An obesogenic postnatal environment is more important than the fetal environment for the development of adult adiposity: a study of female twins

Birthweight-for-gestational-age z-scores are associated with early childhood cardiometabolic health in the Peri/Postnatal Epigenetic Twin Study

Birthweight has been consistently related to risk of cardiometabolic disorders in later life. Twins are at higher risk of low birthweight than singletons, so understanding the links between birthweight and cardiometabolic health may be particularly important for twins. However, evidence for the association of birthweight with childhood markers of cardiometabolic health in twins is currently lacking. Previous studies have often failed to appropriately adjust for gestational age or fully implement twin regression models. Therefore, we aimed to evaluate the association of birthweight-for-gestational-age z-scores with childhood cardiometabolic health in twins, using within-between regression models. The Peri/Postnatal Epigenetic Twins Study is a Melbourne-based prospective cohort study of 250 twin pairs. Birthweight was recorded at delivery, and childhood anthropometric measures were taken at 18-month and 6-year follow-up visits. Associations of birthweight with markers of cardiometabolic health were assessed at the individual, between- and within-pair level using linear regression with generalised estimating equations. Birthweight-for-gestational-age z-scores were associated with height, weight and BMI at 18 months and 6 years, but not with blood pressure (twins-as-individual SBP: β = 0.15, 95% CI: -0.81, 1.11; twins-as-individual DBP: β = 0.22, 95% CI: -0.34, 0.77). We found little evidence to indicate that the within-between models improved on the twins-as-individuals models. Birthweight was associated with childhood anthropometric measures, but not blood pressure, after appropriately adjusting for gestational age. These associations were consistent across the within-between and twins-as-individuals models. After adjusting for gestational age, results from the twins-as-individuals models are consistent with singleton studies, so these results can be applied to the general population.

Developmental origins of cardiometabolic health outcomes in twins: A systematic review and meta-analysis

BACKGROUND AND AIMS

Studies of twins can reduce confounding and provide additional evidence about the causes of disease, due to within-pair matching for measured and unmeasured factors. Although findings from twin studies are typically applicable to the general population, few studies have taken full advantage of the twin design to explore the developmental origins of cardiometabolic health outcomes. We aimed to systematically review the evidence from twin studies and generate pooled estimates for the effects of early-life risk factors on later-life cardiometabolic health.

METHODS AND RESULTS

An initial search was conducted in March 2018, with 55 studies of twins included in the review. Risk of bias was assessed using the Newcastle-Ottawa Scale, and eligible studies were included in a meta-analysis, where pooled estimates were calculated. Twenty-six studies analysed twins as individuals, and found that higher birthweight was associated with lower SBP (β = -2.02 mmHg, 95%CI: -3.07, -0.97), higher BMI (β = 0.52 kg/m², 95%CI: 0.20, 0.84) and lower total cholesterol (β = -0.07 mmol/L, 95%CI: -0.11, -0.04). However, no associations were reported in studies which adjusted for gestational age. Few of the included studies separated their analyses into within-pair and between-pair associations.

CONCLUSIONS

Early-life risk factors were associated with cardiometabolic health outcomes in twin studies. However, many estimates from studies in this review were likely to have been confounded by gestational age, and few fully exploited the twin design to assess the developmental origins of cardiometabolic health outcomes.

Early Life Adversity with Height Stunting Is Associated with Cardiometabolic Risk in Adolescents Independent of Body Mass Index

OBJECTIVE

To evaluate cardiovascular and metabolic function in youths adopted internationally from orphanages/institutions (postinstitutionalized) who were height-stunted at adoption.

STUDY DESIGN

A total of 30 postinstitutionalized youths (age, 9-18 years; body mass index [BMI] percentile, 7.2-90.4) who were height-stunted at adoption were compared with age- and BMI percentile-matched youths (n = 90). Measurements included total body fat and visceral adipose tissue (dual radiograph absorptiometry), arterial stiffness (augmentation index and pulse wave velocity), cardiac autonomic function (heart rate variability), blood pressure, and fasting lipid, glucose, and insulin levels. Linear regression analyses were computed controlling for parent education, age, trunk tissue fat, height-for-age, sex, and race.

RESULTS

Compared with controls of the same age, sex, and BMI, the postinstitutionalized children had higher systolic blood pressure (P = .018), augmentation index (P= .033), total cholesterol (P= .047), low-density lipoprotein cholesterol (P= .03), triglycerides (P= .048), insulin (P= .005), and HOMA-IR (P= .01) values. The postinstitutionalized children had a lower low-frequency to high-frequency ratio (P = .008), indicating lower sympathetic tone, as well as a lower total lean mass (P = .016), a lower gynoid lean mass (P = .039), and a higher proportion of trunk tissue fat (P = .017). The postinstitutionalized and control children did not differ in any other body composition measures.

CONCLUSIONS

Early life stress, as represented by height-stunted growth in institutional care, may be associated with early pathways to cardiovascular and metabolic risk in youths even after moving into well-resourced homes early in life and in the absence of increased adiposity. These findings suggest that postinstitutionalized youths with a history of height stunting may need to be closely monitored for emergent cardiometabolic risk factors.

Infant Weight and Length Growth Trajectories Modeled Using Superimposition by Translation and Rotation Are Differentially Associated with Body Composition Components at 3 and 7 Years of Age

OBJECTIVE

To evaluate how infant weigh and length growth trajectories associate with body composition at 3 and 7 years because previous studies have noted that rapid infant weight gain increases risk for high body mass index (BMI) in children.

STUDY DESIGN

There were 322 children enrolled at 3 years of age with dual x-ray absorptiometry body composition data and pediatrician growth data for 0-2 years of age who were included in analysis. Superimposition by translation and rotation modeling was used to characterize infant weight and length trajectories in terms of size, tempo and velocity measures. Associations of these measures with fat mass, lean mass, percent body fat, bone mineral content, BMI z-score, and overweight prevalence at 3 and 7 years of age were determined.

RESULTS

Infant growth trajectories differed by sex, race, and breastfeeding status. Higher overall weight size and weight velocity from 0 to 2 years of age were associated positively with all age 3 body composition and anthropometry outcomes. However, longer length size from 0 to 2 years of age was associated independently with higher bone mineral content and lean mass, but lower percent body fat, BMI z-score, and a lower odds of overweight at 3 years of age. By 7 years of age, later than average infant weight tempo was also associated with lower fat mass, lean mass, and BMI z-score.

CONCLUSIONS

Greater average weight size and greater weight velocity in infancy are markers for greater overall body size at 3 and 7 years of age. However, longer average lengths and later weight gain tempo between 0 and 2 years of age may help to establish a leaner body composition by 3 and 7 years of age.

Variation in the relationship between birth weight and subsequent obesity by household income

There is evidence to suggest that high birth weight increases subsequent BMI. However, little attention has been paid to variations in this impact between population groups. This study investigates the relationship between high birth weight and subsequent obesity, and whether or not this relationship varies by household income. Data was taken from fourteen rounds of the Health Survey for England (between 2000-2014; N = 31,043) for children aged 2-16. We regressed obesity in childhood against birth weight, accounting for interactions between birth weight and household income, using sibling-fixed effects models. High birth weight was associated with increased risk of subsequent obesity. This association was significantly more pronounced in children from low-income families, compared with children from high-income families. A 1 kg increase in birth weight increased the probability of obesity by 7% in the lowest income tertile and 4% in the highest income tertile. This suggests that early socioeconomic deprivation compound the effect of high birth weight on obesity.

Association between birthweight and later body mass index: an individual-based pooled analysis of 27 twin cohorts participating in the CODATwins project

Background

There is evidence that birthweight is positively associated with body mass index (BMI) in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment. We analysed the association between birthweight and BMI from infancy to adulthood within twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

Methods

This study is based on the data from 27 twin cohorts in 17 countries. The pooled data included 78 642 twin individuals (20 635 monozygotic and 18 686 same-sex dizygotic twin pairs) with information on birthweight and a total of 214 930 BMI measurements at ages ranging from 1 to 49 years. The association between birthweight and BMI was analysed at both the individual and within-pair levels using linear regression analyses.

Results

At the individual level, a 1-kg increase in birthweight was linearly associated with up to 0.9 kg/m2 higher BMI (P < 0.001). Within twin pairs, regression coefficients were generally greater (up to 1.2 kg/m2 per kg birthweight, P < 0.001) than those from the individual-level analyses. Intra-pair associations between birthweight and later BMI were similar in both zygosity groups and sexes and were lower in adulthood.

Conclusions

These findings indicate that environmental factors unique to each individual have an important role in the positive association between birthweight and later BMI, at least until young adulthood.

Social and somatic determinants of underweight, overweight and obesity at 5 years of age: a Norwegian regional cohort study

OBJECTIVE

To identify associations between the weight groups underweight (UW), overweight (OW) and obesity (OB) at 5 years of age and exposures related to pregnancy, anthropometric measures at birth, sociodemographic factors, and family health, anthropometric measures and habits.

DESIGN

Regional cohort study.

SETTING

Oppland County, Norway.

METHODS

Pregnancy data were obtained from a prospective perinatal register for children born in the county, and weight and height were measured by midwives at birth and by public health nurses at 5 years. Other information was obtained from questionnaires completed by parents.

PARTICIPANTS

Of 1895 eligible children, current weight and height were obtained for all, weight and length at birth and information from parents for 1119 (59%) and pregnancy register data for 749 (40%) of the children. The significance of potential explanatory variables from descriptive statistics was tested in multinomial logistic regression analysis.

RESULTS

The prevalence of UW, OW and OB among participants was 7.8%, 10.6% and 3.5%, respectively. UW was associated with anthropometric measures at birth and those of parents, but not with sociodemographic or behavioural characteristics. OW and OB were associated with anthropometric measures of parents and siblings and with a variety of unfavourable social characteristics, lack of prolonged breast feeding, sedentary behaviour and dental caries, but not with current dietary habits. After adjustments, OW and OB were marginally related to birth parameters and diet and unrelated to physical activity, but significantly related to parental body mass index, low parental education and maternal smoking.

CONCLUSION

The strong associations between sociodemographic and behavioural factors and OW and OB, but not with UW, may suggest that environmental factors are major contributing causes of OW and particularly OB at 5 years. These results may be helpful in targeting preventive measures against OW and OB.

Early growth faltering in post-institutionalized youth and later anthropometric and pubertal development

BackgroundEarly-life adversity that increases the risk of growth stunting is hypothesized to increase the risk of obesity and, in girls, early-onset puberty. This hypothesis was tested in children adopted from orphanages.MethodsPost-institutionalized (PI) youth were compared with youth reared in comparable families (non-adopted; NA) on height, weight, pubertal stage, and fat mass (127 PI, 80 female; 156 NA, 85 female, aged 7-14 years). Anthropometric findings at adoption were obtained from first US clinic visits.ResultsOverall, 25% of PI youth were height-stunted (<3rd percentile) at adoption. Years post adoption, PI youth had lower BMI-for-age (P=0.004), height-for-age (P<0.001), and less body fat (P<0.001) than NA youth had, but they did not differ by sex. Pubertal status did not differ by group or sex. The anthropometric findings held when the stunted-at-adoption subset was examined; they were also less likely to be in central puberty than other PI youth.ConclusionEarly deprived orphanage care increases the risk of growth stunting but not obesity in children adopted into US families, and it does not independently contribute to early-onset puberty for PI girls. The role of the environment following early adversity may modify the impact of early adverse care.

Impact of placental insufficiency on fetal skeletal muscle growth

Intrauterine growth restriction (IUGR) caused by placental insufficiency is one of the most common and complex problems in perinatology, with no known cure. In pregnancies affected by placental insufficiency, a poorly functioning placenta restricts nutrient supply to the fetus and prevents normal fetal growth. Among other significant deficits in organ development, the IUGR fetus characteristically has less lean body and skeletal muscle mass than their appropriately-grown counterparts. Reduced skeletal muscle growth is not fully compensated after birth, as individuals who were born small for gestational age (SGA) from IUGR have persistent reductions in muscle mass and strength into adulthood. The consequences of restricted muscle growth and accelerated postnatal "catch-up" growth in the form of adiposity may contribute to the increased later life risk for visceral adiposity, peripheral insulin resistance, diabetes, and cardiovascular disease in individuals who were formerly IUGR. This review will discuss how an insufficient placenta results in impaired fetal skeletal muscle growth and how lifelong reductions in muscle mass might contribute to increased metabolic disease risk in this vulnerable population.

[Weight/head circumference ratio at birth for assessing fetal growth]

The objective of this study was to use weight/head circumference ratio at birth to assess fetal growth. A retrospective cohort study was conducted in Zona da Mata, Pernambuco State, Brazil, with 915 term infants. Infants' anthropometric measurements and data on prenatal care, smoking during pregnancy, family income, and maternal schooling and nutritional status were collected in the first 24 hours after birth. Infants were classified as proportionate (weight/head circumference ratio ≥ 0.90) versus disproportionate (< 0.90). Lower mean weight/head circumference ratio was associated with maternal smoking, younger age, inadequate prenatal care, and low BMI, height, and triceps skinfold thickness. Mean weight, length, head and chest circumference, arm circumference, and triceps skinfold thickness were lower among infants with disproportionate weight/head circumference ratio, independently of sex. In conclusion, weight/head circumference ratio and birth weight are important indicators of fetal growth.

Twin studies advance the understanding of gene–environment interplay in human nutrigenomics

Investigations into the genetic architecture of diet–disease relationships are particularly relevant today with the global epidemic of obesity and chronic disease. Twin studies have demonstrated that genetic makeup plays a significant role in a multitude of dietary phenotypes such as energy and macronutrient intakes, dietary patterns, and specific food group intakes. Besides estimating heritability of dietary assessment, twins provide a naturally unique, case–control experiment. Due to their shared upbringing, matched genes and sex (in the case of monozygotic (MZ) twin pairs), and age, twins provide many advantages over classic epidemiological approaches. Future genetic epidemiological studies could benefit from the twin approach particularly where defining what is ‘normal’ is problematic due to the high inter-individual variability underlying metabolism. Here, we discuss the use of twins to generate heritability estimates of food intake phenotypes. We then highlight the value of discordant MZ pairs to further nutrition research through discovery and validation of biomarkers of intake and health status in collaboration with cutting-edge omics technologies.

Childhood obesity in low- and middle-income countries

Overweight and obesity in childhood is an increasing problem for the less affluent countries of the world. The prevalence of overweight/obesity varies, not only between countries but across countries, depending on the environments in which children live. Changes in physical activity and diet are having adverse effects on children's nutrition. Greater affluence and urbanisation with more technology such as television in homes are associated with overweight. Affluence also brings the ability to purchase commercial, prepared 'fast-food' items, leading too often to disadvantageous effects on children's diets. The solutions to this rising tide of overweight/obesity seem to lie with broad-based programmes initiated at central government level or at more local community level but which are designed to reach across and throughout societies to enable families and communities to modify the unhealthy lifestyle which too often accompanies increasing affluence and development.

Maternal distress in early life predicts the waist-to-hip ratio in schoolchildren

We report on life course stress determinants of overweight in children, using data from the longitudinal follow-up of the nested case-control arm of the SAGE (study of asthma genes and the environment) birth cohort in Manitoba, Canada. Waist and hip measurements were obtained during a clinic visit at age 9-11 years. Multiple linear regression was conducted to determine the relationship between the waist-to-hip ratio and maternal smoking during pregnancy, postpartum maternal distress and stress reactivity in children (cortisol, cortisol-DHEA [dihydroepiandrostrenone] ratio quartiles) following a clinic stressor at age 8-10 years. We found waist-to-hip risk at age 9-11 years to be elevated among boys and girls whose mothers had experienced distress in the postnatal period. This association varied by gender and asthma status. In healthy girls, postpartum distress increased waist-to-hip ratio by a factor of 0.034 (P < 0.01), independent of the child's stage of puberty and adrenarche, cortisol-DHEA ratio and duration of exclusive breastfeeding. Among girls with asthma, maternal smoking during pregnancy was associated with an increased waist-to-hip ratio, if the mother also experienced distress in the postpartum period (0.072, P = 0.038). Among asthmatic boys, an association between maternal distress and waist-to-hip ratio was evident at the highest cortisol-DHEA ratios. Stress-induced changes to leptin and infant over-eating pathways were proposed to explain the postnatal maternal distress effects. Drawing on the theories of evolutionary biology, our findings underscore the significance of postnatal stress in disrupting hypothalamic-pituitary-adrenal axis function in infants and increasing risk for child overweight.

Gestational weight gain in twin pregnancies and maternal and child health: a systematic review

Our objective was to systematically review the data interrogating the association between gestational weight gain (GWG) and maternal and child health among women with twin gestations. We identified 15 articles of twin gestations that studied GWG in relation to a maternal, perinatal or child health outcome and controlled for gestational age at delivery and prepregnancy body mass index. A positive association between GWG and fetal size was consistently found. Evidence on preterm birth and pregnancy complications was inconsistent. The existing studies suffer from serious methodological weaknesses, including not properly accounting for the strong correlation between gestational duration and GWG and not controlling for chorionicity. In addition, serious perinatal outcomes were not studied, and no research is available on the association between GWG and outcomes beyond birth. Our systematic review underscores that GWG in twin gestations is a neglected area of research. Rigorous studies are needed to inform future evidence-based guidelines.

Sleep duration and adiposity in older adolescents from Otago, New Zealand: relationships differ between boys and girls and are independent of food choice

Background

While relationships between sleep and BMI have been extensively studied in younger children the effect of sleep duration on adiposity in adolescents, who are undergoing rapid growth periods, is less well known. There is also a lack of consistent evidence on the role of sleep on other measures of adolescent body composition which may be more reflective of health than BMI in this age group. Previous research investigating whether these relationships differ between sexes is also inconsistent. Therefore the objective of this study was to investigate relationships between sleep duration and multiple body composition measures in older adolescents and to investigate if these relationships differ between boys and girls.

Methods

A web-based cross-sectional survey and anthropometric measurement of 685 adolescents (mean age 15.8 years) from 11 schools in Otago, New Zealand. Height and weight were measured by trained researchers and fat mass and fat-free mass were estimated using bio-impedance. Generalised estimating equations were used to examine associations between sleep duration and the following body composition measures: BMI, waist circumference (WC), waist-to-height ratio (WHtR), fat mass index (FMI), and fat-free mass index (FFMI). Analyses were adjusted for ethnicity, deprivation, the number of screens in the bedroom and fruit and vegetable consumption.

Results

When data from all participants were analysed together, no significant relationships were seen between sleep duration and any body composition measure but significant sex interactions were seen. An hour increase in average nightly sleep duration in boys only was associated with decreases of 1.2% for WC, 0.9% for WHtR, 4.5% for FMI and 1.4% for FFMI in multivariate models. Similar results were seen for weekday and weekend night sleep duration.

Conclusions

Sex specific factors may play a role in relationships between sleep and body composition in older adolescents. The results in boys were most pronounced for FMI, a measure of total adiposity, which suggests that insufficient sleep in adolescent boys may affect fat mass more than lean mass and that the use of measures such as BMI may result in an under-estimation of relationships.

Dieting status influences associations between dietary patterns and body composition in adolescents: a cross-sectional study

Background

Associations between food choice and body composition in previous studies of adolescents have been inconsistent. This may be due to the body composition measures used, or these associations may be affected by the dieting status of adolescents. The objective of this study was to investigate the association between dietary patterns and body composition in adolescents, and determine if these associations are moderated by dieting status.

Methods

Information on food consumption and current dieting status was collected, using a web-based survey, in 681 adolescents (mean age 15.8 (SD 0.9) years) from schools in Otago, New Zealand. Non-dieters were defined as those reporting not being on a diet as they were “happy with their weight”. Principal components analysis (PCA) was used to determine dietary patterns. Body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), fat mass index (FMI), and fat-free mass index (FFMI) were examined as outcomes. Generalized estimating equations were used to examine associations between dietary patterns and body composition.

Results

PCA produced three dietary patterns: ‘Treat Foods’, ‘Fruits and Vegetables’, and ‘Basic Foods’. A standard deviation increase in ‘Basic Foods’ was associated with a 3.58% decrease in FMI (95%CI −6.14, -0.94) in the total sample. When separate sex analysis was undertaken significant negative associations were found in boys only, between the ‘Basic Food’ score and WC, WHtR, FMI, and FFMI, while the ‘Fruits and Vegetables’ pattern was negatively associated with FMI. Associations between ‘Treat Foods’ and BMI, WC, and WHtR in non-dieters were positive, while these associations were negative for all other participants.

Conclusions

Significant associations were found between dietary patterns and indices of both central and total adiposity, but not BMI. Therefore using only BMI measures may not be useful in this age group. Since our results were significant for boys and not girls, nutrition messages designed to prevent obesity may be particularly important for adolescent boys. As an interaction between dieting status and ‘Treat Foods’ existed, future studies should also explore the role of dieting when investigating food choice and body composition.

Independent relation of maternal prenatal factors to early childhood obesity in the offspring

OBJECTIVE

To examine the independent contribution of risk factors developing during pregnancy to subsequent risk of obesity in young children.

METHODS

We conducted a historical cohort study using data from electronic medical records of mothers and their 3,302 singleton offspring born between 2004 and 2007 at a community-based obstetric facility who attended a 4-year well visit at a pediatric practice network. The child's body mass index (BMI) z score at age 4 years was studied in relation to the mother's gestational weight gain, gestational diabetes mellitus, gestational hypertension or preeclampsia, and prenatal tobacco use. Institute of Medicine categories defined excess and inadequate gestational weight gain at term. Analysis of variance and multiple linear regression were used to test their independent relation to BMI.

RESULTS

Mothers were white (39%), African American (46%), and of Hispanic ethnicity (11%); 46% were privately insured. The association of net gestational weight gain with the child's BMI z score was significant after adjustment for prepregnancy maternal factors (P<.001); gestational diabetes mellitus, gestational hypertension, and tobacco use were not significant in adjusted models. Children of mothers with excess gestational weight gain had a higher mean BMI z score (P<.001) but a significant association was observed only for inadequate gestational weight gain after adjusting for prepregnancy BMI and other covariates. Prepregnancy BMI (P<.001), Hispanic ethnicity (P<.001), and being married (P<.05) were independently associated with increasing BMI z score of the offspring.

CONCLUSIONS

Preconception maternal factors had a greater influence on child obesity than prenatal factors. The gestational weight gain category was independently related to BMI z score of 4 year olds, but this association was significant only for mothers with inadequate gestational weight gain.

LEVEL OF EVIDENCE

II.

Need for early interventions in the prevention of pediatric overweight: a review and upcoming directions

Childhood obesity is currently one of the most prevailing and challenging public health issues among industrialized countries and of international priority. The global prevalence of obesity poses such a serious concern that the World Health Organization (WHO) has described it as a "global epidemic." Recent literature suggests that the genesis of the problem occurs in the first years of life as feeding patterns, dietary habits, and parental feeding practices are established. Obesity prevention evidence points to specific dietary factors, such as the promotion of breastfeeding and appropriate introduction of nutritious complementary foods, but also calls for attention to parental feeding practices, awareness of appropriate responses to infant hunger and satiety cues, physical activity/inactivity behaviors, infant sleep duration, and family meals. Interventions that begin at birth, targeting multiple factors related to healthy growth, have not been adequately studied. Due to the overwhelming importance and global significance of excess weight within pediatric populations, this narrative review was undertaken to summarize factors associated with overweight and obesity among infants and toddlers, with focus on potentially modifiable risk factors beginning at birth, and to address the need for early intervention prevention.

Prepregnancy body mass index and gestational weight gain in relation to child body mass index among siblings

There is increasing evidence that in utero effects of excessive gestational weight gain may result in increased weight in children; however, studies have not controlled for shared genetic or environmental factors between mothers and children. Using 2,758 family groups from the Collaborative Perinatal Project, the authors examined the association of maternal prepregnancy body mass index (BMI) and gestational weight gain on child BMI at age 4 years using both conventional generalized estimating equations and fixed-effects models that account for shared familial factors. With generalized estimating equations, prepregnancy BMI and gestational weight gain had similar associations with the child BMI z score (β = 0.09 units, 95% confidence interval (CI): 0.08, 0.11; and β = 0.07 units, 95% CI: 0.04, 0.11, respectively. However, fixed effects resulted in null associations for both prepregnancy BMI (β = 0.03 units, 95% CI: -0.01, 0.07) and gestational weight gain (β = 0.03 units, 95% CI: -0.02, 0.08) with child BMI z score at age 4 years. The positive association between gestational weight gain and child BMI at age 4 years may be explained by shared family characteristics (e.g., genetic, behavioral, and environmental factors) rather than in utero programming. Future studies should continue to evaluate the relative roles of important familial and environmental factors that may influence BMI and obesity in children.

The thin-fat phenotype and global metabolic disease risk

PURPOSE OF REVIEW

There has been a great deal of interest in the thin-fat phenotype evident in Asian Indians and its risk associations in the epidemic of noncommunicable chronic disease associated with it. The cause of this phenotype is probably related to lifestyle and environment; however, genotypic and epigenetic modifications in utero also have been considered.

RECENT FINDINGS

The thin-fat phenotype occurs when fat is added to an already thin frame. This may occur with rural-urban migration, when positive energy balance occurs in a migrating population who were predominantly thin and physically active to begin with. The role of the pre-existing skeletal muscle mass and its interaction with newly deposited fat must be considered. The thin-fat phenotype may be programmed during fetal growth, but the evidence for this phenomenon is still not completely clear. Finally, although there is increased chronic disease morbidity at lower BMI and younger age in south Asian populations, BMI-related mortality does not appear to follow this trend.

SUMMARY

At present, the weight of evidence appears to link the thin-fat phenotype to an environmental and lifestyle phenomenon occurring in previously thin people. This is particularly relevant in India, given the pace of transition over the last two decades.

Early growth patterns and long-term obesity risk

PURPOSE OF REVIEW

This review is an update on recent findings regarding early growth patterns and later obesity. These data are important because the potential programming of obesity in early life provides hope for new prevention strategies targeting early growth for long-term benefits.

RECENT FINDINGS

Recent findings regarding the association of childhood or adulthood obesity with fetal growth, gestational weight gain, maternal diabetes, or infancy weight gain are reviewed. Some related outcomes and potential mechanisms are also described. Most studies remain observational and confirm previous findings, but some intervention studies have begun to appear in the recent literature and support some, but not other, observed associations.

SUMMARY

Past and recent findings confirm the association of early growth patterns with obesity. However, causality must be demonstrated and safety must be established before translating these findings into public health recommendations.