Zhihao Zhang et al.
Current Biology, forthcoming
Obesity is a major epidemic in many parts of the world. One of the main factors contributing to obesity is overconsumption of high-fat and high-calorie food, which is driven by the rewarding properties of these types of food. Previous studies have suggested that dysfunction in reward circuits may be associated with overeating and obesity. The nature of this dysfunction, however, is still unknown. Here, we demonstrate impairment in reward-based associative learning specific to food in obese women. Normal-weight and obese participants performed an appetitive reversal learning task in which they had to learn and modify cue-reward associations. To test whether any learning deficits were specific to food reward or were more general, we used a between-subject design in which half of the participants received food reward and the other half received money reward. Our results reveal a marked difference in associative learning between normal-weight and obese women when food was used as reward. Importantly, no learning deficits were observed with money reward. Multiple regression analyses also established a robust negative association between body mass index and learning performance in the food domain in female participants. Interestingly, such impairment was not observed in obese men. These findings suggest that obesity may be linked to impaired reward-based associative learning and that this impairment may be specific to the food domain.
Ilan Dar-Nimrod et al.
Appetite, October 2014, Pages 269–276
Public discourse on genetic predispositions for obesity has flourished in recent decades. In three studies, we investigated behaviorally-relevant correlates and consequences of a perceived genetic etiology for obesity. In Study 1, beliefs about etiological explanations for obesity were assessed. Stronger endorsement of genetic etiology was predictive of a belief that obese people have no control over their weight. In Study 2, beliefs about weight and its causes were assessed following a manipulation of the perceived underlying cause. Compared with a genetic attribution, a non-genetic physiological attribution led to increased perception of control over one's weight. In Study 3, participants read a fictional media report presenting either a genetic explanation, a psychosocial explanation, or no explanation (control) for obesity. Results indicated that participants who read the genetic explanation ate significantly more on a follow-up task. Taken together, these studies demonstrate potential effects of genetic attributions for obesity.
Po Lai Yau et al.
Obesity, August 2014, Pages 1865–1871
Objective: To ascertain whether pediatric obesity without clinically significant insulin resistance (IR) impacts brain structure and function.
Methods: Thirty obese and 30 matched lean adolescents, all without clinically significant IR or a diagnosis of metabolic syndrome (MetS), received comprehensive endocrine, neuropsychological, and MRI evaluations.
Results: Relative to lean adolescents, obese non-IR adolescents had significantly lower academic achievement (i.e., arithmetic and spelling) and tended to score lower on working memory, attention, psychomotor efficiency, and mental flexibility. In line with our prior work on adolescent MetS, memory was unaffected in uncomplicated obesity. Reductions in the thickness of the orbitofrontal and anterior cingulate cortices as well as reductions of microstructural integrity in major white matter tracts without gross volume changes were also uncovered.
Conclusions: It was documented, for the first time, that adolescents with uncomplicated obesity already have subtle brain alterations and lower performance in selective cognitive domains. When interpreting these preliminary data in the context of our prior reports of similar, but more extensive brain findings in obese adolescents with MetS and T2DM, it was concluded that “uncomplicated” obesity may also result in subtle brain alterations, suggesting a possible dose effect with more severe metabolic dysregulation giving rise to greater abnormalities.
Blair Kidwell, Jonathan Hasford & David Hardesty
Journal of Marketing Research, forthcoming
Consumers are often mindless eaters (Wansink 2006). The current research provides a framework for how consumers can become more mindful of their food choices. An ability-based training program is developed to strengthen individuals' ability to focus on goal-relevant emotional information. We not only demonstrate that emotional ability is trainable and that food choices can be enhanced (study 1), but also that emotional ability training improves food choices beyond a nutrition knowledge training program (study 2). Then, in study 3, a test of our conceptual model indicated that emotional ability training increased goal-relevant emotional thoughts and reduced reliance on the unhealthy=tasty intuition. Both of these factors mediated mindful eating effects. Lastly, in study 4 the long-term benefits of emotional ability training were demonstrated by showing that emotionally trained individuals lost weight over a 3-month period relative to a control group and nutrition knowledge training group. Together, these findings suggest that consumers can gain control over their food choices through enhancement of emotional ability. Implications for policy officials, health care professionals, and marketers are discussed.
Carolina Werle, Brian Wansink & Collin Payne
Marketing Letters, forthcoming
Do consumers eat more when they exercise more? If so, the implications could ripple through the multi-billion dollar fitness and food industries and have implications for both consumers and health-care providers. Three studies — two field experiments and one observational field study — triangulate on this potential compensatory mechanism between physical activity and food intake. The findings showed that when physical activity was perceived as fun (e.g., when it is labeled as a scenic walk rather than an exercise walk), people subsequently consume less dessert at mealtime and consume fewer hedonic snacks. A final observational field study during a competitive race showed that the more fun people rated the race as being, the less likely they were to compensate with a hedonic snack afterwards. Engaging in a physical activity seems to trigger the search for reward when individuals perceive it as exercise but not when they perceive it as fun. Key implications for the fitness industry and for health-care professionals are detailed along with the simple advice to consumers to make certain they make their physical activity routine fun in order to avoid compensation.
Jessica Jones-Smith et al.
PLoS ONE, June 2014
Objective: Our objective was to use longitudinal data from a US birth cohort to test whether the probability of overweight or obesity during the first 6 years of life varied according to socioeconomic status.
Design and Methods: Using six waves of longitudinal data from full-term children in the Early Childhood Longitudinal Study-Birth Cohort (2001–2007; n≈4,950), we examined the prevalence of overweight or obesity (Body Mass Index (BMI)>2 standard deviations above age- and sex- specific WHO Childhood Growth Standard reference mean; henceforth, “overweight/obesity”) according to age, socioeconomic status, and race/ethnicity using generalized estimating equation models.
Results: The association between socioeconomic status and overweight/obesity varied significantly by race/ethnicity, but not by sex. Overweight/obesity was significantly associated with socioeconomic status among whites, Hispanics and Asians; the adjusted odds of overweight/obesity began to diverge according to SES after the first 9 months of life. By approximately 4 years, children with the highest SES had a significantly lower odds of overweight/obesity. SES was not significantly related to overweight/obesity among African Americans and American Indians during early childhood.
Conclusions: Few studies have assessed the associations between SES and overweight/obesity within racial/ethnic groups in the US. We find that in contemporary, US-born children, SES was inversely associated with overweight/obesity among more racial/ethnic groups (whites, Hispanics, and Asians) than previously reported.
Pia Chaparro et al.
Journal of Epidemiology & Community Health, forthcoming
Background: Few studies have examined the association between the food environment and adiposity in early childhood, a critical time for obesity prevention. The objective of this study was to examine the longitudinal association between neighbourhood food environment and adiposity among low-income preschool-aged children in a major metropolitan region in the USA.
Methods: The study sample was 32 172 low-income preschool-aged children in Los Angeles County who had repeated weight and height measurements collected between ages 2 and 5 years through a federal nutrition assistance programme. We conducted multilevel longitudinal analyses to examine how spatial densities of healthy and unhealthy retail food outlets in the children's neighbourhoods were related to adiposity, as measured by weight-for-height z-score (WHZ), while controlling for neighbourhood-level income and education, family income, maternal education, and child's gender and race/ethnicity.
Results: Density of healthy food outlets was associated with mean WHZ at age 3 in a non-linear fashion, with mean WHZ being lowest for those exposed to approximately 0.7 healthy food outlets per square mile and higher for lesser and greater densities. Density of unhealthy food outlets was not associated with child WHZ.
Conclusions: We found a non-linear relationship between WHZ and density of healthy food outlets. Research aiming to understand the sociobehavioural mechanisms by which the retail food environment influences early childhood obesity development is complex and must consider contextual settings.
Bo Xi et al.
Objectives: Previous studies showed that prevalence of abdominal obesity among US children and adolescents increased significantly between 1988–1994 and 2003–2004. However, little is known about recent time trends in abdominal obesity since 2003–2004.This study was to provide recent updated national estimates of childhood abdominal obesity and examine the trends in childhood abdominal obesity from 2003 to 2012.
Methods: Data were from the National Health and Nutrition Examination Survey (NHANES) conducted during 5 time periods (2003–2004, 2005–2006, 2007–2008, 2009–2010, and 2011–2012). A total of 16 601 US children and adolescents aged 2 to 18 years were included. Abdominal obesity is defined as a waist circumference (WC) ≥ gender- and age-specific 90th percentile based on data from NHANES III (1988–1994) and a waist-to-height (WHtR) ≥0.5, respectively.
Results: In 2011–2012, 17.95% of children and adolescents aged 2 to 18 years were abdominally obese defined by WC, and 32.93% of those aged 6 to 18 years were abdominally obese defined by WHtR. Mean WC and WHtR and prevalence of abdominal obesity kept stable between 2003–2004 and 2011–2012, independently of gender, age, and race/ethnicity. However, there was a significant decrease in abdominal obesity among children aged 2 to 5 years.
Conclusions: The prevalence of abdominal obesity leveled off among US children and adolescents from 2003–2004 to 2011–2012.
Uri Ladabaum et al.
American Journal of Medicine, forthcoming
Background: Obesity and abdominal obesity are independently associated with morbidity and mortality. Physical activity attenuates these risks. We examined trends in obesity, abdominal obesity, physical activity, and caloric intake in U.S. adults from 1988 to 2010.
Methods: Univariate and multivariate analyses were performed using National Health and Nutrition Examination Survey (NHANES) data.
Results: Average body-mass index (BMI) increased by 0.37% (95% CI, 0.30-0.44%) per year in both women and men. Average waist circumference increased by 0.37% (95% CI, 0.30-0.43%) and 0.27% (95% CI, 0.22-0.32%) per year in women and men, respectively. The prevalence of obesity and abdominal obesity increased substantially, as did the prevalence of abdominal obesity among overweight adults. Younger women experienced the greatest increases. The proportion of adults who reported no leisure-time physical activity increased from 19.1% (95% CI, 17.3-21.0%) to 51.7% (95% CI, 48.9-54.5%) in women, and from 11.4% (95% CI, 10.0-12.8%) to 43.5% (95% CI, 40.7-46.3%) in men. Average daily caloric intake did not change significantly. BMI and waist circumference trends were associated with physical activity level, but not caloric intake. The associated changes in adjusted BMIs were 8.3% (95% CI, 6.9-9.6%) higher among women and 1.7% (95% CI, 0.68-2.8%) higher among men with no leisure-time physical activity compared to those with an ideal level of leisure-time physical activity.
Conclusions: Our analyses highlight important dimensions of the public health problem of obesity, including trends in younger women and in abdominal obesity, and lend support to the emphasis placed on physical activity by the Institute of Medicine.
Bettina Cornwell, Anna McAlister & Nancy Polmear-Swendris
Appetite, October 2014, Pages 277–283
Studies regarding the advancing challenges of obesity in many countries are beginning to converge on the importance of early food exposure and consumption patterns. Across two studies (Study 1, 34 boys, 35 girls; Study 2, 40 boys, 35 girls, ages 3–6), child knowledge of brands offering products high in sugar, salt and fat was shown to be a significant predictor of child BMI, even after controlling for their age and gender and when also considering the extent of their TV viewing. Additionally, two different collage measures of brand knowledge (utilized across the two studies) performed similarly, suggesting that this measure may be serving as a surrogate indicator of an overall pattern of product exposure and consumption. Policy implications are discussed.
Jill Holm-Denoma et al.
Journal of Health Psychology, June 2014, Pages 754-764
Little is known about the psychosocial circumstances under which children develop excessive body mass. A community sample was followed up from age 2–10 years to determine which early problems were predictive of increased body mass index. Hypothesized mediators (i.e. eating habits, physical activity, and “screen time”) were also examined. After controlling for parental psychopathology, family income, child’s gender, and child’s body mass index, externalizing behaviors, aggressive behaviors, and anger predicted a relatively high body mass index. Exploratory analyses did not support hypothesized mediators, although low power was an issue.
Sergey Melnikov et al.
Objective: Simple aeration of food matrices with gas has previously been shown to generate immediate suppression of appetite, though duration of effects has not been shown. This research tested whether liquids aerated with nitrous oxide (N2O) to achieve high in-body stability could produce enhanced and sustained effects on eating motivations.
Methods: In two randomized cross-over studies, appetite ratings were collected for 240 min. In Study 1, 24 volunteers consumed a full portion liquid (325 ml, 190 kcal) or aerated (1,000 ml, 190 kcal) drink at 0 min, or half portions of liquid (162 ml, 95 kcal) or aerated (500 ml, 95 kcal) drink at 0 and 120 min. In Study 2, assessing the effect of N2O itself, 23 volunteers consumed water saturated with N2O or with CO2 10 min after a mini-drink (180 kcal). Appetite was quantified by area-under-the curve (AUC) and time-to-return-to-baseline (TTRTB).
Results: Full- and half-size aerated drinks decreased hunger AUC over 4 h by 26 and 50% (P < 0.0001) versus the respective liquid versions. Effects were also sustained significantly longer (TTRTB from 203 to 335 and from 173 to 286 min, respectively). In Study 2, N2O and CO2 had similar effects on appetite ratings.
Conclusions: Aeration of foods using appropriate microstructural design has a powerful effect on eating motivations.
Beate Herbert & Olga Pollatos
Eating Behaviors, August 2014, Pages 445–448
Objective: Perceiving internal signals of hunger and satiety are related to the regulation of food intake. Recent data suggest that interoception (perception of bodily signals) and interoceptive sensitivity (sensitivity for internal signals) might be a crucial variable for the regulation of behavior associated with feelings of satiety. It is yet unclear whether interoceptive sensitivity is altered in overweight and obese participants.
Design and methods: We therefore examined interoceptive sensitivity among 75 overweight and obese women and men using a heartbeat detection task and compared them to normal weight controls. We hypothesized that overweight and obesity would be related to attenuated interoceptive sensitivity.
Results: Interoceptive sensitivity was higher in normal weight participants as compared to overweight and obese participants. Additionally, we found a negative correlation coefficient between the BMI and interoceptive sensitivity in the overweight and obese group only.
Conclusions: In accordance with our hypotheses, we found evidence for reduced interoceptive sensitivity in overweight and obese individuals. Interoceptive sensitivity presumably interacts with regulation of food intake in everyday life in part by facilitating the detection of bodily changes accompanying satiety. Overweight and obese individuals might experience greater difficulties in accurately detecting such signals due to reduced interoceptive sensitivity.
Qi Zhang et al.
Journal of Epidemiology & Community Health, forthcoming
Background: Clustered obese parents and children are prevalent, but there is little knowledge about whether and how child–parent resemblance varies by sociodemographic groups.
Methods: This paper used nationally representative data from the National Health and Nutrition Examination Survey III (NHANES: 1988–1994). We matched 4958 parents with 6765 children aged 2–16 years old for whom we had complete data on body mass index (BMI), overweight and obesity status. Correlation coefficients and κ statistics between parents’ and children's BMI and body weight status were calculated for different sociodemographic groups. Multivariate linear and logistic regression models were fit to study the child–parent resemblance and socioeconomic and demographic differences in the resemblance.
Results: The child–parent correlation coefficients for BMI were greater in Caucasians than in minorities and greater in groups with higher socioeconomic status. The mother–child resemblance in BMI was negatively associated with child age (p<0.001). The mother–daughter resemblance in overweight was significantly lower in non-Hispanic blacks (OR=0.53, 95% CI (0.36 to 0.78)) and Mexican Americans (OR=0.58, 95% CI (0.36 to 0.93)) than in Caucasians. The father–child resemblance in overweight was significantly lower in high school graduates compared with those with less-than-high-school-graduate fathers (OR=0.53, 95% CI (0.37 to 0.77) for father–son dyads and OR=0.69, 95% CI (0.50 to 0.96) for father–daughter dyads). Similar results were found for parent–child resemblance in obesity.
Conclusions: Child–parent resemblance in body weight status exists across sociodemographic groups in the USA, but it varies by demographics and socioeconomic status.
Laura Miller et al.
American Journal of Health Promotion, July/August 2014, Pages e137-e145
Purpose: Examine whether individual-level childhood obesity is related to residential availability of fast food and healthy food outlets.
Subjects: A total of 1850 children aged 5 to 15 years in 2005–2010 who participated in the Western Australian Health and Wellbeing Surveillance System survey.
Results: An increasing number of healthy food outlets within 800 m of a child's home was associated with a significantly reduced risk of being overweight/obese in all models tested. After controlling for age, physical activity, time spent sedentary, weekly takeaway consumption, area disadvantage, and count of fast food outlets, each additional healthy food outlet within 800 m was associated with a 20% decrease in the likelihood of a child being overweight or obese (odds ratio: .800, 95% confidence intervals: .686–.933).
Conclusion: The local food environment around children's homes has an independent effect on child weight status. These findings highlight the importance of the built environment as a potential contributor towards child health, which should be considered when developing community health promotion programs.
Zeljko Pedisic et al.
Objective: Evidence on the direction of the association between sitting time and obesity is limited. The prospective associations between baseline total sitting time and subsequent changes in body mass index (BMI), and baseline BMI and subsequent changes in sitting time were examined.
Methods: BMI, from self-reported height and weight, and a single-item measure of sitting time were ascertained at two time points (3.4 ± 0.96 years apart) in a prospective questionnaire-based cohort of 31,787 Australians aged 45–65 years without severe physical limitations.
Results: In a fully adjusted model, baseline obesity was associated with increased sitting time among all participants (adjusted odds ratio [aOR] = 1.20 [95% CI, 1.11-1.30]; P < 0.001) and in most subgroups. The association was significant among those who were sitting <4 hours/day (aOR = 1.24 [95% CI, 1.07-1.44]; P = 0.004) and 4–8 hours/day at baseline (aOR=1.18 [95% CI, 1.06-1.32]; P = 0.003), but not in the high sitting groups (P = 0.111 and 0.188 for 8–11 and ≥11 sitting hours/day, respectively). Nonsignificant and inconsistent results were observed for the association between baseline sitting time and subsequent change in BMI.
Conclusions: Our findings support the hypothesis that obesity may lead to a subsequent increase in total sitting time, but the association in the other direction is unclear.