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.     

Age variations in the relation of body mass indices to estimates of body fat and muscle mass

In some chronic disease studies, distinctions have been made regarding the importance of body mass index (BMI) as a risk factor in younger versus older men and women. In order to determine the significance of these differences in BMI-disease associations, we determined the extent of age-dependent variations in the relation of BMIs to body composition in large probability samples of U.S. men and women from the First and Second U.S. National Health and Nutrition Examination Surveys (NHANES I and II). BMIs are more highly correlated with estimates of body fat in younger than in older men and women, and with muscle mass in older than in younger adults. Caution should be exercised in interpreting the significance of BMI as a risk factor for chronic disease, particularly in comparison of age groups.     

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.     

Moving towards the detection of frailty with biomarkers: A population health study

Aging adults experience increased health vulnerability and compromised abilities to cope with stressors, which are the clinical manifestations of frailty. Frailty is complex, and efforts to identify biomarkers to detect frailty and pre-frailty in the clinical setting are rarely reproduced across cohorts. We developed a predictive model incorporating biological and clinical frailty measures to identify robust biomarkers across data sets. Data were from two large cohorts of older adults: “Invecchiare in Chianti (Aging in Chianti, InCHIANTI Study”) (n = 1453) from two small towns in Tuscany, Italy, and replicated in the Atherosclerosis Risk in Communities Study (ARIC) (n = 6508) from four U.S. communities. A complex systems approach to biomarker selection with a tree-boosting machine learning (ML) technique for supervised learning analysis was used to examine biomarker population differences across both datasets. Our approach compared predictors with robust, pre-frail, and frail participants and examined the ability to detect frailty status by race. Unique biomarker features identified in the InCHIANTI study allowed us to predict frailty with a model accuracy of 0.72 (95% confidence interval (CI) 0.66–0.80). Replication models in ARIC maintained a model accuracy of 0.64 (95% CI 0.66–0.72). Frail and pre-frail Black participant models maintained a lower model accuracy. The predictive panel of biomarkers identified in this study may improve the ability to detect frailty as a complex aging syndrome in the clinical setting. We propose several concrete next steps to keep research moving toward detecting frailty with biomarker-based detection methods.     

Youth BMI Trajectories: Evidence From the NLSY97

We examined heterogeneity in BMI trajectory classes among youth and variables that may be associated with trajectory class membership. We used data from seven rounds (1997–2003) of the 1997 National Longitudinal Survey of Youth (NLSY97), a nationally representative, longitudinal survey of people born between 1980 and 1984 who were living in the United States in 1997. The analyses were based on an accelerated longitudinal design. General growth mixture modeling implemented in Mplus (version 4.1) was used to identify subtypes of youth BMI growth trajectories over time. Four distinct youth BMI trajectories were identified. Class 1 includes youth at high risk for becoming obese by young adulthood (at age 12 and 23, ～67 and 90%, respectively, are classified as obese, and almost 72% will have had a BMI ≥ 40 at some time during this developmental period). Class 2 includes youth at moderate‐to‐high risk (at age 12 and 23, ～55 and 68%, respectively, are classified as obese). Class 3 includes youth at low‐to‐moderate risk (i.e., at age 12 and 23, ～8 and 27%, respectively, are classified as obese). Class 4 includes youth at low risk (few of these youth are obese at any age during this developmental period). These results highlight the importance of considering heterogeneity in BMI growth among youth and early interventions among those most at risk of the adverse health consequences of excess weight.     

Avian forensics: predicting body fat and body mass from wing remains

We describe the development of a method to predict percent body fat of killed birds from the percent fat in the most distal wing tissue, which is often left uneaten by aerial predators. When combined with a measure of body structural size, such as tarsus, culmen or keel length, percent wing fat can be used to predict fresh body mass at the time of death. These techniques may prove useful in field studies of mass-dependent predation risk.     

Sex-specific differences in body condition indices and seasonal mass loss in Tufted Puffins

ABSTRACT.   Reduced prey availability can affect the growth and survival of nestling seabirds. However, few studies have demonstrated similar effects on indices of adult body condition. We examined body condition and seasonal mass loss of breeding adult male and female Tufted Puffins ( Fratercula cirrhata ) at Chiniak Bay, Kodiak Island, Alaska, in 2004–2005. We determined sex using genetic analysis, developed a discriminant function to determine sex using morphometric measurements, and examined the body condition of adult males and females relative to the growth rates of their offspring. We found that morphological measurements were only moderately useful for sexing Tufted Puffins, with 74% of adults ( N = 176) correctly classified. We also found that the relationship between adult body mass and size differed between sexes and conclude that body condition indices must be calculated separately for each sex to avoid inter- and intrasexual bias. Body condition of male and female Tufted Puffins declined during the chick-rearing period. However, body condition of females did not differ between years, whereas male condition declined to a greater degree during 2004 when the mass of young at fledging was significantly lower. Although these results suggest that adult male Tufted Puffins sacrifice their own body condition in years of diminished nestling growth and females do not, reasons for this apparent intersexual difference in reproductive strategies remain unclear.     

Body cell mass: model development and validation at the cellular level of body composition

Existing models to estimate the metabolically active body cell mass (BCM) component in vivo remain incompletely developed. The classic Moore model is based on an assumed BCM potassium content of 120 mmol/kg. Our objectives were to develop an improved total body potassium (TBK)-independent BCM prediction model on the basis of an earlier model (Cohn SH, Vaswani AN, Yasumura S, Yuen K, and Ellis KJ. J Lab Clin Med 105: 305-311, 1985), to apply this improved model in subjects to explore the sex and age dependence of the TBK/BCM ratio, to develop a new TBK/BCM model on the basis of physiological associations between TBK and total body water (TBW) at the cellular level of body composition, and to fit this new model with available reference data. Subjects were 112 healthy adults who had the following components measured: TBW by 2H2O or 3H2O, extracellular water by NaBr, total body nitrogen by in vivo neutron activation, bone mineral by dual-energy X-ray absorptiometry, and TBK by whole body counting. Human reference data were collected from earlier published reports. The improved Cohn model-derived TBK/BCM ratio was (mean +/- SD) 109.0 +/- 10.9 mmol/kg and was not significantly related to sex and age. A simplified version of the new TBK-TBW model provided a TBK/BCM ratio almost identical (109.1 mmol/kg) to that derived by the improved Cohn model. The TBK-BCM prediction formula derived from the improved and new models [BCM (kg) = 1/109 x TBK (mmol); or BCM = 0.0092 x TBK] gives BCM estimates approximately 11% higher than the classic Moore model (BCM = 0.0083 x TBK) formulated on rough tissue composition estimates. The present analyses provide a physiologically based, improved, and validated TBK-BCM prediction formula that should prove useful in body composition and metabolism research.     

Evolution of the cephalopod head complex by assembly of multiple molluscan body parts: Evidence from Nautilus embryonic development

Cephalopod head parts are among the most complex occurring in all invertebrates. Hypotheses for the evolutionary process require a drastic body-plan transition in relation to the life-style changes from benthos to active nekton. Determining these transitions, however, has been elusive because of scarcity of fossil records of soft tissues and lack of some of the early developmental stages of the basal species. Here we report the first embryological evidence in the nautiloid cephalopod Nautilus pompilius for the morphological development of the head complex by a unique assembly of multiple archetypical molluscan body parts. Using a specialized aquarium system, we successfully obtained a series of developmental stages that enabled us to test previous controversial scenarios. Our results demonstrate that the embryonic organs exhibit body plans that are primarily bilateral and antero-posteriorly elongated at stereotyped positions. The distinct cephalic compartment, foot, brain cords, mantle, and shell resemble the body plans of monoplacophorans and basal gastropods. The numerous digital tentacles of Nautilus develop from simple serial and spatially-patterned bud-like anlagen along the anterior-posterior axis, indicating that origins of digital tentacles or arms of all other cephalopods develop not from the head but from the foot. In middle and late embryos, the primary body plans largely change to those of juveniles or adults, and finally form a "head" complex assembled by anlagen of the foot, cephalic hood, collar, hyponome (funnel), and the foot-derived epidermal covers. We suggest that extensions of the collar-funnel compartment and free epidermal folds derived from multiple topological foot regions may play an important role in forming the head complex, which is thought to be an important feature during the body plan transition.     

Sex ratios and mental health: Evidence from China

While sex ratios (i.e., relative numbers of men and women) have been linked to various economic and social outcomes, how sex ratios affect mental health is underexplored. Using nationally representative data from the China Family Panel studies (CFPS) and Population Census, we evaluate the impact of sex ratios on mental health among Chinese men and explore potential mechanisms. Employing the instrumental variables (IV) approach where the One-Child Policy’s mandated fertility limits and implementation are used as exogenous variations in local sex ratios, we find that higher local sex ratios increase depressive symptoms and probability of depression among Chinese men. The impact is stronger for men with lower levels of education and living in rural areas. Analyses of potential mechanisms show that higher sex ratios increase the likelihood of marriage delay and unemployment for men, and prolong working hours for the employed men. The findings are of direct relevance to the health and population policy in China.     

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.     

Estimating fossil hominin body mass from cranial variables: An assessment using CT data from modern humans of known body mass

Body mass estimates are integral to a wide range of inferences in paleoanthropology. Most techniques employ postcranial elements, but predictive equations based on cranial variables have also been developed. Three studies currently provide regression equations for estimating mass from cranial variables, but none of the equations has been tested on samples of known mass. Nor have the equations been compared to each other in terms of performance. Consequently, this study assessed the performance of existing cranial equations using computed tomography scans from a large, documented sample of modern humans of known body mass. Virtual models of the skull were reconstructed and measured using computer software, and the resulting variables were entered into three sets of published regression equations. Estimated and known body masses were then compared. For most equations, prediction errors were high and few individuals were estimated within ±20% of their known mass. Only one equation satisfied the accuracy criteria. In addition, variables that had been previously argued to be good predictors of mass in hominins, including humans, did not estimate mass reliably. These results have important implications for paleoanthropology. In particular, they emphasize the need to develop new equations for estimating fossil hominin body mass from cranial variables. Am J Phys Anthropol 154:201–214, 2014. © 2014 Wiley Periodicals, Inc.     

Analysis of skeletal development on the basis of body mass and bone resorption

Regression analysis was utilized to define the relationships among body weight, whole skeleton bone resorption (3H-tetracycline method), and the development of skeletal mass. The results indicated that skeletal development (% body weight) of slowly growing, 24-week-old rats consisted of two major components, one directly (r = 0.985, P<0.001) and one inversely (r = 0.977, P<0.001) related to body weight. It was further noted that the skeletal resorption rate was inversely correlated to body weight (r = 0.879, P<0.05) and directly related to skeletal development (r = 0.865, P<0.05), suggesting that whole skeleton bone resorption and formation were highly correlated in the slowly growing animal. A third small component of skeletal development identified in the analysis of data from 24-week-old animals, showed no direct relationship to either body weight or resorptive activity. The model presented enables the separation of skeleton mass into major components which may represent mechanically and metabolically driven bone formation.     

Reproduction and longevity among the British peerage: the effect of frailty and health selection

Whether a cost of reproduction exists among humans is still questionable. A major study of aristocratic British families finds a significant positive correlation between parity and late-life mortality, which indicates a trade-off between reproduction and longevity. This result is supported by four other studies, while earlier studies have not found a relationship or came to the opposite conclusion. We show that in natural fertility populations the relationship between fertility and late-life mortality cannot be studied correctly without considering the effects of differences in health and of mortality selection during childbearing ages because these two effects lead to a dampening of the true relationship. If these effects are controlled in Hollingsworth's genealogy of the British peerage a significant trade-off between reproduction and longevity exists for females but not for males.     

Racial differences in body mass indices of men imprisoned in 19th Century Texas

A limited amount of research has been done on the body mass index values of 19th century Americans. This paper uses Texas prison records to demonstrate that, in contrast to today's distributions, most BMI values were in the normal range. Only 21.5% and 1.2% of the population was overweight or obese, while today comparable figures are 36% and 23%. There was also little change in BMI values between 1876 and 1919. Farmers were consistently heavier than non-farmers, while Southwestern men had lower BMI values than their counterparts from other regions of the US. BMI values indicate that 19th century African-Americans, and whites populations were well fed in spite of large expenditures on energy.     

Effect of body weight gain on insulin sensitivity after retirement from exercise training

The objectives of this study were to determine how long increased insulin sensitivity, elicited by exercise training, persists after the end of training and what the effect of weight gain is on this retention. Exercise-trained (ET) rats ran voluntarily in freely rotating wheel cages, and insulin sensitivity was assessed by oral glucose tolerance tests (OGTT) and insulin suppression tests (IST). After training, ET rats were retired for 1, 3, or 7 days (R1, R3, or R7). Initial OGTT and IST studies indicated that sensitivity to insulin-induced glucose uptake was increased in ET rats compared with sedentary control (C) rats and was progressively lost with retirement: ET greater than R1 and R3 greater than R7 and C rats, and this reaction was generally associated with a rapid gain in body weight. Subsequent IST tests were performed on C and R7 rats fed laboratory chow or a hypocaloric diet consisting of equal parts of cellulose and chow for 7 days before the test. The results of these tests showed that steady-state serum glucose (SSSG) levels averaged 165 +/- 12 mg/dl for chow-fed C rats and 172 +/- 11 mg/dl for chow-fed R7 rats that gained body weight at rates twice those of C rats. Chow-fed R7 rats, gaining weight at rates comparable to C rats, had SSSG levels of 104 +/- 6 mg/dl. C and R7 rats fed the hypocaloric diet had SSSG values of 102 +/- 6 and 59 +/- 4 mg/dl, respectively. Muscle glycogen levels were comparable in all groups, and liver glycogen was lower in C and R7 rats fed the hypocaloric diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Taste development from health education among schoolchildren: a two-year intervention study

It is necessary to develop a system of nutritional education which can be understood among schoolchildren who have not yet received a basic education. In the present study, we conducted an educational program for lower-grade schoolchildren, which contained dish selection, an agricultural experience, a cooking experience, and a lecture on digestive absorption. We evaluated the effect of this program on development by measuring taste sensitivity regarding sweet, sour, salty and bitter tastes. For the baseline period, there was no significant difference between the intervention school and the control school in each variable. At follow-up periods, both the intervention and the control schools showed an increasing sense of taste. In the intervention school, development of sensitivity to the sweet, the sour, and the bitter taste was significant. In the control school, development of sensitivity to the sweet and the bitter taste was significant. The increases in the sense of the sour and the bitter tastes and the sum of the four tastes for the intervention subjects were significantly larger than comparable values for the control subjects. These results suggest that the development of taste sensitivity is affected by nutritional education for lower-grade elementary schoolchildren.