smooth nonparametric estimates of the entire random effects density and simultaneous estimates of fixed effects by maximum likelihood. A graphical model-building strategy based on the SNP method is described. The methods are illustrated by a population analysis of plasma levels in 136 patients undergoing oral quinidine therapy.