How does birth weight affect adult obesity in a low resource context?
South Africa is experiencing rapid increases in weight gain across the entirety of its population. Obesity is rising in both males and females, across all ages and socioeconomic groups. Like many other low-middle-income countries, it is experiencing a double burden of malnutrition alongside these high obesity rates. Malnutrition is present in one quarter of children under the age of three, resulting in stunting.
This stunting has been reported to be associated with adulthood disease risk, including obesity. Researchers thus far have not been able to look at this relationship in a low-middle-income country in the same participants by following them from birth into early adulthood. The authors of this study were able to do this for the first time using the Birth to Twenty Cohort which is a longitudinal study of children born in 1990 in South Africa.
Authors found that relative weight gain from birth into adulthood was positively related to fat mass, including both visceral and subcutaneous fat in adulthood. Being stunted at age two was inversely associated with fat-free soft tissue mass (i.e. lean body mass) in adulthood. This finding is analogous to trends that have been shown across Brazil, Guatemala and India.
Read MoreWhat is driving rates of obesity in Chinese boys?
Over recent decades, alongside economic development, China has undergone a rapid nutrition transition that has resulted in a dramatic acceleration of obesity. Unlike other countries across the world, like the USA and UK, where childhood obesity rates have stabilised, the prevalence in China continues to worsen.
This crisis in China is also unique in terms of how it presents between genders. Dissimilar to other countries, obesity is higher in boys than girls. Boys are almost twice as likely to have obesity. Up until now, there has been limited evidence explaining why these unique sex differences have emerged.
Using a cross-sectional national health survey, Wang and colleagues revealed, as would be expected, that adolescent boys were much more likely to have energy intakes exceeding expectations. Importantly however, it found significantly different self-perceptions by sex, with boys much more likely to underestimate their weight and be satisfied with their current health behaviours.
These weight perceptions were supported by mothers, who were more accurate in predicting their daughter’s weight vs those with a son. Clearly, weight-related beliefs in China have a role to play in the increasing – and widening – rates of obesity in children.
Read MoreThe lasting impact of where we live
The neighbourhoods we live in influence how we behave and ultimately shape our health outcomes. Regardless of how much money an individual earns, if they live in a less-affluent neighbourhood evidence would tell us that they will have poorer health outcomes than if they lived in a more affluent neighbourhood. This effect is particularly strong when looking at obesity and diabetes.
While this has been long understood, little is known about when risk factors emerge in childhood and adulthood in individuals living in socioeconomically different neighbourhoods, and the cumulative effect of disadvantage over childhood. Researchers from Finland set out to answer this question through a population cohort, where participants were measured at repeated intervals for adiposity and behavioural risk factors. By linking postal codes to neighbourhood deprivation scores, researchers assessed the impact of living conditions on diabetes outcomes.
They found that detrimental lifestyle factors by neighbourhood living conditions are present right from childhood and worsen into adulthood. These risk factors accumulate over time to accelerate increased rates of obesity, hypertension and fatty liver by middle age.
Read MoreWhen do trends of inactivity begin?
Physical activity is important for both the current and future health of children. For a long time a belief has been held that children are adequately active with a dramatic decline in behaviour beginning from later adolescence into adulthood. This decline is much more significant in girls then in boys. Based on this understanding, for many years adolescent physical activity has been targeted by both national and international organisations. However, there has been a recent suggestion that declines in activity begin earlier than adolescence.
A group of researchers from Glasgow set out to determine when exactly changes in activity take place. They used a UK longitudinal cohort study from North-East England with data on participants across eight years. In physical activity research, questionnaires have shown to be highly unreliable and inaccurate, but they are often what is used in cohort studies as they are low cost. In this cohort, objective data using accelerometers (electronic monitors that record activity patterns across the day) were used at four separate years, making it a valuable resource to look at changes over time.
The researchers revealed that all trajectories of activity behaviour declined from seven years of age with no indication of a difference by gender. This analysis proves earlier understanding wrong and provides a strong case that policy and intervention efforts should begin well before adolescence.
Read MoreAntibiotic consumption and childhood obesity
A growing base of evidence suggests antibiotic use results in microbial disturbances in the gut. These disturbances in the microbiome may contribute to weight gain. In comparisons between individuals, it has been shown that those with obesity have a lower diversity of microbes in their gut. This research is supported by studies in animal models. In infancy, a baby’s microbiome is rapidly developing. It is thus suggested by some researchers that any antibiotic exposure in infancy may impede the establishment of the healthy gut microbiome and have lifelong metabolic consequences.
In a systematic review and meta-analysis, Miller and colleagues showed that the antibiotic use in infancy is indeed related to overweight and obesity in childhood. There were notable differences however by gender with boys appearing to be more affected by antibiotic use than girls.
The authors looked at multiple drugs finding that macrolides were most strongly related to increased obesity risk while narrow-spectrum drugs were not significantly associated. These researchers suggest in the fight against childhood obesity we need to examine antibiotic prescriptions and use across populations.
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