Obesity News Bulletin

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.

What 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.

The 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.

When 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.

Antibiotic 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.

Assessment of dietary patterns, physical activity and obesity among older US adults

Obesity in older adults results in premature declines in physical and mental health and cognitive functioning. Evidence shows that the incidence of obesity and chronic diseases are higher in rural areas than in urban areas. Furthermore, more older adults are concentrated in these rural areas. There is limited understanding of the behavioural factors driving increases in obesity in older adults in rural communities. Specifically, if differences in dietary behaviour between rural and urban settings contribute to elevated obesity rates. A study recently published in in PLOS One set out to firstly assess rural-urban differences in obesity rates in older adults, and secondly the relationship with dietary patterns.

Researchers used census data in a sample of respondents aged 65 years of age and above from the USA. Regression models were utilized to investigate if rural-urban disparities in obesity, and associations with risk factors of fruit consumption, green vegetable consumption and physical activity. The results revealed, consistent with earlier evidence, that obesity rates were highest in rural areas. In these rural areas, fruit consumption was the lowest. A negative association between obesity and fruit and green vegetable consumption was observed in urban but not rural settings. These findings illustrate the importance of considering urban-rural status when developing obesity prevention programs and strategies. Interventions need to address the unique barriers experienced between the two settings.

Predictors of weight gain in school children

Childhood obesity is a growing public health concern given the rising prevalence rates observed in both developed and developing countries. There are a multitude of health-related consequences that worsen into adulthood. Current estimates demonstrate that about 25% of children are overweight or obese. Given that obesity tracks into adulthood understanding why and how it emerges in early life is critical to developing effective preventative efforts.

In the European Journal of Clinical Nutrition, a recent analysis explored predictors of BMI change, overweight and obesity in school children. This was conducted in a prospective manner using a cohort of Irish school children 6-10 years of age. Height and weight were assessed objectively and lifestyle factors through a questionnaire with parents. These measurements were assessed five years apart at baseline and follow-up. Logistical regression models were then run by the researchers to understand the associations.

Initial BMI was the main predictor of subsequent overweight and obesity in schoolchildren, followed by the socioeconomic status of the school. Schools in disadvantaged areas had higher rates of obesity. Alongside this processed food consumption, lower levels of participation in sport clubs and low fruit intake was associated with higher levels of obesity. These findings illustrate the need for programmes aimed at preventing obesity with a focus on early years and disadvantaged communities.

Access to green space plays a role in the development of diabetes

Socioeconomic characteristics of the urban environments and neighbourhoods are associated with rates of obesity and type 2 diabetes. Access to green space within an individual’s residential area has been shown to be beneficial for health and well-being however, there is limited understanding of the relationship with type 2 diabetes. The aim of this study in the BMJ Open was to investigate the relationship between green space, body mass index (BMI) and type 2 diabetes.

The study examined this relationship in adults (25-74 years of age) in a large German city through the Dortmund Health Study. Researchers used geographical information systems to develop three indicators of green space: proportion of green space, available recreation area per person and distance to the next park or forest. Through regression analyses researchers demonstrated no association between green space and BMI. However, a lack of green space and further distance from parks or forests resulted in increased incidence of type 2 diabetes. The results suggest the availability of green space is an important part of the residential environment playing a role in the development of type 2 diabetes. It is essential to consider the built environment individuals live in when developing prevention plans and actions.

Childhood obesity inequalities in Britain are increasing over time

Across most high-income countries in the world socioeconomic inequalities in childhood obesity have been well documented. However, it is not clear how they have changed over time. Using Britain as an example, this study published in The Lancet, investigated how socioeconomic inequalities in childhood and adolescent weight, height, and BMI have changed over time.

The analyses demonstrated that from 1953 to 2015 socioeconomic associated inequalities in childhood obesity emerged and widened, while height differences became narrower. In 2001, at age 11 a there was a difference of 1.40 kg at the 50th weight percentile whereas a difference of 4.88 kg was observed at the 90th weight percentile. This finding that relative socioeconomic inequalities in obesity are worsening is consistent with other cross-sectional evidence including the UK’s national measurement program.

These significant changes show the impact of social changes on child and adolescent growth and development. The increasingly obesogenic environments in societies disproportionately affects disadvantaged children. These findings illustrate that the numerous policy initiatives implemented in Britain since 1991 have been insufficient and ineffective.

As these inequalities continue to widen there is clearly a need for new approaches to reduce differences in rates of childhood obesity between advantaged and disadvantaged populations. These trends are similar in many countries globally. Without effective interventions, inequalities seen in childhood and adolescence will continue to widen further throughout adulthood with significant health consequences.

Obesogenic factors and environments contributing to rising rates of obesity in Mexican children

Mexico has one of the highest youth obesity rates worldwide currently at 34% of all children and adolescents. This problem is rapidly worsening in Mexico with drastic consequences. There is limited understanding of the factors driving the rapidly increasing rates in Mexico. An understanding of determinants is critical to developing interventions, health programs and policies to effectively take on the crisis.

A recent review in Global Health Action set out to compile, describe, and analyse dietary conditions, physical activity, socioeconomic status, and cultural factors that create and exacerbate an obesogenic environment among Mexican youth. The authors approached this through a narrative review conducted across scientific databases and governmental reports.

The findings revealed a multitude of contributing factors including reduced healthy meal options at public schools, high rates of sedentary lifestyles among adolescents, lack of open spaces and playgrounds, socioeconomic deprivation, false or misunderstood sociocultural traditional beliefs, misconceptions about health, a high percentage of overweight or obese adults, and low rates of maternal breastfeeding. The factors identified are exacerbating the obesity problem in this population. From this evidence it is apparent that the average Mexican child is surrounded by a multitude of obesogenic factors driving rising rates of obesity. Measures to control these factors is drastically needed to stop continuation of the escalating rates.

Acute and Chronic Effects of Exercise on Appetite, Energy Intake, and Appetite-Related Hormones

The simple equation for obesity is Energy out < Energy in. The simplest way of increasing our ‘Energy out’, is to exercise more. However, the benefits of exercise extend beyond just calories, and in fact, it’s thought that exercise can improve subjective and homeostatic mediators of appetite in directions associated with enhanced meal-induced satiety. The degree to which this effect exists in an individual is highly variable and difficult to predict. This review, published in Nutrients, seeks to understand how adiposity, sex, and habitual physical activity modulate exercise-induced appetite, energy intake, and appetite-related hormone responses.

The review found that changes in perceptions of appetite, energy intake, and macronutrient composition in response to acute and chronic exercise stimuli are not modulated by levels of body adiposity or sex. However, in individuals with higher levels of habitual physical activity, they may exhibit improved sensitivity of the appetite control system through better compensatory adjustments for the energy content and density of food.

Although not conclusive, this paper draws attention to the benefits of exercise and need for an improved understanding of the individual factors that modulate appetite, appetite-related hormones, and food intake. Responses to exercise may help to explain the individual variability in body weight changes, and to facilitate the development of more efficacious weight management interventions.

A long-term maternal diet intervention to avoid the obesogenic effect in the offspring

The American Heart Association states that obesity among girls and women has generated a vicious cycle that contributes to the obesity epidemic. Studies into maternal overnutrition have found that high-fat diets in humans (which reflects the western diet), whereby the baby is exposed to over-nutrition during gestation, have increased risks of obesity, diabetes and other complications. In this study, published in The Journal of Nutritional Biochemistry, the diets of pregnant mice are varied to see whether they can prevent obesity related disease in the offspring, regardless of the weight-management of the mother.

The researchers transitioned the mice to normal fat (NF) diet 1 week, 5 weeks and 9 weeks before conception and continued this throughout gestation and lactation. After this, the offspring were given a high-fat diet for 12 weeks then sacrificed. They found that the mice whose parent had the NF diet for 9 weeks had a reduced risk of obesity, diabetes and other complications, regardless of maternal weight, suggesting a metabolic memory in the offspring that can be improved. Although the metabolic profiles of mice and humans are vastly different, the ease of access and economy of lifestyle interventions mean that a strategy to improve maternal diet for a period before conception, may be able to help prevent multi-generational obesity.

Eating faster is associated with general and abdominal obesity among Chinese children

Eating faster results in an increased rate of energy intake. However, the relationship between children’s eating speed, food intake and general abdominal adiposity is unknown, and forms the basis of this paper. A total of 50,037 Chinese children aged 7-17 years were enrolled from 7 provinces in China in 2013. Objective measurements of anthropometrics were taken and food speed was assessed by questionnaire.

There was a significant increasing trend across the slow, medium, and fast eating speed groups observed, in the prevalence of general obesity (7.2%, 10.0% and 15.9%), abdominal obesity (16.1%, 21.8%, and 29.4%) and waist-to-height ratio (WHtR) ≥ 0.5 (11.1%, 14.8%, and 22.0%). Compared with medium eating speed, fast eating speed was positively associated with obesity, abdominal obesity, and WHtR ≥ 0.5, while slow eating speed was negatively associated with these outcomes. They also found increased speed was associated with increased consumption.

Although this paper doesn’t tell us anything of the mechanism of this phenomenon, there are several biologically plausible suggestions. Such as, fast-eating leads to lower satiety and higher calorie intake, while slow-eating leads to enhanced thermic effect of food and also influences the release of gastrointestinal satiety hormones. More research should be done to see if it’s possible to change eating speed in adults, and whether this has any effect on obesity, as this could provide a simple non-invasive therapeutic target.

Impact of overweight, obesity and severe obesity on life expectancy of Australian adults

Obesity is known to significantly elevate the risk of many health problems, however its impact on life expectancy (LE) has not been quantified in Australia. This paper, published in the International Journal of Obesity, uses a microsimulation model of obesity progression to predict the changes in LE and years of life lost (YLL). It uses data on annual change in BMI based on age and sex, with Australian life-table data and published relative risk of all cause-mortality for different BMI categories. A nationally representative sample of 12,091 adults aged 20-69 were used.

The study predicted that the loss in LE for obese people to be 5.6-7.6 years and for severely obese people to be 8.1-10.3 years for men and women aged 20-29 years. If the baseline BMI was higher, so at age 20-29 BMI was above 25, years lost was greater. It also found that men lost 27.7% more years compared to women. In total, overweight and obesity was predicted to be responsible for 36.3 million YLL over the life course, with the severely obese contributing almost one-third of the life years lost despite comprising only 11% of the population.

This study does not take into account the impact that increased BMI has on quality-of-life, however evidence has shown there are significant impairments to health related quality-of-life for individuals at more severe levels of obesity as a result of co-morbidity and disability. This paper highlights the huge burden of disease in Australia, particularly in men, that needs to be addressed. The implication on the economy and the individual of 36.3 million YLL are too huge to ignore.

Analysis of the impact of rising food prices on obesity in women across 31 low and middle-income countries

In this longitudinal study, published in the International Journal of Obesity, the authors examine whether changes in food prices are associated with changes in obesity prevalence among women in developing countries, and assess the effect of individual socioeconomic status (SES). Anthropometric data, including BMI, and country-level food price inflation from low and middle income countries (LMIC) was used from 296,000 non-pregnant adult women, over the period 2000 to 2014.

The researchers found a strong link between food price inflation and obesity in adult women in LMICs, and the relationship is consistently modified by individual SES. Regardless of indicator used, higher food price inflation was positively associated with obesity among women in top SES categories, but was flat or negative among women in low SES categories, averaging over time. In lower SES groups it’s hypothesized that this is a result of a relative lack of exposure to food pricing, due to them growing their own food. Educational differences appeared the strongest of all SES measures which is consistent with the literature on social determinants of obesity.

This response to food budget constraints is recognised by other comparisons of LMICs, showing that individuals greatly reduce fruit and vegetable intakes as the relative cost increases [2], and that only those in the highest socioeconomic groups increase caloric intake in response to rising food prices. As the international burden of obesity grows, it’s important to understand how economic fluctuations translate into behavioural changes

Efficacy and safety of semaglutide for weight loss in patients with obesity

In this paper, published in The Lancet, the authors sought to assess efficacy and safety of the glucagon-like peptide-1 (GLP-1) analogue semaglutide, in comparison with a similar drug liraglutide, and placebo. The study was done in 8 countries, involving 71 clinical sites, with the primary endpoint being weight loss at week 52.

GLP-1 analogues mimic the function of human GLP-1, which regulates insulin secretion and glucagon secretion. These processes are linked with appetite, satiety and energy intake. This study found that these drugs, which were initially licensed for diabetes treatment, resulted in weight reductions which were significantly greater than the placebo group at 52 weeks. This weight loss is primarily due to the individuals consuming less energy, because of a combination of appetite suppression and enhanced satiety. Semaglutide was found to be the most effective, with weight loss of 11-14%, compared to Liraglutide’s 7-8%. In terms of side-effects, the most common complaint was of nausea. This was found to be dose dependent, so higher doses made side-effects more likely. Overall however, semaglutide was well tolerated, with no unanticipated safety or tolerability outcomes. Semaglutide has been shown to have a good benefit-risk profile which further supports its use as a weight management drug in its own right, instead of just being licensed for diabetes. Phase-3 studies are ongoing.