Observable Weight Distributions and Children's Individual Weight Assessment

Social networks theory suggests obesity is “contagious” within peer groups in that known friends highly influence weight. On the other hand, an alternative model suggests that observable weight distributions affect perception of one's own obesity level. We examine whether the BMI levels of the most obese classmates in the individual student's grade by gender is positively associated with “under‐assessment” of obesity and overweight (i.e., independently measured obesity or overweight, but subjective self‐assessment of normal weight). The data are the 2004–2005 School Physical Activity and Nutrition III (SPAN), a stratified, multistage probability sample of 4th, 8th, and 11th grade public school children in Texas. We used logistic regression to test whether the gender‐specific 85th percentile BMI level within the individual student's grade at their school is positively associated with “under‐assessment” of obesity and overweight. The results show that students are much more likely to under‐assess their own weight if the gender‐specific 85th percentile BMI level is higher in their grade at their school. These data suggest that observable weight distributions play a key role in the obesity epidemic.     

The Relationship Between Achene Weight,Embryo Weight and Germination inTaraxacumApomicts

Apomicts provide the opportunity to investigate the variation in achene size and performance that is due to factors other than genetic differences between achenes. Achene characteristics of a single capitulum from each of 15 biotypes of apomicticTaraxacumwere investigated. Within a capitulum, achene fresh weight ranged from 4.45-fold to 13.74-fold. Overall, 59.8% of achenes germinated. The probability of any one achene germinating was influenced both by its source and by its weight and ranged from 0.049 to 0.902 between capitula and from 0.028 to 0.873 between weight classes. An investigation of the relationship between achene parts in three biotypes identified a linear trend for embryos to acquire a greater proportion of total achene weight as achene weight increases. Although the heaviest achenes showed the best germination, it is predicted that, for a given investment of maternal resources, seedling number would be maximized by producing achenes of a single intermediate weight.     

Pregnancy Weight Gain and Childhood Body Weight: A Within-Family Comparison

Background

Excessive pregnancy weight gain is associated with obesity in the offspring, but this relationship may be confounded by genetic and other shared influences. We aimed to examine the association of pregnancy weight gain with body mass index (BMI) in the offspring, using a within-family design to minimize confounding.

Methods and Findings

In this population-based cohort study, we matched records of all live births in Arkansas with state-mandated data on childhood BMI collected in public schools (from August 18, 2003 to June 2, 2011). The cohort included 42,133 women who had more than one singleton pregnancy and their 91,045 offspring. We examined how differences in weight gain that occurred during two or more pregnancies for each woman predicted her children''s BMI and odds ratio (OR) of being overweight or obese (BMI≥85th percentile) at a mean age of 11.9 years, using a within-family design. For every additional kg of pregnancy weight gain, childhood BMI increased by 0.0220 (95% CI 0.0134–0.0306, p<0.0001) and the OR of overweight/obesity increased by 1.007 (CI 1.003–1.012, p = 0.0008). Variations in pregnancy weight gain accounted for a 0.43 kg/m² difference in childhood BMI. After adjustment for birth weight, the association of pregnancy weight gain with childhood BMI was attenuated but remained statistically significant (0.0143 kg/m² per kg of pregnancy weight gain, CI 0.0057–0.0229, p = 0.0007).

Conclusions

High pregnancy weight gain is associated with increased body weight of the offspring in childhood, and this effect is only partially mediated through higher birth weight. Translation of these findings to public health obesity prevention requires additional study. Please see later in the article for the Editors'' Summary     

封闭群五指山小型猪主要脏器重量与体重的相关性分析

目的测定封闭群五指山小型猪主要脏器重量和脏器系数,对脏器重量与体重的相关性进行分析,并计算出相应的直线回归方程和多元回归方程。方法实验选用6-10月龄普通级封闭群五指山小型猪30头（其中♂16头、♀14头）,分别测定体重和7个主要脏器重量,计算脏器系数,通过SAS软件进行脏器系数的性别间比较和各脏器重与体重间的相关与回归分析。结果性别间比较,小型猪仅有心脏的脏器系数差异有显著性（P〈0.05）。除公猪的胃脏和母猪的肺脏外,所测脏器重量与体重间均有明显的正相关线性关系;多因素分析显示公猪的肝脏和肾脏,母猪的心脏、肝脏和肾脏对各自体重有影响。结论封闭群五指山小型猪主要脏器系数性别间差异较小,其体重与某些脏器重量存在一定的线性关系。     

Weight Regain Following Sustained Weight Reduction is Predicted by Relative Insulin Sensitivity

YOST, TRUDY J, DALAN R JENSEN AND ROBERT H ECKEL. Weight regain following sustained weight reduction is predicted by relative insulin sensitivity. Obes Res. Ten moderately obese women (body mass index 34.9 ± 1.1 kg/m² mean ± SEM), had previously been through a 3-month weight loss program followed by 3 months of weight maintenance at the reduced weight. A euglycemic clamp for determination of insulin sensitivity was performed on each subject prior to weight loss, and another at the end of the weight maintenance phase. The mean weight loss for the group was 11.4 ± 2.2 kg. The women were then seen for follow-up weights 12 months and 18 months after the conclusion of the weight maintenance period. All of the women except one had regained their weight by the time of the 12-month visit. It was found that the amount of weight regained both at 12 months and 18 months was correlated with the change in insulin sensitivity which occurred from the baseline study to after weight loss/maintenance. The data indicate that increased insulin sensitivity following sustained weight loss in obese women predicts weight regain.     

Reductions in Internal Disinhibition During Weight Loss Predict Better Weight Loss Maintenance

The construct of disinhibition, as measured by the Eating Inventory, was recently found to have two factors: internal disinhibition (eating in response to cognitive and emotional cues) and external disinhibition (eating in response to environmental cues). This study examined whether early changes in disinhibition that occurred during a weight loss program predicted later weight loss maintenance. Participants were adults enrolled in a weight loss treatment study (n = 81, 16% men, BMI = 38.4 ± 6.5 kg/m²). Two‐thirds of participants were African Americans. Participants received a uniform, meal‐replacement‐based weight loss program in months 1–3 and one of four nutritionally focused programs for weight loss maintenance in months 4–12. Disinhibition and weight were assessed at clinic visits. Change in internal disinhibition from months 1–3 (i.e., the weight loss period) significantly predicted change in weight from month 4 to 12 (i.e., the weight maintenance period); this remained significant when treatment group, age, gender, ethnicity, baseline weight, baseline depression, baseline internal disinhibition, and initial weight loss were controlled for (P = 0.03). A comparable analysis examining change in external disinhibition found that it was not a significant predictor of weight maintenance (P = 0.43). Participants who experienced the biggest decreases in internal disinhibition during the initial phase of treatment had the most success maintaining their weight loss in the next phase of treatment. Long‐term weight loss outcomes may be improved by spending sufficient treatment time teaching strategies for reducing eating in response to internal cues.