Time discounting and the body mass index: Evidence from the Netherlands

In many Western countries, the relative weight of people -- measured by the body mass index (BMI) -- has increased substantially in recent years, leading to an increasing incidence of overweight and related health problems. As with many forms of risky behavior, it is plausible that overweight is related to the individual discount rate. Increases in credit card debts, the rise in gambling and the development of a more hedonic life style, suggest that the average discount rate has increased over time. An increase in time discounting may be a contributing factor in the rise in BMI. Applying a large set of indicators for the individual discount rate from a Dutch survey, this paper analyzes whether changes in time discounting can account for differences in body mass between individuals at a given point in time and whether changes in the average individual discount rate can explain the remarkable increase in BMI experienced in recent years in the Netherlands. We find some evidence for a link between time discounting and differences in BMI between people, but this relationship depends strongly on the choice of the proxy for the discount rate. Giving our hypothesis the best chance, we analyze the development of the time discounting proxies that are most strongly related to BMI. We find no evidence for a change of these proxies over time. Our main conclusion therefore is that overweight might be related to the way people discount future health benefits, but the increase in BMI is more likely explained by shifts in other parameters that determine the intertemporal decisions regarding the trade-off of current and future health and satisfaction.     

A resistin gene polymorphism is associated with body mass index in women

The potential association of resistin (RETN) gene variability with obesity-related phenotypes was investigated in 585 non-diabetic individuals of European descent. The polymorphism studied (–420 C>G) is located in the RETN gene 5-flanking region. A significant association between the polymorphism and body mass index and waist circumference was observed in the women subsample (n=356), where the G allele was somewhat less frequent in the overweight/obese group than in normal-weight individuals (0.25 vs. 0.32; p=0.040; OR=0.70 [0.50–0.98]). Female carriers of the G-allele presented a lower mean BMI than C/C homozygotes (25.5 vs. 26.8 kg/m²; p=0.010). Furthermore, when women were stratified by menopausal status, the association was restricted to premenopausal women (C/C homozygotes, mean BMI=26.3 kg/m²; G-carriers, 24.4 kg/m²; p=0.014). Our findings suggest that RETN gene variation has gender-specific effects on BMI and warrants further investigation of its implications for the development of obesity.     

Diurnal salivary cortisol is associated with body mass index and waist circumference: The multiethnic study of atherosclerosis

Objective:

Neuroendocrine abnormalities, such as activation of the hypothalamic‐pituitary‐adrenal (HPA) axis, are associated with obesity; however, few large‐scale population‐based studies have examined HPA axis and markers of obesity. We examined the cross‐sectional association of the cortisol awakening response (CAR) and diurnal salivary cortisol curve with obesity.

Design and Methods:

The Multiethnic Study of Atherosclerosis Stress Study includes 1,002 White, Hispanic, and Black men and women (mean age 65 ± 9.8 years) who collected up to 18 salivary cortisol samples over 3 days. Cortisol profiles were modeled using regression spline models that incorporated random parameters for subject‐specific effects. Cortisol curve measures included awakening cortisol, CAR (awakening to 30‐min postawakening), early decline (30 min to 2‐h postawakening), late decline (2‐h postawakening to bedtime), and the corresponding areas under the curve (AUC). Body mass index (BMI) and waist circumference (WC) were used to estimate adiposity.

Results:

For the entire cohort, both BMI and WC were negatively correlated with awakening cortisol (P < 0.05), AUC during awakening rise, and early decline and positively correlated to the early decline slope (P < 0.05) after adjustments for age, race/ethnicity, gender, diabetes status, socioeconomic status, β‐blockers, steroids, hormone replacement therapy, and smoking status. No heterogeneities of effects were observed by gender, age, and race/ethnicity.

Conclusions:

Higher BMI and WC are associated with neuroendocrine dysregulation, which is present in a large population sample, and only partially explained by other covariates.     

Moderate‐To‐vigorous physical activity is associated with decreases in body mass index from ages 9 to 15 years

Objective:

The purpose of this study is to determine whether time spent in objectively measured physical activity is associated with change in body mass index (BMI) from ages 9 to 15.

Design and Methods:

The participants were enrolled in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (n = 938). At ages 9, 11, 12, and 15 the time spent in moderate‐to‐vigorous physical activity (MVPA) was objectively measured, and BMI was calculated (kg/m²). Longitudinal quantile regression was used to analyze the data. The 10th, 25th, 50th, 75th, and 90th BMI percentiles were modeled as the dependent variables with age and MVPA (h/day) modeled as predictors. Adjustment was also made for gender, race, sleep, healthy eating score, maternal education, and sedentary behavior.

Results:

A negative association between MVPA and change in BMI was observed at the 90th BMI percentile (?3.57, 95% CI ?5.15 to ?1.99 kg/m² per hour of MVPA). The negative association between time spent in MVPA and change in BMI was progressively weaker toward the 10th BMI percentile (?0.27, 95% CI ?0.62 to 0.07 kg/m² per hour of MVPA). The associations remained similar after adjusting for the covariates, and when the analyses were stratified by gender.

Conclusion:

Time spent in MVPA was negatively associated with change in BMI from age 9 to 15. The association was strongest at the upper tail of the BMI distribution, and increasing time spent in MVPA could help reduce the prevalence of childhood obesity.

     

Interleukin 4 receptor is associated with an increase in body mass index in Koreans

A body of evidence indicates obesity is an inflammatory state with chronic activation of the immune system. The interleukin 4 receptor (IL4R) single nucleotide polymorphism (SNP), rs 180275 (1902A>G) is well recognized for its association with atopy and other inflammatory diseases. We assessed the possible association of rs 180275 and rs 1805010 with obesity in Korean population. Study subject consisting of 876 Koreans were divided into three groups: subjects with 1) BMI<25, 2) BMI between 25 and 27, and 3) BMI>27. Analyses of genotype distributions and allele frequencies of study subjects revealed that rs 180275 polymorphism was associated with an increase in BMI in Korean population (P=0.009 and 0.011, respectively) while no association was found between rs 1805010 and obesity. We observed significantly lower percentage of rs 180275 G allele in subjects with BMI>27 than in subjects with BMI< or =27 (9.9% vs. 16.0%). Logistic regression analysis revealed that the odds ratio (OR) for an increase in BMI associated with the G vs. A allele was 0.57 [95% Confidence interval (CI)=0.39-0.85, p=0.002], which strongly implicates the protective role of rs 180275 G allele against an increase in BMI. Haplotype analysis revealed no association was present between rs 180275 and rs 1805010 polymorphisms. The frequency of rs 180275 G allele is significantly lower in subjects with BMI>27, suggesting the protective role of IL4R rs 180275 G allele against an increase in BMI in Korean population.     

Labor market engagement and the body mass index of working adults: Evidence from India

Galvanized by rapid income growth, labor market transitions in the nature of jobs, and lifestyle factors, there has been an increase in rates of obesity in many developing countries. This paper examines the relationship between BMI and sector and physical intensity of work among urban adults in India. We document that BMI is positively and significantly associated with labor market inactivity. Women in white-collar work have about 1.01 kg/m² higher BMI than women in blue-collar work. For working men, the comparable estimate is approximately 1.18 kg/m². We find that the increase in overall BMI originates from those who are already at high levels of BMI. Further, relative to the non-working sample, employment in a blue-collar occupation is associated with a BMI penalty for men and women. We find suggestive evidence that the increase in BMI for women is driven by a decline in energy expenditure, while both a decrease in energy expenditure and an increase in energy intake are important in explaining BMI dynamics for men. These results are robust to a variety of specification and methodological checks, and suggest that the increasing trend in BMI may be attributed to the transition towards a more sedentary occupational structure. Overall our research underlines the important role played by occupational engagement in determining the general health of populations in developing countries.     

Gestational weight gain and body mass index in children: results from three german cohort studies

Introduction

Previous studies suggested potential priming effects of gestational weight gain (GWG) on offspring’s body composition in later life. However, consistency of these effects in normal weight, overweight and obese mothers is less clear.

Methods

We combined the individual data of three German cohorts and assessed associations of total and excessive GWG (as defined by criteria of the Institute of Medicine) with offspring’s mean body mass index (BMI) standard deviation scores (SDS) and overweight at the age of 5–6 years (total: n = 6,254). Quantile regression was used to examine potentially different effects on different parts of the BMI SDS distribution. All models were adjusted for birth weight, maternal age and maternal smoking during pregnancy and stratified by maternal pre-pregnancy weight status.

Results

In adjusted models, positive associations of total and excessive GWG with mean BMI SDS and overweight were observed only in children of non- overweight mothers. For example, excessive GWG was associated with a mean increase of 0.08 (95% CI: 0.01, 0.15) units of BMI SDS (0.13 (0.02, 0.24) kg/m² of ‘real’ BMI) in children of normal-weight mothers. The effects of total and excessive GWG on BMI SDS increased for higher- BMI children of normal-weight mothers.

Discussion

Increased GWG is likely to be associated with overweight in offspring of non-overweight mothers.     

Helicobacter pylori infection is associated with reduced circulating ghrelin levels independent of body mass index

BACKGROUND: Ghrelin stimulates growth hormone and has orexigenic and adipogenic effects. Plasma ghrelin levels are reduced in obesity and possibly in Helicobacter pylori infection. AIM: To investigate whether there was a relation between H. pylori infection, body mass index (BMI) and serum ghrelin or leptin levels. METHODS: University students undergoing an annual health check-up were invited to participate. H. pylori status was based on the presence of specific IgG H. pylori antibodies in urine. Fasting serum ghrelin, leptin levels, and pepsinogen I and II levels were measured by enzyme immunoassay (EIA). RESULTS: Eight hundred and one students volunteered. There was no significant difference in the height and BMI between those with and without H. pylori infection. The population of ghrelin study consisted of 132 (66 H. pylori-positive and 66 H. pylori-negative) students matched for age, sex, and BMI. The ghrelin level in the H. pylori-positive group was significantly lower (median 55 pmol/l) compared to the H. pylori-negative group (103 pmol/l) (p < .00001). Leptin, triglyceride, total cholesterol, and HDL-cholesterol were not different between the two groups, whereas LDL-cholesterol levels were significantly higher (106 versus 100 mg/dl) (p = .03) in the H. pylori-positive group. Leptin levels correlated with the BMI (r = 0.53) (p < .00001). Among H. pylori-positive subjects, ghrelin correlated only with pepsinogen I levels (r = 0.26, p = .04). CONCLUSIONS: H. pylori infection was associated with a reduction in circulating ghrelin levels independent of sex and BMI.     

Genetic risk sum score comprised of common polygenic variation is associated with body mass index

Genome-wide association studies (GWAS) of body mass index (BMI) using large samples have yielded approximately a dozen robustly associated variants and implicated additional loci. Individually these variants have small effects and in aggregate explain a small proportion of the variance. As a result, replication attempts have limited power to achieve genome-wide significance, even with several thousand subjects. Since there is strong prior evidence for genetic influence on BMI for specific variants, alternative approaches to replication can be applied. Instead of testing individual loci sequentially, a genetic risk sum score (GRSS) summarizing the total number of risk alleles can be tested. In the current study, GRSS comprising 56 top variants catalogued from two large meta-analyses was tested for association with BMI in the Molecular Genetics of Schizophrenia controls (2,653 European-Americans, 973 African-Americans). After accounting for covariates known to influence BMI (ancestry, sex, age), GRSS was highly associated with BMI (p value = 3.19E−06) although explained a limited amount of the variance (0.66%). However, area under receiver operator criteria curve (AUC) estimates indicated that the GRSS and covariates significantly predicted overweight and obesity classification with maximum discriminative ability for predicting class III obesity (AUC = 0.697). The relative contributions of the individual loci to GRSS were examined post hoc and the results were not due to a few highly significant variants, but rather the result of numerous variants of small effect. This study provides evidence of the utility of a GRSS as an alternative approach to replication of common polygenic variation in complex traits.     

LINE-1 methylation is positively associated with healthier lifestyle but inversely related to body fat mass in healthy young individuals

With the goal of investigating if epigenetic biomarkers from white blood cells (WBC) are associated with dietary, anthropometric, metabolic, inflammatory and oxidative stress parameters in young and apparently healthy individuals. We evaluated 156 individuals (91 women, 65 men; age: 23.1±3.5 years; body mass index: 22.0±2.9 kg/m²) for anthropometric, biochemical and clinical markers, including some components of the antioxidant defense system and inflammatory response. DNA methylation of LINE-1, TNF-α and IL-6 and the expression of some genes related to the inflammatory process were analyzed in WBC. Adiposity was lower among individuals with higher LINE-1 methylation. On the contrary, body fat-free mass was higher among those with higher LINE-1 methylation. Individuals with higher LINE-1 methylation had higher daily intakes of calories, iron and riboflavin. However, those individuals who presented lower percentages of LINE-1 methylation reported higher intakes of copper, niacin and thiamin. Interestingly, the group with higher LINE-1 methylation had a lower percentage of current smokers and more individuals practicing sports. On the other hand, TNF-α methylation percentage was negatively associated with waist girth, waist-to-hip ratio and waist-to-stature ratio. Plasma TNF-α levels were lower in those individuals with higher TNF-α methylation. This study suggests that higher levels of LINE-1 and TNF-α methylation are associated with better indicators of adiposity status in healthy young individuals. In addition, energy and micronutrient intake, as well as a healthy lifestyle, may have a role in the regulation of DNA methylation in WBC and the subsequent metabolic changes may affect epigenetic biomarkers.     

Caloric midpoint is associated with total calorie and macronutrient intake and body mass index in undergraduate students

ABSTRACT

Studies have suggested that eating at later times may be a risk factor for being overweight. The aim of this study was to investigate the association of caloric midpoint on the anthropometric profile and calorie and macronutrient intake during the day. The study included 718 Brazilian undergraduate students (20.5 ± 2.9 years old; 67% women). Dietary intake was assessed by 24-h recall and the diurnal variation of calorie consumption was evaluated by caloric midpoint average time at which 50% of daily energy were consumed. Participants were classified into two groups according to caloric midpoint median; early eaters (caloric midpoint ≤ 3:00 pm) or late eaters (caloric midpoint > 3:00 pm). Body weight and waist circumference were measured and body mass index (BMI) was determined. Generalized linear models adjusted for confounding variables were used to determine the association between variables. The late eaters presented higher BMI when compared to early eaters (23.0 kg/m² ± 0.3 vs. 22.1 kg/m² ± 0.2, respectively; p = .02). Late eaters reported a higher total daily consumption of energy (p < .001) and proportion consumed after 9:00 pm (p < .001), as well as total daily carbohydrate (p < .001), protein (p < .001), fat (p < .001), saturated fat (p < .001), and cholesterol (p = .04) intake when compared with early eaters. We conclude that concentrating food intake later in the day is associated with higher total energy and macronutrient intake as well as a higher average BMI.     

Association of elevated body mass index and hypertension with mortality: the CroHort study

Aim of this study was to investigate association of elevated body mass index and hypertension with general mortality in the cohort from Croatian Adult Health Cohort Study (CroHort). Risk of death according to body mass index (BMI) and blood pressure category, in period 2003/08, was calculated for 7,490 respondents, out of which 6,682 were alive and 808 were dead in 2008. Among men aged 65 and more, elevated BMI was associated with lower risk of death, in accordance with obesity paradox recorded in some previous studies which showed that older men with higher BMI have lower risk of death. Among women aged 50-64 years, being hypertensive was associated with increased risk of death compared to normotensive respondents. Despite obesity paradox which should be further explored, activities on primary and secondary prevention of excess weight and hypertension should be encouraged as means to prevent premature mortality in Croatian population.     

The effects of pre-pregnancy body mass index and gestational weight gain on perinatal outcomes in Korean women: a retrospective cohort study

Background  

The purpose of the study was to evaluate the effects of maternal pre-pregnancy body mass index (BMI) and gestational weight gain on perinatal outcomes in a population of Korean women.