Child-to-adult body mass index and height trajectories: a comparison of 2 British birth cohorts

Association of Weight Trajectory With Severe Obesity: A Case-Control Study

Background: Early childhood weight trajectory is associated with future risk for obesity. However, little is known about the association of birth weight and weight trajectories before age 5.5 years with severe adult obesity. Methods: This study used a nested case-control design of 785 matched sets of cases and controls matched 1:1 on age and gender from a 1976 to 1982 birth cohort in Olmsted County, Minnesota. Cases with severe adult obesity were defined as individuals with a BMI ≥40 kg/m2 after 18 years of age. There were 737 matched sets of cases and controls for the trajectory analysis. Weight and height data from birth through 5.5 years were abstracted from the medical records, and weight-for-age percentiles were obtained from the CDC growth charts. Results: A two-cluster weight-for-age trajectory solution was identified as optimal, with cluster 1 having higher weight-for-age before age 5.5 years. While there was no association between birth weight and severe adult obesity, the odds of being in cluster 1, which includes children with higher weight-for-age percentiles, was significantly increased for cases compared with controls [odds ratio (OR) 1.99, 95% confidence interval (CI) 1.60-2.47]. The association between cluster membership and case-control status persisted after adjusting for maternal age and education (adjusted OR 2.08, 95% CI 1.66-2.61). Conclusions: Our data suggest that early childhood weight-for-age trajectories are associated with severe obesity status in adult life. Our results add to growing evidence that it is critical to prevent excess early childhood weight gain.

Changes over time in latent patterns of childhood-to-adulthood BMI development in Great Britain: evidence from three cohorts born in 1946, 1958, and 1970

BACKGROUND

Most studies on secular trends in body mass index (BMI) are cross-sectional and the few longitudinal studies have typically only investigated changes over time in mean BMI trajectories. We aimed to describe how the evolution of the obesity epidemic in Great Britain reflects shifts in the proportion of the population demonstrating different latent patterns of childhood-to-adulthood BMI development.

METHODS

We used pooled serial BMI data from 25,655 participants in three British cohorts: the 1946 National Survey of Health and Development (NSHD), 1958 National Child Development Study (NCDS), and 1970 British Cohort Study (BCS). Sex-specific growth mixture models captured latent patterns of BMI development between 11 and 42 years. The classes were characterised in terms of their birth cohort composition.

RESULTS

The best models had four classes, broadly similar for both sexes. The 'lowest' class (57% of males; 47% of females) represents the normal weight sub-population, the 'middle' class (16%; 15%) represents the sub-population who likely develop overweight in early/mid-adulthood, and the 'highest' class (6%; 9%) represents those who likely develop obesity in early/mid-adulthood. The remaining class (21%; 29%) reflects a sub-population with rapidly 'increasing' BMI between 11 and 42 years. Both sexes in the 1958 NCDS had greater odds of being in the 'highest' class compared to their peers in the 1946 NSHD but did not have greater odds of being in the 'increasing' class. Conversely, males and females in the 1970 BCS had 2.78 (2.15, 3.60) and 1.87 (1.53, 2.28), respectively, times higher odds of being in the 'increasing' class.

CONCLUSIONS

Our results suggest that the obesity epidemic in Great Britain reflects not only an upward shift in BMI trajectories but also a more recent increase in the number of individuals demonstrating more rapid weight gain, from normal weight to overweight, across the second, third, and fourth decades of life.

Looking backwards and forwards: tracking and persistence of weight status between early childhood and adolescence

BACKGROUND/OBJECTIVE

Many studies have shown that child BMI or weight status tracks over time, but the demographic predictors of high tracking have not been investigated. Our objective was to identify demographic predictors of persistence (duration) of healthy weight and overweight/obesity throughout childhood, and to examine whether tracking was age dependent.

METHODS

We conducted secondary data analysis of 4606 children from the Birth cohort and 4983 children from the Kindergarten cohort of the Longitudinal Study of Australian Children with follow-up to age 12/13 and 16/17 years, respectively. Retrospective and prospective tracking were examined descriptively. Time-to-event analysis determined demographic predictors of persistence of healthy weight and overweight/obesity beyond age 4-5 years, after controlling for child BMI z-score. Weight status was determined using WHO methods.

RESULTS

Tracking of healthy weight was consistently higher than that of overweight/obesity, and incident overweight was equally likely throughout childhood and adolescence. Tracking of overweight was lower for children under 7 years than in middle childhood and adolescence (2-year probability 65%, compared with 80%; 2-year resolution of overweight 35 and 20%). Children of lower socioeconomic position, those from culturally and linguistically diverse backgrounds, and girls were more likely to move into overweight (hazard ratios [95%CI] for incident overweight: 1.39 [1.26-1.52], 1.16 [1.02-1.31] and 1.12 [1.02-1.23], respectively) and less likely to resolve their overweight (hazard ratios for resolution of overweight/obesity: 0.77 [0.69-0.85], 0.8 [0.69-0.92] and 0.79 [0.71-0.81], respectively) during childhood. However, persistence of weight status was not significantly affected by rurality or Indigenous status (P > 0.05).

CONCLUSIONS

Lowest tracking and highest natural resolution of overweight in children under 7 years suggests this may be an opportune time for interventions to reduce overweight. Primary and secondary prevention programmes during the school years should be designed with special consideration for lower socioeconomic communities, for culturally and linguistically diverse populations and for girls.

Community context, birth cohorts and childhood body mass index trajectories: Evidence from the China nutrition and health survey 1991-2011

Childhood overweight and obesity have shown an increase in recent birth cohorts. China has undergone rapid socioeconomic transitions accompanied by lifestyle changes that have profoundly affected the physical growth of children. Less empirical research has considered the role of community context on the cohort effects of children's body mass index (BMI) z-score trajectories. We used the mixed effect models for repeated measurements with restricted cubic spline to predict the BMI z-score trajectories in children aged 1-17 years, influenced by different birth cohorts and community context using data from the China Health and Nutrition Survey from 1991 to 2011, and stratified by sex. Results indicated that the mean of BMI z-scores of children aged 1-17 years have increased in the 2000s cohort. Community context contributed to significant differences in BMI z-score increase with age from middle childhood, and this trend of community inequalities divergences in middle childhood in recent birth cohorts. Therefore, to promote equitable growth for all children in China, policy interventions focusing on the community context may have far-reaching effects on the health of children and adolescents.

Trajectories of early to mid-life adulthood BMI and incident diabetes: the China Health and Nutrition Survey

INTRODUCTION

This longitudinal study aims to characterize distinct body mass index (BMI) trajectories during early to mid-life adulthood and to explore the association between BMI change from young adulthood to midlife and incident diabetes.

RESEARCH DESIGN AND METHODS

This study included 7289 adults who had repeatedly measured BMI 3-9 times during 1989-2011 and information on incident diabetes. Latent class growth mixed model (LCGMM) was used to identify different BMI trajectories. Cox proportional hazard models were used to investigate the association between the trajectory group membership and incident hyperglycemia, adjusting for covariates. The hyperglycemia group included individuals with prediabetes or diabetes. The model-estimated BMI levels and slopes were calculated at each age point in 1-year intervals according to the model parameters and their first derivatives, respectively. Logistic regression analyses were used to examine the association of model-estimated levels and slopes of BMI at each age point with incident hyperglycemia. The area under the curve (AUC) was computed from longitudinal growth curve models during the follow-up for each individual. Prior to the logistic regression analyses, quartiles of total, baseline, and incremental AUC values were calculated.

RESULTS

Three distinct trajectories were characterized by LCGMM, comprising of low-increasing group (n=5136), medium-increasing group (n=1914), and high-increasing group (n=239). Compared with the low-increasing group, adjusted HRs and 95% CIs were 1.21 (0.99 to 1.48) and 1.56 (1.06 to 2.30) for the medium-increasing and the high-increasing group, respectively. The adjusted standardized ORs of model-estimated BMI levels increased among 20-50 years, ranging from 0.98 (0.87 to 1.10) to 1.19 (1.08 to 1.32). The standardized ORs of level-adjusted linear slopes increased gradually from 1.30 (1.16 to 1.45) to 1.42 (1.21 to 1.67) during 20-29 years, then decreased from 1.41 (1.20 to 1.66) to 1.20 (1.08 to 1.33) during 30-43 years, and finally increased to 1.20 (1.04 to 1.38) until 50 years. The fourth quartile of incremental AUC (OR=1.31, 95% CI 1.03 to 1.66) was significant compared with the first quartile, after adjustment for covariates.

CONCLUSIONS

These findings indicate that the BMI trajectories during early adulthood were significantly associated with later-life diabetes. Young adulthood is a crucial period for the development of diabetes, which has implications for early prevention.

Turning the tables on obesity: young people, IT and social movements

Despite the rising incidence of childhood obesity, international data from Eurostat show that the prevalence of obesity among those aged 15-19 years remains under 5%, which offers an important opportunity for preventing subsequent adult obesity. Young people engage poorly, even obstructively, with conventional health initiatives and are often considered 'hard to reach'. However, when approached in the language of youth, via IT, they express great concern, and unwanted weight gain in young people can be prevented by age-appropriate, independent, online guidance. Additionally, when shown online how 'added value' by industry can generate consumer harms as free market 'externalities', and how obesogenic 'Big Food' production and distribution incur environmental and ethical costs, young people make lasting behavioural changes that attenuate weight gain. This evidence offers a novel approach to obesity prevention, handing the initiative to young people themselves and supporting them with evidence-based methods to develop, propagate and 'own' social movements that can simultaneously address the geopolitical concerns of youth and obesity prevention.

Changes and correlations in height from 7 to 69 years of age across the birth years of 1930 to 1989

OBJECTIVES

The aims of this study were to describe changes in height during childhood and to investigate potential changes in the proportion of children attaining final height in childhood and in correlations between child and adult height across birth cohorts.

METHODS

We included 363 059 children (179 906 girls) from the Copenhagen School Health Records Register, who were born between 1930 and 1989, with height measurements at ages 7, 10, or 13 years. Linkages to data resources containing adult height values between ages 18 and 69 years were possible for a subpopulation of 96 133 individuals (23 051 women). Birth years were categorized as 1930 to 1939, 1940 to 1949, and 1950 to 1989. Descriptive height statistics were estimated by birth years and birth cohorts. Height correlations were examined using sex- and age-specific partial Pearson correlation analyses and meta-regression techniques.

RESULTS

Across 60 birth years, mean child heights at age 7 increased by 2.9 cm in girls and 3.0 cm in boys, and adult heights increased as well. The proportions of children attaining final height by age 13 remained low across the birth cohorts; nonetheless, there was a significant increase from 0.7% to 1.5% in girls only (P < .0001). Both child-child and child-adult height correlations were strong and remained relatively stable across birth cohorts.

CONCLUSIONS

Mean child and adult height increased during the study period, but the proportion of children attaining final height at age 13 remained low. Child-child and child-adult height correlations were largely unchanged across birth cohorts.

Change in health and social factors in mid-adulthood and corresponding changes in leisure-time physical inactivity in a prospective cohort

Background

To identify whether changes in adult health and social factors are associated with simultaneous changes in inactivity.

Methods

Health, social factors and leisure-time inactivity (activity frequency < 1/week) were self-reported at 33y and 50y in the 1958 British birth cohort (N = 12,271). Baseline (33y) health and social factors and also patterns of change in factors 33y-to-50y were related to inactivity 33y-to-50y (never inactive, persistently inactive, deteriorating to inactivity, or improving from inactivity) using multinomial logistic regression.

Results

Approximately 31% were inactive at 33y and 50y; 35% changed status 33y-to-50y (17% deteriorating to inactivity, 18% improving from inactivity). Baseline poor health and obesity were associated with subsequent (33y-to-50y) inactivity; e.g. for poor health, relative risk ratios (RRRs) for deteriorating to inactivity (vs never inactive) and improving from inactivity (vs persistently inactive) were 1.38(1.16,1.64) and 0.77(0.63,0.94) respectively. Adverse changes in health and weight were associated with simultaneous adverse changes in inactivity; e.g. worsening health (vs always good/excellent health) was associated with higher risk of deteriorating to inactivity (RRR:2.20(1.85,2.62)) and lower risk of improving from inactivity (RRR:0.61(0.49,0.77)). However, improving health and weight loss were not associated with improving from inactivity. Worsening self-efficacy 33y-to-50y was associated with lower risk of improving from inactivity; there was no association between improving self-efficacy and inactivity change. Downward social mobility was not associated with deteriorating to or improving from inactivity. Changes in depression symptom level, marriage/co-habitation or parenthood 33y-to-50y were not associated with inactivity changes. No associations were observed for employment.

Conclusions

Associated changes in mid-life health factors with deleterious inactivity changes, highlight the importance of maintaining health, weight and self-efficacy across adulthood to deter inactivity.

Electronic supplementary material

The online version of this article (10.1186/s12966-018-0723-z) contains supplementary material, which is available to authorized users.

BMI Trajectories Associated With Resolution of Elevated Youth BMI and Incident Adult Obesity

BACKGROUND AND OBJECTIVES

Youth with high BMI who become nonobese adults have the same cardiovascular risk factor burden as those who were never obese. However, the early-life BMI trajectories for overweight or obese youth who avoid becoming obese adults have not been described. We aimed to determine and compare the young-childhood BMI trajectories of participants according to their BMI status in youth and adulthood.

METHODS

Bayesian hierarchical piecewise regression modeling was used to analyze the BMI trajectories of 2717 young adults who had up to 8 measures of BMI from childhood (ages 3-18 years) to adulthood (ages 34-49 years).

RESULTS

Compared with those with persistently high BMI, those who resolved their high youth BMI by adulthood had lower average BMI at age 6 years and slower rates of BMI change from young childhood. In addition, their BMI levels started to plateau at 16 years old for females and 21 years old for males, whereas the BMI of those whose high BMI persisted did not stabilize until 25 years old for male subjects and 27 years for female subjects. Compared with those youth who were not overweight or obese and who remained nonobese in adulthood, those who developed obesity had a higher BMI rate of change from 6 years old, and their BMI continued to increase linearly until age 30 years.

CONCLUSIONS

Efforts to alter BMI trajectories for adult obesity should ideally commence before age 6 years. The natural resolution of high BMI starts in adolescence for males and early adulthood for females, suggesting a critical window for secondary prevention.

Head circumference, leg length and its association with dementia among older adult population in Singapore

BACKGROUND

Head circumference and leg length serve as reliable proxy indicators of early-life environment. Research studies have shown that these anthropometric measurements are associated with cognitive impairment and dementia among older adults. The aim of the present study was to assess the associations between dementia with head circumference and leg length among the older adult population in Singapore. This study also aimed to examine the sociodemographic correlates of these anthropometric measurements.

METHODS

Data were collected from 2565 older adults aged 60 years and above, in a population study on the Well-being of the Singapore Elderly. Head circumference and leg length measurements were obtained, and sociodemographic information was recorded. Dementia diagnosis was made using the 10/66 dementia algorithm. Anthropometric measurements were first stratified into quarters, and then logistic regression analysis was used to examine factors associated with head circumference and leg length, as well as to examine the association between dementia with these measurements.

RESULTS

Sociodemographic correlates of head circumference and leg length include age, gender, ethnicity and education level. Smaller head circumference was independently associated with higher odds of 10/66 dementia (OR = 2.173-2.709). When the regression analysis was stratified by gender, the association was found only in the male sample. Leg length was not significantly associated with dementia after controlling for sociodemographic variables.

CONCLUSION

Smaller head circumference is independently associated with dementia among older adults in Singapore. Findings from this study suggest that risk factors for dementia begin their influence in early life. Copyright © 2017 John Wiley & Sons, Ltd.

Simulation of Growth Trajectories of Childhood Obesity into Adulthood

BACKGROUND

Although the current obesity epidemic has been well documented in children and adults, less is known about long-term risks of adult obesity for a given child at his or her present age and weight. We developed a simulation model to estimate the risk of adult obesity at the age of 35 years for the current population of children in the United States.

METHODS

We pooled height and weight data from five nationally representative longitudinal studies totaling 176,720 observations from 41,567 children and adults. We simulated growth trajectories across the life course and adjusted for secular trends. We created 1000 virtual populations of 1 million children through the age of 19 years that were representative of the 2016 population of the United States and projected their trajectories in height and weight up to the age of 35 years. Severe obesity was defined as a body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) of 35 or higher in adults and 120% or more of the 95th percentile in children.

RESULTS

Given the current level of childhood obesity, the models predicted that a majority of today's children (57.3%; 95% uncertainly interval [UI], 55.2 to 60.0) will be obese at the age of 35 years, and roughly half of the projected prevalence will occur during childhood. Our simulations indicated that the relative risk of adult obesity increased with age and BMI, from 1.17 (95% UI, 1.09 to 1.29) for overweight 2-year-olds to 3.10 (95% UI, 2.43 to 3.65) for 19-year-olds with severe obesity. For children with severe obesity, the chance they will no longer be obese at the age of 35 years fell from 21.0% (95% UI, 7.3 to 47.3) at the age of 2 years to 6.1% (95% UI, 2.1 to 9.9) at the age of 19 years.

CONCLUSIONS

On the basis of our simulation models, childhood obesity and overweight will continue to be a major health problem in the United States. Early development of obesity predicted obesity in adulthood, especially for children who were severely obese. (Funded by the JPB Foundation and others.).

Leisure-time physical activity across adulthood and biomarkers of cardiovascular disease at age 60-64: A prospective cohort study

Background and aims

This study examined associations between leisure-time physical activity (LTPA) across adulthood (from age 36) and cardiovascular disease (CVD) biomarkers at age 60–64.

Methods

LTPA was reported by study participants from the MRC National Survey of Health and Development at ages 36, 43, 53 and 60–64 (n = 1754) and categorised as inactive, moderately active (1–4/month) or most active (5+/month) at each age. Linear regression was used to examine associations between a cumulative adulthood LTPA score (range = 0–8), and change in LTPA between ages 36 and 60–64 (i.e. always inactive, became inactive, became active, always active) and inflammatory [C-reactive protein (CRP), interleukin-6 (IL-6)], endothelial [tissue-Plasminogen Activator (t-PA), E-selectin] and adipokine [leptin, adiponectin] measures extracted from overnight fasting blood samples at age 60–64.

Results

The more active a participant was over adulthood, the better their biomarker profile, e.g. fully-adjusted difference in t-PA (both sexes) and adiponectin (women) per unit increase in the LTPA score (95% confidence interval) = −2.2% (−3.6; −0.8) and 2.0% (0.2; 3.8). Those that became active at age 60–64 showed slightly healthier biomarker profiles than those that became inactive [e.g. fully-adjusted difference in IL-6 = −9.9% (−23.9; 4.1) vs. −3.8% (−12.4; 4.8)], although the best profiles were seen for those always active [IL-6: −15.0% (−24.2; −5.7)], when compared with the always inactive group.

Conclusions

Greater accumulation of LTPA across adulthood was associated with a more favourable CVD biomarker profile in early old age. Earlier uptake and long-term maintenance of LTPA may provide the greatest benefits for CVD prevention.

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Greater LTPA over 28 years related to healthier atherosclerotic biomarker profiles.

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Taking up LTPA related to better biomarker levels than staying inactive over life.

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Differences in biomarker levels by LTPA were only partly mediated by body size.

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Earlier uptake and long-term maintenance of LTPA may provide greatest benefits.

Bayesian hierarchical piecewise regression models: a tool to detect trajectory divergence between groups in long-term observational studies

Background

Bayesian hierarchical piecewise regression (BHPR) modeling has not been previously formulated to detect and characterise the mechanism of trajectory divergence between groups of participants that have longitudinal responses with distinct developmental phases. These models are useful when participants in a prospective cohort study are grouped according to a distal dichotomous health outcome. Indeed, a refined understanding of how deleterious risk factor profiles develop across the life-course may help inform early-life interventions. Previous techniques to determine between-group differences in risk factors at each age may result in biased estimate of the age at divergence.

Methods

We demonstrate the use of Bayesian hierarchical piecewise regression (BHPR) to generate a point estimate and credible interval for the age at which trajectories diverge between groups for continuous outcome measures that exhibit non-linear within-person response profiles over time. We illustrate our approach by modeling the divergence in childhood-to-adulthood body mass index (BMI) trajectories between two groups of adults with/without type 2 diabetes mellitus (T2DM) in the Cardiovascular Risk in Young Finns Study (YFS).

Results

Using the proposed BHPR approach, we estimated the BMI profiles of participants with T2DM diverged from healthy participants at age 16 years for males (95% credible interval (CI):13.5–18 years) and 21 years for females (95% CI: 19.5–23 years). These data suggest that a critical window for weight management intervention in preventing T2DM might exist before the age when BMI growth rate is naturally expected to decrease. Simulation showed that when using pairwise comparison of least-square means from categorical mixed models, smaller sample sizes tended to conclude a later age of divergence. In contrast, the point estimate of the divergence time is not biased by sample size when using the proposed BHPR method.

Conclusions

BHPR is a powerful analytic tool to model long-term non-linear longitudinal outcomes, enabling the identification of the age at which risk factor trajectories diverge between groups of participants. The method is suitable for the analysis of unbalanced longitudinal data, with only a limited number of repeated measures per participants and where the time-related outcome is typically marked by transitional changes or by distinct phases of change over time.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-017-0358-9) contains supplementary material, which is available to authorized users.

The use of measures of obesity in childhood for predicting obesity and the development of obesity-related diseases in adulthood: a systematic review and meta-analysis

BACKGROUND

It is uncertain which simple measures of childhood obesity are best for predicting future obesity-related health problems and the persistence of obesity into adolescence and adulthood.

OBJECTIVES

To investigate the ability of simple measures, such as body mass index (BMI), to predict the persistence of obesity from childhood into adulthood and to predict obesity-related adult morbidities. To investigate how accurately simple measures diagnose obesity in children, and how acceptable these measures are to children, carers and health professionals.

DATA SOURCES

Multiple sources including MEDLINE, EMBASE and The Cochrane Library were searched from 2008 to 2013.

METHODS

Systematic reviews and a meta-analysis were carried out of large cohort studies on the association between childhood obesity and adult obesity; the association between childhood obesity and obesity-related morbidities in adulthood; and the diagnostic accuracy of simple childhood obesity measures. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and a modified version of the Quality in Prognosis Studies (QUIPS) tool. A systematic review and an elicitation exercise were conducted on the acceptability of the simple measures.

RESULTS

Thirty-seven studies (22 cohorts) were included in the review of prediction of adult morbidities. Twenty-three studies (16 cohorts) were included in the tracking review. All studies included BMI. There were very few studies of other measures. There was a strong positive association between high childhood BMI and adult obesity [odds ratio 5.21, 95% confidence interval (CI) 4.50 to 6.02]. A positive association was found between high childhood BMI and adult coronary heart disease, diabetes and a range of cancers, but not stroke or breast cancer. The predictive accuracy of childhood BMI to predict any adult morbidity was very low, with most morbidities occurring in adults who were of healthy weight in childhood. Predictive accuracy of childhood obesity was moderate for predicting adult obesity, with a sensitivity of 30% and a specificity of 98%. Persistence of obesity from adolescence to adulthood was high. Thirty-four studies were included in the diagnostic accuracy review. Most of the studies used the least reliable reference standard (dual-energy X-ray absorptiometry); only 24% of studies were of high quality. The sensitivity of BMI for diagnosing obesity and overweight varied considerably; specificity was less variable. Pooled sensitivity of BMI was 74% (95% CI 64.2% to 81.8%) and pooled specificity was 95% (95% CI 92.2% to 96.4%). The acceptability to children and their carers of BMI or other common simple measures was generally good.

LIMITATIONS

Little evidence was available regarding childhood measures other than BMI. No individual-level analysis could be performed.

CONCLUSIONS

Childhood BMI is not a good predictor of adult obesity or adult disease; the majority of obese adults were not obese as children and most obesity-related adult morbidity occurs in adults who had a healthy childhood weight. However, obesity (as measured using BMI) was found to persist from childhood to adulthood, with most obese adolescents also being obese in adulthood. BMI was found to be reasonably good for diagnosing obesity during childhood. There is no convincing evidence suggesting that any simple measure is better than BMI for diagnosing obesity in childhood or predicting adult obesity and morbidity. Further research on obesity measures other than BMI is needed to determine which is the best tool for diagnosing childhood obesity, and new cohort studies are needed to investigate the impact of contemporary childhood obesity on adult obesity and obesity-related morbidities.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005711.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Population-level trends in the distribution of body mass index in England, 1992-2013

BACKGROUND

Changes over time of mean body weight or prevalence of overweight and obesity have been well documented. Less consideration has been given to describing the distribution to these changes particularly by socioeconomic status and sex.

METHODS

We use data from the Health Survey for England for the years 1992-2013 to calculate the median, 5th and 95th centiles, and SD of body mass index (BMI). We tested differences using analysis of variance and quantile regression. Analyses were stratified by sex and level of education.

RESULTS

There have been increases in the SD of BMI values over the period. While median BMI has increased, there has been a larger increase of the 95th centile. These trends were consistent by sex and level of education, although significant differences were observed in values.

CONCLUSIONS

Our results demonstrate that changes in median BMI over time do not reflect changes in the distribution of BMI. Failing to understand the distribution of body weight in the population will hamper our projections of future patterns, as well as our ability to design effective public health strategies.

Life-course body mass index trajectories and blood pressure in mid life in two British birth cohorts: stronger associations in the later-born generation

Background: Little is known about the impact of recent increases in obesity and more rapid gains in body mass index (BMI) on cardiovascular risk factors. We investigated life-course BMI trajectories associations with adult blood pressure (BP) across two generations.

Methods: We used the the 1946 and 1958 British birth cohorts. Joint multivariate response models were fitted to longitudinal BMI measures [7, 11, 16, 20, 26, 36, 43 and 50 y (years): 1946 cohort, n = 4787; 7, 11, 16, 23, 33 and 45 y: 1958 cohort, n = 16 820] and mid-adult BP. We adopted linear spline models with random coefficients to characterize childhood and adult BMI slopes.

Results: Mean systolic BP (SBP) decreased from the earlier- to later-born cohort by 2.8 mmHg in females, not males; mean diastolic BP (DBP) decreased by 3.2-3.3 mmHg (both sexes). Adult BMI was higher in the later- than the earlier-born cohort by 1.3-1.8 kg/m², slopes of BMI trajectory were steeper from early adulthood and associations with adult BP were stronger. Associations between adult BMI and SBP were stronger in the later-born cohort. For males, childhood BMI slope was associated with SBP only in the later-born cohort; the association for adult BMI slope was stronger in the later-born cohort: correlation coefficient r = 0.28 [95% confidence interval (CI): 0.25,0.33] versus 0.13 (0.06,0.20). For females, childhood slope was associated with SBP in both cohorts; adult slope was associated with SBP only in the 1958 cohort [r = 0.34 (0.31,0.37)]. Patterns of child-to-adult BMI associations were similar in relation to DBP.

Conclusions: BP did not increase between two generations born 12 y apart despite higher BMI levels. A stronger association between BMI trajectory and BP in the later-born cohort suggests that BMI-related effects may have been offset by improvements in other factors linked to BP, such as diet and smoking.

Socioeconomic inequalities in health trajectories in Switzerland: are trajectories diverging as people age?

Do socioeconomic differences in health status increase as people age, reflecting cumulative advantage or disadvantage in health trajectories? Life course research hypothesises that cumulative advantage/disadvantage (CAD) is an important underlying social process that shape inequalities as people age. The objective of this study is to examine whether health trajectories are diverging as people age across socioeconomic positions (education, employment status and income). In a random sample of 3,665 respondents living in Switzerland (Swiss Household Panel 2004-2011), trajectories of self-rated health, body mass index, depression and medicated functioning were examined with multilevel regression models. The results showed that employment status and income were associated with diverging health trajectories among men; however, only a few associations supported the CAD hypothesis. Education was rarely associated with diverging health trajectories. In conclusion, little evidence was found to support the CAD model.

How Has the Age-Related Process of Overweight or Obesity Development Changed over Time? Co-ordinated Analyses of Individual Participant Data from Five United Kingdom Birth Cohorts

BACKGROUND

There is a paucity of information on secular trends in the age-related process by which people develop overweight or obesity. Utilizing longitudinal data in the United Kingdom birth cohort studies, we investigated shifts over the past nearly 70 years in the distribution of body mass index (BMI) and development of overweight or obesity across childhood and adulthood.

METHODS AND FINDINGS

The sample comprised 56,632 participants with 273,843 BMI observations in the 1946 Medical Research Council National Survey of Health and Development (NSHD; ages 2-64 years), 1958 National Child Development Study (NCDS; 7-50), 1970 British Cohort Study (BCS; 10-42), 1991 Avon Longitudinal Study of Parents and Children (ALSPAC; 7-18), or 2001 Millennium Cohort Study (MCS; 3-11). Growth references showed a secular trend toward positive skewing of the BMI distribution at younger ages. During childhood, the 50th centiles for all studies lay in the middle of the International Obesity Task Force normal weight range, but during adulthood, the age when a 50th centile first entered the overweight range (i.e., 25-29.9 kg/m2) decreased across NSHD, NCDS, and BCS from 41 to 33 to 30 years in males and 48 to 44 to 41 years in females. Trajectories of overweight or obesity showed that more recently born cohorts developed greater probabilities of overweight or obesity at younger ages. Overweight or obesity became more probable in NCDS than NSHD in early adulthood, but more probable in BCS than NCDS and NSHD in adolescence, for example. By age 10 years, the estimated probabilities of overweight or obesity in cohorts born after the 1980s were 2-3 times greater than those born before the 1980s (e.g., 0.229 [95% CI 0.219-0.240] in MCS males; 0.071 [0.065-0.078] in NSHD males). It was not possible to (1) model separate trajectories for overweight and obesity, because there were few obesity cases at young ages in the earliest-born cohorts, or (2) consider ethnic minority groups. The end date for analyses was August 2014.

CONCLUSIONS

Our results demonstrate how younger generations are likely to accumulate greater exposure to overweight or obesity throughout their lives and, thus, increased risk for chronic health conditions such as coronary heart disease and type 2 diabetes mellitus. In the absence of effective intervention, overweight and obesity will have severe public health consequences in decades to come.

A life-course approach to healthy ageing: maintaining physical capability

Research on healthy ageing lacks an agreed conceptual framework and has not adequately taken into account the growing evidence that social and biological factors from early life onwards affect later health. We conceptualise healthy ageing within a life-course framework, separating healthy biological ageing (in terms of optimal physical and cognitive functioning, delaying the onset of chronic diseases, and extending length of life for as long as possible) from changes in psychological and social wellbeing. We summarise the findings of a review of healthy ageing indicators, focusing on objective measures of physical capability, such as tests of grip strength, walking speed, chair rises and standing balance, which aim to capture physical functioning at the individual level, assessing the capacity to undertake the physical tasks of daily living. There is robust evidence that higher scores on these measures are associated with lower rates of mortality, and more limited evidence of lower risk of morbidity, and of age-related patterns of change. Drawing on a research collaboration of UK cohort studies, we summarise what is known about the influences on physical capability in terms of lifetime socioeconomic position, body size and lifestyle, and underlying physiology and genetics; the evidence to date supports a broad set of factors already identified as risk factors for chronic diseases. We identify a need for larger longitudinal studies to investigate age-related change and ethnic diversity in these objective measures, the dynamic relationships between them, and how they relate to other component measures of healthy ageing. Robust evidence across cohort studies, using standardised measures within a clear conceptual framework, will benefit policy and practice to promote healthy ageing.

Socioeconomic position across life and body composition in early old age: findings from a British birth cohort study

BACKGROUND

Previous studies have reported associations between lower lifetime socioeconomic position (SEP) and higher body mass index in adulthood, but few have examined associations with direct measures of fat and lean mass which are likely to have independent roles in health and physical functioning.

METHODS

We examined associations of SEP across life with dual-energy X-ray absorptiometry measures of fat and lean mass at 60-64 years using data from a total of 1558 men and women participating in the Medical Research Council (MRC) National Survey of Health and Development. We also examined whether associations of childhood SEP with fat and lean mass were explained by preadulthood weight gain (birth weight, 0-7 and 7-20 years) and adult SEP.

RESULTS

Lower SEP across life was associated with higher fat mass and higher android to gynoid fat mass ratio. For example, the mean difference in fat mass index comparing the lowest with the highest paternal occupational class at 4 years (slope index of inequality) was 1.04 kg/m(1.2) in men (95% CI 0.09 to 1.99) and 2.61 in women (1.34 to 3.89), equivalent to a 8.6% and 16.1% difference, respectively. After adjustment for fat mass, lower SEP across life was associated with lower lean mass in women, while only contemporaneous household income was associated in men. Associations between childhood SEP and outcomes were partly explained by preadulthood weight gain and adult SEP.

CONCLUSIONS

This study identified lifetime socioeconomic patterning of fat and lean mass in early old age. This is likely to have important implications and may partly explain socioeconomic inequalities in health and physical functioning.

Differences in adiposity trajectories by birth cohort and childhood social class: evidence from cohorts born in the 1930s, 1950s and 1970s in the west of Scotland

Background

Since the 1930s, the environment has become increasingly obesogenic, leading to rising rates of adiposity and socioeconomic inequalities in adiposity. Building on studies comparing body mass index (BMI) for cohorts born over a period of 20 years, we examine the social patterning of BMI and central adiposity for three cohorts born over a 40-year period.

Methods

Using data from the West of Scotland Twenty-07 study (n=4510), we investigate 20-year trajectories of adiposity for three cohorts born in the 1930s, 1950s and 1970s, allowing us to study 60 years of the lifecourse. Stratified by gender, we employed multilevel models to generate trajectories for BMI and waist-to-height ratio (WHtR) and explored how these trajectories varied by childhood social class.

Results

Adiposity increased most quickly with age in the youngest cohort, and cohort differences were greater than socioeconomic differences. For example, the smallest cohort difference for BMI, a comparison of men in the 1930s and 1950s cohorts at age 55, was 2.66 (95% CI 2.11 to 3.20) kg/m², while the largest socioeconomic difference, a comparison of manual and non-manual women at age 64, was 1.18 (95% CI 0.37 to 1.98) kg/m². Socioeconomic inequalities in adiposity increased with age and were greater for women than for men. The results for WHtR differed in that increases in WHtR accelerated with age while increases in BMI slowed.

Conclusions

Socioeconomic differences in adiposity accumulate slowly across the lifecourse and are approximately only a third of the adiposity differences between cohorts.

Longitudinal follow-up of the relationship between dietary intake and growth and development in the Lifeways cross-generation cohort study 2001-2013

In this paper we will review evidence on the early life and familial influences on childhood growth and development, with particular reference to the Lifeways cross-generation cohort study in the Republic of Ireland. The Lifeways cross-generation cohort study was established in 2001-2013 through two maternity hospitals in the Republic of Ireland and was one of many new cohort studies established worldwide in the millennium period. Mothers were recruited at first booking visit, completing a self-administered questionnaire, which included a 147 item semi-quantitative FFQ. Longitudinal follow-up is ongoing in 2013, with linkage data to hospital and general practice records and examination of children when aged 5 and 9 years. The study is one of very few containing data on grandparents of both lineages with at least one grandparent recruited at baseline. There have been consistent associations between parental and grandparental health status characteristics and children's outcomes, including infant birth-weight, BMI when child was aged 5 years and childhood wheeze or asthma when child was aged 3 and aged 5 years. In conclusion, empirical evidence to date shows consistent familial and cross-generational patterns, particularly in the maternal line.

Childhood stunting and mortality between 36 and 64 years: the British 1946 Birth Cohort Study

BACKGROUND

Our aim was to examine the associations between childhood or adult height and adult mortality.

METHODS

In the prospective British 1946 Birth Cohort Study, childhood height was measured at 2, 4, 6, 7, 11, and 15 years, and adult height was measured at 36 years. Deaths were reported from the national health service register.

RESULTS

A total of 3877 study members (1963 male) contributed 106,333 person-years of follow-up; 391 deaths (228 male) were reported between the ages of 36 and 64 years. The strongest sex-adjusted association between height and mortality between ages 36 and 64 years was seen for height at age 6 years. The association was nonlinear; only study members in the shortest quintile at 6 years had a higher relative risk of adult mortality compared with those in the tallest quintile. By contemporary growth standards, 5.7% (n = 188) had heights at 6 years less than the second percentile, and a further 15.0% (n = 490) had heights between the second to ninth percentiles; these groups had higher adult mortality than all other study members (hazard ratio, 2.18; 95% confidence interval, 1.52-3.13; P < .001; and hazard ratio, 1.42; 95% confidence interval, 1.08-1.88; P = .01, respectively). Several determinants of childhood stunting (height at 6 years less than the second percentile) were directly associated with adult mortality; these included shorter parental heights and adverse early life nutrition and housing.

CONCLUSIONS

British men and women born in 1946 were relatively stunted as children by contemporary standards. Those who were short at age 6 years had substantially higher mortality 30 to 60 years later. Furthermore, they accounted for the well-recognized inverse association between adult height and mortality.

Body mass index, muscle strength and physical performance in older adults from eight cohort studies: the HALCyon programme

Objective

To investigate the associations of body mass index (BMI) and grip strength with objective measures of physical performance (chair rise time, walking speed and balance) including an assessment of sex differences and non-linearity.

Methods

Cross-sectional data from eight UK cohort studies (total N = 16 444) participating in the Healthy Ageing across the Life Course (HALCyon) research programme, ranging in age from 50 to 90+ years at the time of physical capability assessment, were used. Regression models were fitted within each study and meta-analysis methods used to pool regression coefficients across studies and to assess the extent of heterogeneity between studies.

Results

Higher BMI was associated with poorer performance on chair rise (N = 10 773), walking speed (N = 9 761) and standing balance (N = 13 921) tests. Higher BMI was associated with stronger grip strength in men only. Stronger grip strength was associated with better performance on all tests with a tendency for the associations to be stronger in women than men; for example, walking speed was higher by 0.43 cm/s (0.14, 0.71) more per kg in women than men. Both BMI and grip strength remained independently related with performance after mutual adjustment, but there was no evidence of effect modification. Both BMI and grip strength exhibited non-linear relations with performance; those in the lowest fifth of grip strength and highest fifth of BMI having particularly poor performance. Findings were similar when waist circumference was examined in place of BMI.

Conclusion

Older men and women with weak muscle strength and high BMI have considerably poorer performance than others and associations were observed even in the youngest cohort (age 53). Although causality cannot be inferred from observational cross-sectional studies, our findings suggest the likely benefit of early assessment and interventions to reduce fat mass and improve muscle strength in the prevention of future functional limitations.

Life course body mass index, birthweight and lipid levels in mid-adulthood: a nationwide birth cohort study

AIMS

Improvement in lipid profiles is an important public health and clinical goal for which a better understanding is needed of biological pathways and influences. Evidence is scant on the role of growth, including trajectories of body mass index (BMI), so we aimed to determine whether particular life stages from birth to adulthood are important for lipid levels in mid-adulthood (45 years).

METHODS AND RESULTS

In the 1958 British birth cohort (n = 3927 men; 3897 women), weight and height were recorded at: birth (weight only), 7, 11, 16, 23, 33, and 45 years. Birthweight was inversely associated with triglycerides and in women with total- and non-high-density lipoprotein cholesterol; associations were little affected by adjustment for 7-year BMI. Associations between lipids and BMI strengthened with age, e.g. in women, adult (45-year) triglycerides were elevated by 1.54% (95% confidence interval: 0.87-2.21%) and 3.57% (3.29-3.86%), respectively, per kg/m² higher BMI at 11 and 45 years. Body mass index gain was related to lipids, with strongest associations for the interval between 33 and 45 years, where a kg/m² gain in BMI was associated with ~0.6% higher total cholesterol and ~5.3% higher triglycerides. Associations between 45-year BMI and lipids were stronger for those with lowest than highest BMI at younger ages (P for interaction ≤0.05). A long duration of obesity and obesity in childhood but not thereafter were unrelated to adult lipid levels.

CONCLUSIONS

Our findings from a large population-based cohort highlight detrimental consequences of high adult BMI for lipids as most pronounced for those with a lower BMI at earlier life stages.

Timing of voice breaking in males associated with growth and weight gain across the life course

BACKGROUND

In contrast to the many studies in females, there are few data in males on the relationships between childhood growth and weight gain and the timing of pubertal maturation and its relevance to adult body mass index (BMI) and body composition.

METHODS

A total of 2008 males in the 1946 British Birth Cohort Study had assessment of pubertal status including voice-breaking status (no change, starting, or complete) at age 14 yr. These responses were related to growth measurements at birth (weight only) and at 2, 4, 6, 7, 11, 14, 20, 26, 36, 43, 53, and 60-64 yr. Body composition was assessed by dual-energy x-ray absorptiometry at 60-64 yr.

RESULTS

Males with more advanced voice-breaking status at age 14 yr had similar birth weights compared with other males; they showed faster weight gain from 0-2 yr and had higher mean weight and BMI at age 2 yr. Subsequently, they continued to accelerate in weight and BMI, and also in height, and maximum differences in body size were seen at age 14 yr. Adult height did not differ between groups, but males with advanced voice breaking had higher adult BMI and greater whole-body lean mass and greater android fat mass at 60-64 yr.

CONCLUSION

Similar to females with earlier menarche, the trajectory to earlier sexual maturation in males is manifested by faster early postnatal growth and weight gain and leads to higher adult BMI. Timing of pubertal maturation has potential relevance to adult disease risks in males. We also describe conditional height difference in sd score as a proxy marker of pubertal timing in males.

Adult obesity susceptibility variants are associated with greater childhood weight gain and a faster tempo of growth: the 1946 British Birth Cohort Study

BACKGROUND

Longitudinal growth associations with genetic variants identified for adult BMI may provide insights into the timing of obesity susceptibility.

OBJECTIVE

The objective was to explore associations of known BMI loci with measures of body size from birth to adulthood.

DESIGN

A total of 2537 individuals from a longitudinal British birth cohort were genotyped for 11 genetic variants robustly associated with adult BMI (in/near FTO, MC4R, TMEM18, GNPDA2, KCTD15, NEGR1, BDNF, ETV5, SEC16B, SH2B1, and MTCH2). We derived an obesity-risk-allele score, comprising the sum of BMI-increasing alleles in each individual, and examined this for an association with birth weight and repeated measures of weight, height, and BMI SD scores (SDS) at 11 time points between ages 2 and 53 y.

RESULTS

The obesity-risk-allele score showed borderline significant association with birth weight (0.019 SDS/allele; P = 0.05) and was more clearly associated with higher weight and BMI at all time points between ages 2 and 53 y; the strongest associations with weight occurred at ages 11 and 20 y (both 0.056 SDS/allele). In longitudinal analyses, the score was positively associated with weight gain only between birth and 11 y (0.003 SDS/allele per year; 95% CI: 0.001, 0.004; P = 0.001). The risk-allele score was associated with taller height at 7 y (0.031 SDS/allele; P = 0.002) and greater height gains between 2 and 7 y (0.007 SDS/allele per year; P < 0.001), but not with adult height (P = 0.5).

CONCLUSIONS

The combined effect of adult obesity susceptibility variants on weight gain was confined to childhood. These variants conferred a faster tempo of height growth that was evident before the pubertal years.

Life course models of socioeconomic position and cardiovascular risk factors: 1946 birth cohort

PURPOSE

To identify the life course model that best describes the association between life course socioeconomic position (SEP) and cardiovascular (CVD) risk factors (ie, body mass index [BMI], systolic and diastolic blood pressure, total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides, and glycated hemoglobin) and explore BMI across the life course as mediators of the relationship.

METHODS

The Medical Research Council National Survey of Health and Development was used to compare partial F-tests of simpler nested life course SEP models corresponding to critical period, accumulation, and social mobility models with a saturated model. Then, the chosen life course model for each CVD risk factor was adjusted for BMI at age 53 and lifetime BMI (ages 4, 26, 43, and 53 years).

RESULTS

Among women, SEP was generally associated with CVD risk factors in a cumulative manner, whereas childhood critical period was the prominent model for men. When the best-fitting SEP models were used, we found that adjustment for BMI at age 53 reduced associations for all outcomes in both genders. Further adjustment for lifetime BMI (4, 26, 43, and 53 years) did not substantially alter most associations (except for triglycerides).

CONCLUSIONS

SEP at different points across life influences CVD risk factors differently in men and women.

Predicting cardiovascular disease risk factors in midadulthood from childhood body mass index: utility of different cutoffs for childhood body mass index

BACKGROUND

Identifying adults at increased risk of cardiovascular disease (CVD) on the basis of childhood body mass index (BMI) could be informative for disease prevention but depends on the utility of childhood BMI cutoffs.

OBJECTIVE

We aimed to establish how well the International Obesity Task Force (IOTF) and population-specific cutoffs for childhood BMI predict CVD risk factors in midadulthood.

DESIGN

We used the 1958 British birth cohort, whose BMI measures were collected at 7, 11, and 16 y and whose CVD risk factors (obesity, hypertension, adverse lipid concentrations, and type 2 diabetes risk) were collected at 45 y. The sensitivity and specificity of IOTF and population-specific cutoffs for childhood BMI were calculated for each CVD risk factor.

RESULTS

The prevalence of overweight or obesity was low in childhood (<11%, IOTF cutoffs) compared with that in adulthood (75% men, 56% women). The IOTF cutoffs had high specificities (91.6-97.9%) but low sensitivities (7.1-31.5%) for predicting adult outcomes. In comparison, population-specific cutoffs identified large groups of children (eg, >38% for predicting adult obesity) who had improved sensitivities (17.3-67.3%) but lower specificities (52.9-84.6%) compared with IOTF cutoffs. Accelerated BMI gains in childhood predicted adult obesity and type 2 diabetes risk, but prediction was no greater than that for childhood BMI at one age (area under the curve: 0.55-0.65 compared with 0.59-0.75). Childhood BMI and BMI gain were weak predictors of adult hypertension and adverse lipid concentrations.

CONCLUSION

Neither the IOTF cutoffs nor our population-specific cutoffs for childhood BMI are adequate diagnostic tools for adult CVD risk factors in a population experiencing rapid changes in obesity prevalence over their lifetime.

Lifecourse childhood adiposity trajectories associated with adolescent insulin resistance

OBJECTIVE

In light of the obesity epidemic, we aimed to characterize novel childhood adiposity trajectories from birth to age 14 years and to determine their relation to adolescent insulin resistance.

RESEARCH DESIGN AND METHODS

A total of 1,197 Australian children with cardiovascular/metabolic profiling at age 14 years were studied serially from birth to age 14 years. Semiparametric mixture modeling was applied to anthropometric data over eight time points to generate adiposity trajectories of z scores (weight-for-height and BMI). Fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were compared at age 14 years between adiposity trajectories.

RESULTS

Seven adiposity trajectories were identified. Three (two rising and one chronic high adiposity) trajectories comprised 32% of the population and were associated with significantly higher fasting insulin and HOMA-IR compared with a reference trajectory group (with longitudinal adiposity z scores of approximately zero). There was a significant sex by trajectory group interaction (P < 0.001). Girls within a rising trajectory from low to moderate adiposity did not show increased insulin resistance. Maternal obesity, excessive weight gain during pregnancy, and gestational diabetes were more prevalent in the chronic high adiposity trajectory.

CONCLUSIONS

A range of childhood adiposity trajectories exist. The greatest insulin resistance at age 14 years is seen in those with increasing trajectories regardless of birth weight and in high birth weight infants whose adiposity remains high. Public health professionals should urgently target both excessive weight gain in early childhood across all birth weights and maternal obesity and excessive weight gain during pregnancy.

Expression of CYP19 and CYP17 is associated with leg length, weight, and BMI

This study investigates associations between gene expressions of aromatase (CYP19), 17α hydroxylase (CYP17), and estrogen receptors α and β and anthropometric measurements in offspring of the Michigan fish eater cohort. Leg and trunk length, height, weight, and BMI and gene expression in peripheral blood cells were measured in offspring of the Michigan fish eater cohort. The parental generation was followed between 1973 and 1991, and maternal age, height, and weight data were collected. Female offspring were contacted in 2001/2002 and followed up in 2006/2007; offspring information included age, education, reproductive history, smoking, and exercise. Gene expression was standardized against 18S ribosomal ribonucleic acid (18SrRNA) and RNA polymerase II (RNA PolII) expressions. Mixed models assessed the statistical effect of gene expression on anthropometric outcomes, accounting for multiple offspring from one mother. Anthropometric measurements and gene expression were measured in 139 female offspring. The two length and the height measurements were correlated, as were BMI and weight. CYP19 expression was correlated with the other gene expressions and both estrogen receptor expressions were associated. For every 1 unit of ΔC(t) (18SrRNA - CYP19) or ΔC(t) (RNA PolII - CYP19), BMI was increased by 0.9 (P = 0.03) and 0.87 kg/m(2) (P = 0.04), respectively, and weight by 2.35 kg (P = 0.03) and 2.1 kg (P = 0.03), respectively. For every 1 unit of ΔC(t) (18SrRNA - CYP17), leg length was increased by 0.84 cm (P = 0.04). The results suggest that CYP17 gene expression may influence growth during childhood and adolescence while CYP19 may be associated with the concurrent measures of weight and BMI.

Childhood, adolescent and early adult body mass index in relation to adult mortality: results from the British 1946 birth cohort

BACKGROUND

Adult body mass index (BMI) has been consistently related to mortality, but little is known about the impact of earlier life BMI on adult mortality. The aim is to investigate the impact of childhood, adolescent and early adult BMI on premature adult all-cause mortality.

METHODS

The British 1946 cohort study was used to assess the association of BMI in childhood, adolescence and adulthood with mortality 26-60 years (332 deaths). 4462 (83%) respondents were available for analysis at age 26 years. Splines were used in Cox regression to model the associations between BMI and mortality.

RESULTS

In both genders, adult BMI from 20 years onwards showed a consistent U-shaped relationship with adult mortality (overall p value <0.05 for BMI at ages 20, 26 and 36 years). In women, a similar relationship was observed for adolescent BMI at 15 years (p=0.02); the HR comparing women with low BMI (2 SDs below mean) versus mean BMI was 2.96 (95% CI 1.26 to 6.97). The corresponding HR for women with BMI 2 SDs above the mean was 1.97 (0.95 to 4.10). BMI in childhood was generally not associated with adult mortality except female BMI at 4 years where a U-shaped relationship was observed (p=0.02); HR for BMI 2 SDs below mean versus mean was 2.13 (0.97 to 4.70) and the corresponding HR for 2 SDs above the mean was 1.67 (0.85 to 3.28). This association was not attenuated by subsequent BMI change or mediators.

CONCLUSIONS

High and low BMI from early adulthood were related to adult premature mortality suggesting that promoting a normal weight in early adulthood could prevent premature mortality.

Body mass trajectories through adulthood: results from the National Longitudinal Survey of Youth 1979 Cohort (1981-2006)

BACKGROUND

Most studies describing change in body mass through adulthood model an 'average' trajectory bearing the same functional form in the underlying population. Latent-class growth modelling has revealed the presence of several underlying body mass/obesity trajectory groups among children and adolescents, but has not been applied to capture adult body mass trajectories. We apply the technique to identify adult body mass trajectory groups, risk factors for group membership and (time-varying) modifiers of trajectory level within each group, and assess association between group membership and important health outcomes in midlife.

METHODS

Body mass trajectory groups, from age 18 to 49 years, were identified using latent-class growth modelling based on the National Longitudinal Survey of Youth 1979 (n = 9681). Role of gender, race/ethnicity and age cohort as risk factors for group membership, and of highest grade of education completed, years of urban living, years in employment, years in poverty and years married as modifiers of trajectory level was evaluated.

RESULTS

Four trajectory groups, 'normal weight', 'overweight', 'late adulthood obesity' and 'early adulthood obesity' were identified. Males, Blacks and those born later had higher odds of being in the three latter groups. More education and years married lowered the trajectory within each group. The prevalence of most health outcomes was lowest in the 'normal weight' group, somewhat greater in the 'overweight' group, greater again in the 'late adult obesity group' and highest in the 'early adulthood obesity' group.

CONCLUSION

Regular body mass index screening and monitoring in early adult life may identify a person as belonging to one of these four groups early, and allow the individual and health-care providers opportunities to initiate behavioural or other interventions better tailored to the specific group.

Development of new demi-span equations from a nationally representative sample of adults to estimate maximal adult height

Various measures have been used to estimate height when assessing nutritional status. Current equations to obtain demi-span equivalent height (DEH(Bassey)) are based on a small sample from a single study. The objectives of this study were to develop more robust DEH equations from a large number of men (n = 591) and women (n = 830) aged 25-45 y from a nationally representative cross-sectional sample (Health Survey for England 2007). Sex-specific regression equations were produced from young adults' (aged 25-45 y) measured height and demi-span to estimate new DEH equations (DEH(new)). DEH in people aged >or= 65 y was calculated using DEH(new). DEH(new) estimated current height in people aged 25-45 y with a mean difference of 0.04 in men (P = 0.80) and -0.29 in women (P = 0.05). Height, demi-span, DEH(new), and DEH(Bassey) declined by age group in both sexes aged >or=65 y (P < 0.05); DEH were larger than the measured height for all age groups (mean difference between DEH(new) and current height was -2.64 in men and -3.16 in women; both P < 0.001). Comparisons of DEH estimates showed good agreement, but DEH(new) was significantly higher than DEH(Bassey) in each age and sex group in older people. The new equations that are based on a large, randomly selected, nationally representative sample of young adults are more robust for predicting current height in young adults when height measurements are unavailable and can be used in the future to predict maximal adult height more accurately in currently young adults as they age.

Trends in the prevalence of obesity and overweight in English adults by age and birth cohort, 1991-2006

OBJECTIVE

To describe trends in the prevalence of obesity and overweight in English adults.

DESIGN

Analysis of nationally representative cross-sectional population surveys. Sociodemographic information was gathered by an interviewer-administered questionnaire and measurements of height and weight were used to calculate the prevalence of obesity and overweight.

SUBJECTS

A total of 61 515 men and 69 733 women aged 16-65 years participating in the annual Health Survey for England between 1991 and 2006.

RESULTS

When the 4-year periods 1991/94 and 2003/06 were compared, male and female obesity had risen by 8.2 % and 6.0 %, and male and female overweight had risen by 8.8 % and 7.4 %. However, the rate of increase appears to be slowing down: the increases between 1995/98 and 1999/02 were greater than those between 1999/02 and 2003/06. There was relatively little variation across the age range in the average changes in obesity or overweight prevalence between time periods, except that the increase in male obesity between periods was significantly greater for older than younger males. When the subjects were divided into 10-year pseudo birth cohorts, it was seen that the prevalence of obesity and overweight was consistently higher at a given average age for pseudo cohorts born more recently. This agreed with data from two British cohort studies.

CONCLUSIONS

Obesity and overweight continued to rise over the study period, but there are signs that the rate of increase is slowing down, even though the prevalence is consistently higher for a given age in cohorts born more recently.

Life course variations in the associations between FTO and MC4R gene variants and body size

The timing of associations between common genetic variants for weight or body mass index (BMI) across the life course may provide insights into the aetiology of obesity. We genotyped variants in FTO (rs9939609) and near MC4R (rs17782313) in 1240 men and 1239 women born in 1946 and participating in the MRC National Survey of Health and Development. Birth weight was recorded and height and weight were measured or self-reported repeatedly at 11 time-points between ages 2 and 53 years. Hierarchical mixed models were used to test whether genetic associations with weight or BMI standard deviation scores (SDS) changed with age during childhood and adolescence (2–20 years) or adulthood (20–53 years). The association between FTO rs9939609 and BMI SDS strengthened during childhood and adolescence (rate of change: 0.007 SDS/A-allele/year; 95% CI: 0.003–0.010, P < 0.001), reached a peak strength at age 20 years (0.13 SDS/A-allele, 0.08–0.19), and then weakened during adulthood (−0.003 SDS/A-allele/year, −0.005 to −0.001, P = 0.001). MC4R rs17782313 showed stronger associations with weight than BMI; its association with weight strengthened during childhood and adolescence (0.005 SDS/C-allele/year; 0.001–0.008, P = 0.006), peaked at age 20 years (0.13 SDS/C-allele, 0.07–0.18), and weakened during adulthood (−0.002 SDS/C-allele/year, −0.004 to 0.000, P = 0.05). In conclusion, genetic variants in FTO and MC4R showed similar biphasic changes in their associations with BMI and weight, respectively, strengthening during childhood up to age 20 years and then weakening with increasing adult age. Studies of the aetiology of obesity spanning different age groups may identify age-specific determinants of weight gain.