New research published in Acta Paediatrica suggests that children who engage in outdoor play during their preschool years have a lower risk of developing obesity later in childhood.
The study included children born in Japan during two weeks in January and July 2001. Of 53 575 children born, 42 812 had data on outdoor play habits at age 2.5 years. In a survey, parents were asked, “Where do your children usually play (excluding home residences and daycare centres attended)?” Available options for answers included “in my garden or on the grounds of my apartment complex,” “in parks,” “in natural areas such as fields, forests, and beaches,” “on the street,” “in shrines and temples,” “in playgrounds in department stores and supermarkets,” “other,” and “don’t play anywhere but inside my home.” If one or more of the first five items were chosen, a child was considered to have exposure to outdoor play—this was the case for 91% of the children.
In follow-up surveys when the children were seven years old, 31 743 of 42 812 (74%) children had height and weight data, with 10% classified as overweight or obese.
Compared with children without exposure to outdoor play, children with outdoor play habits had 15% lower odds of being overweight or obese, after adjusting for other influencing factors.
“We suggest that parents and caregivers encourage outdoor play habits in their children at an early age, as this may help prevent obesity later in life,” said corresponding author Takahiro Tsuge, MPH, of Kurashiki Medical Center.
The foundation for healthy eating behaviour starts in infancy. Young children learn to regulate their appetite through a combination of biological, psychological, and sociological factors. In a new paper published in Social Science & Medicine, researchers at the University of Illinois Urbana-Champaign propose a model that explores these factors and their interactions, providing guidelines for better understanding childhood appetite self-regulation.
Appetite self-regulation is related to general self-regulation, but it specifically concerns an individual’s ability to regulate food intake, which affects healthy development and obesity risk. Children are born with a capacity to regulate appetite based on hunger and satiety signals, but with increased exposure to environmental factors, their eating is increasingly guided by psychological reasoning and motivations. Therefore, it is important to take a developmental perspective to trace changes in eating behaviours over time, Ju stated.
Ju and her colleagues provide a comprehensive framework based on the biopsychosocial pathways model, which outlines three interacting categories: Biological factors, including sensory experience, physiological hunger and satiety signals, brain-gut interaction, and the influence of the gut microbiome; psychological factors, including emotional self-regulation, cognitive control, stress regulation, and reward processing;and social factors, such as parental behaviour and feeding practices, culture, geographic location, and food insecurity.
The researchers combine this framework with temperamental theory to explore how the pathways are modified by individual temperament.
Children react differently to stimuli based on their psychological and emotional make up, Ju explained. For example, openness to novelty and positive anticipation can affect whether a child is willing to try new foods. If a parent pressures their child to eat, it could be counter-productive for a child with heightened sensitivity to negative affect, causing the child to consume less.
The model also takes children’s developmental stages into account. Infants have basic appetite regulation based on physiological cues. They gradually become more susceptible to external influences and by age 3-5, children begin to exhibit greater self-control and emotional regulation.
“By analysing the pathways outlined in our model, we can better understand the combined influences of multiple factors on children’s appetite self-regulation and their motivations to approach food,” Ju said. “For example, the presence of palatable food may not generate similar responses in everyone. Children could approach food as a reward, for pleasure-seeking, or to regulate emotions. The underlying motivations can be diverse, and they are influenced by external factors as well as temperamental characteristics.”
Socio-environmental influences include parent-child interactions around food, as well as non-food-related caregiver practices that can impact the child’s emotional regulation. The household food environment, cultural value of food intake, and food availability are also important factors, the researchers stated.
“If we understand the differential susceptibility to various factors, we can identify and modify the environmental influences that are particularly obesogenic based on children’s temperamental characteristics. Then we will be able to provide more refined approaches to support children’s healthy eating behaviour,” Ju explained.
Maternal obesity impacts the eating behaviours of offspring via long-term overexpression of the microRNA miR-505-5p, according to a study publishing June 4 in the open-access journal PLOS Biology by Laura Dearden and Susan Ozanne from the MRC Metabolic Diseases Unit, Institute of Metabolic Science, University of Cambridge, UK, and colleagues.
Previous studies in both humans and animal models have shown that the offspring of obese mothers have a higher risk of obesity and type 2 diabetes.
While this relationship is likely the result of a complex relationship between genetics and environment, emerging evidence has implicated that maternal obesity can disrupt the hypothalamus – the region of the brain responsible for nutrition sensing and energy homeostasis.
In animal models, offspring exposed to overnutrition during key periods of development eat more, but little is known about the molecular mechanisms that lead to these changes in eating behaviour.
In this study, researchers found that mice born from obese mothers had higher levels of the microRNA miR-505-5p in their hypothalamus – from as early as the foetal stage into adulthood.
The researchers found that the mice ate more and showed a preference for high-fat foods.
Interestingly, the effect of maternal obesity on miR-505-5p and eating behaviours was mitigated if the mothers exercised during pregnancy.
Cell culture experiments showed that miR-505-5p expression could be induced by exposing hypothalamic neurons to long-chain fatty acids and insulin, which are both high in pregnancies complicated by obesity.
The researchers identified miR-505-5p as a novel regulator of pathways involved in fatty acid uptake and metabolism, therefore high levels of the miRNA make the offspring brain unable to sense when eating high fat foods.
Several of the genes that miR-505-5p regulates have been associated with high body mass index in human genetic studies.
The study is one of the first to demonstrate the molecular mechanism linking nutritional exposure in utero to eating behaviour.
The authors add, “Our results show that obesity during pregnancy causes changes to the baby’s brain that makes them eat more high fat food in adulthood and more likely to develop obesity. Importantly we showed that moderate exercise, without weight loss, during pregnancies complicated by obesity prevented the changes to the baby’s brain. This helps us understand why the children of mothers living with obesity are more likely to become obese themselves, with early life exposures, genetics and current environment all being contributing factors.”
Children and young people who are overweight or obese are at significantly higher risk of iron deficiency, according to a study by nutritional scientists at the University of Leeds.
Researchers from the School of Food Science and Nutrition examined thousands of medical studies from 44 countries involving people under the age of 25 where levels of iron and other vitamins and minerals had been recorded alongside weight. They found that iron deficiency was associated with both underweight and overweight children and adolescents.
By contrast, zinc and vitamin A deficiencies were only observed in children who were undernourished, leading researchers to conclude that iron deficiency in overweight children is probably due to inflammation disrupting the mechanisms that regulate iron absorption.
The results of the research appear in the journal BMJ Global Health.
Iron deficiency in children has a negative effect on brain function, including attention, concentration and memory, and can increase the risk of conditions, such as autism and ADHD.
It is already recognised as a problem in adults living with obesity, but this research is the first to look at the association in children.
Lead author Xiaomian Tan, a Doctoral Researcher in the University of Leeds’ School of Food Science and Nutrition said: “The relationship between undernutrition and critical micronutrients for childhood growth and development is well established, but less is known about the risk of deficiencies in iron, vitamin A and zinc in children and adolescents who are overweight or obese, making this a hidden form of malnutrition.
“Our research is hugely important given the high prevalence of obesity in children. We hope it will lead to increased recognition of the problem by healthcare practitioners and improvements in clinical practice and care.”
Hidden hunger
Historically the problem has been linked to malnutrition and is a particular concern for lower- and middle-income countries where hunger may be the leading cause of mortality for young children.
Increasingly though it is being recognised that vitamin and mineral deficiencies can also occur in people who are overweight and obese and who have a nutrient-poor but energy-dense diet, something which has been described as ‘hidden hunger’.
In high-income countries it is associated with ultra-processed foods that are high in fat, sugar, salt, and energy but in lower- and middle-income countries obesity is often associated with poverty and monotonous diets with limited choices of staples such as corn, wheat, rice, and potatoes.
Many developing countries are now facing a double burden of malnutrition alongside overnutrition due to the rapid increase in the global prevalence of obesity in recent decades, especially in children aged between five and 19.
Undernutrition versus overnutrition
The research also highlights differences in focus between higher income countries and developing nations, with most studies in Africa and Asia focusing on undernutrition and those from North America and Europe focusing entirely on overnutrition.
The researchers say this is particularly concerning as both Africa and Asia are experiencing the highest double burden of malnutrition due to economic growth and the transition to a western-style high-sugar, high-fat diet.
Between the years 2000 and 2017, the number of overweight children under the age of five in Africa increased from 6.6 to 9.7 million, and in Asia that figure rose from 13.9 to 17.5 million. At the same time, there was an increase in the number of stunted children under 5, from 50.6 to 58.7 million in Africa.
Research supervisor Bernadette Moore, Professor of Nutritional Sciences in Leeds’ School of Food Science and Nutrition, said: “These stark figures underscore the fact that the investigation of micronutrient deficiencies in relation to the double burden of malnutrition remains critically important for child health.
“By the age of 11 here in the UK, one in three children are living with overweight or obesity, and our data suggests that even in overweight children inflammation leading to iron deficiency can be an issue.
“Iron status may be the canary in the coalmine, but the real issue is that prolonged inflammation leads to heart disease, diabetes and fatty liver.”
Increasing physical activity and improving diet have been shown to reduce inflammation and improve iron status in children and the researchers are now calling for further studies into the effectiveness of these interventions.
They also believe that more research is needed into micronutrient deficiencies and the double burden of malnutrition and overnutrition in countries where there are currently gaps in data.
A simple measure of obesity in children and adolescents that could replace body mass index (BMI) has been identified in a new study as waist circumference-to-height ratio. This measure detected excess fat mass and distinguished fat mass from muscle mass in children and adolescents more accurately than BMI. The study was conducted in collaboration between the University of Bristol in the UK, the University of Exeter in the UK, and the University of Eastern Finland, and the results were published in Pediatric Research.
The prevalence of childhood and adolescent obesity has reached an epidemic proportion and is affecting nearly 1 in 4 children in the current decade.
Unfortunately, obesity in the young population has been associated with cardiovascular, metabolic, neurological, musculoskeletal diseases and premature death in adulthood.
Accurately detecting overweight and obesity in children is critical to initiating timely interventions.
For nearly a generation, weight-to-height ratio charts and BMI for age and sex have been used to diagnose children with obesity.
However, these surrogate assessment tools are inaccurate in childhood and adolescence since they do not distinguish fat mass from muscle mass.For instance, two children with similar BMI might have different proportions of fat and muscle mass which makes obesity diagnosis difficult.
Expensive tools such as the dual-energy Xray absorptiometry (DEXA) scan accurately measures fat and muscle content of the body, but this device is not readily available in primary health care centres.
Recently, the American Academy of Pediatrics (AAP) published a clinical guideline on childhood obesity and requested urgent research on inexpensive and accurate alternative measures of obesity.
Emerging studies in adults appear to suggest that waist circumference-to-height ratio predicts premature death better than BMI and could be a potential added tool to BMI measure in improving the diagnosis of obesity.
However, there has been no former evaluation of how much waist circumference-to-height ratio measurements agree with DEXA-measured fat mass and muscle mass during growth from childhood to young adulthood.
In addition, the threshold of waist circumference-to-height ratio needed to detect excess fat in children is not clear, hence this study.
The current study is the largest and the longest follow-up DEXA-measured fat mass and muscle mass study in the world using the University of Bristol’s Children of the 90s data (also known as the Avon Longitudinal Study of Parents and Children). The study included 7,237 children (51% females) aged 9 years who were followed-up until age 24 years.
Their BMI and waist circumference-to-height ratio were measured at ages 9, 11, 15, 17, and 24 years.
When different devices measure a variable with an exact resemblance, it is described as perfect agreement of the devices with a score of 100%. For example, two DEXA scans from different manufacturers would measure fat mass with a near-perfect agreement of 99 to 100%.
Waist circumference-to-height ratio had a very high agreement of 81 — 89% with DEXA-measured total body fat mass and trunk fat mass, but a low agreement with muscle mass (24 — 39%). BMI had a moderate agreement with total fat mass and trunk fat mass (65 — 72%) and muscle mass (52 — 58%). Since BMI had a moderate agreement with DEXA-measured muscle mass, it is difficult to specify whether BMI measures excess fat or muscle mass.
The optimal waist circumference-to-height ratio cut points that predicted the 95th percentile of total fat mass in males was 0.53 and 0.54 in females.
This cut point detected 8 out of 10 males and 7 out of 10 females who truly had excess DEXA-measured fat.
The cut point also identified 93 out of 100 males and 95 out of 100 females who truly do not have excess fat.
“This study provides novel information that would be useful in updating future childhood obesity guidelines and policy statements. The average waist circumference-to-height ratio in childhood, adolescence, and young adulthood is 0.45, it does not vary with age and among individuals like BMI. Waist circumference-to-height ratio might be preferable to BMI assessment in children and adolescent clinics as an inexpensive tool for detecting excess fat. Parents should not be discouraged by the BMI or weight of their children but can inexpensively confirm whether the weight is due to increase in excess fat by examining their kid’s waist circumference-to-height ratio,” says Andrew Agbaje, an award-winning physician and pediatric clinical epidemiologist at the University of Eastern Finland.
Children fall broadly into four eating categories, according to new research at Aston University, and parents feed their children differently depending on those categories.
The four categories identified by Dr Abigail Pickard and the team in the School of Psychology are ‘avid’, ‘happy’, ‘typical’, and ‘fussy’. The results, which showed specific temperaments and carer feeding patterns associated with overeating, are published in the journal Appetite.
In the UK, around a fifth of children are overweight or obese when they begin school, rising to around a third by the time they leave primary school at age 11. The team sought to identify eating behaviour patterns and how these are associated with temperament, feeding practices and food insecurity, as a way to predict which children are more at risk of becoming overweight.
Typical eaters made up 44% of the children in the study, while fussy eaters accounted for 16%. But of greatest interest to the team was that around one in five young children in the study were found to show “avid eating,” including greater enjoyment of food, faster eating speed, and weaker sensitivity to internal cues of ‘fullness’. The behaviours that distinguish children with avid eating from those who show ‘happy’ eating (17.7% of children in the study), who have similarly positive responses to food, are wanting to eat (or eating more) in response to the sight, smell or taste of palatable food, and a higher level of emotional overeating. In combination, these eating behaviours can lead to overeating and subsequent weight gain.
Dr Pickard and the team have also shown that there are significant differences in children’s temperament and caregivers’ feeding practices between each of the four eating behaviour patterns. Children with avid eating are more likely to be active and impulsive, and their caregivers are more likely to give them food to regulate their emotions or to restrict food for health reasons. Children with avid eating were also less food secure than children who showed happy or typical eating behaviours.
Principal investigator of the project, Professor Jackie Blissett, said: “Whilst feeding practices are key intervention targets to change children’s eating behaviour and child weight outcomes, there has been little evaluation of how feeding practices interact with children’s food approach behaviours to predict eating behaviour.”
She explained that despite the knowledge of the influence of feeding practices on children’s weight, current public health advice is generic and does not reflect variability in children’s appetites. Parents and caregivers can be left feeling frustrated when trying to manage their child’s food intake. By defining the four eating behaviour profiles, this research project, which is funded by the Economic and Social Research Council and co-developed by Professor Claire Farrow, Dr Clare Llewellyn, Dr Moritz Herle, Professor Emma Haycraft and Dr Helen Croker will make it easier to identify the best feeding practices for each eating pattern and provide tailored, effective advice for parents.
Dr Pickard said: “Parents can use this research to help them understand what type of eating pattern their child presents. Then based on the child’s eating profile the parent can adapt their feeding strategies to the child. For example, children in the avid eating profile may benefit more from covert restriction of food, i.e., not bringing snacks into the home or not having foods on display, to reduce the temptation to eat foods in the absence of hunger. Whereas, if a child shows fussy eating behaviour it would be more beneficial for the child to have a balanced and varied selection of foods on show to promote trying foods without pressure to eat.”
The team has planned further research investigating avid eating behaviour and will invite the caregivers and their children into the specialist eating behaviour lab at Aston University to get a better picture of what avid and typical eating behaviours look like in a real-life setting. All the findings will be integrated and the researchers will work with parents to develop feasible and helpful feeding guidelines to reduce children’s intake of palatable snack foods.
As childhood obesity increases the world, children are entering puberty earlier and earlier – particularly girls. According to a survey, the onset of puberty occurs on average three months earlier for girls in every decade since 1977. Early, or precocious, puberty can leave children with psychological and social problems, as well leading to shorter adult heights. Studies also suggest that early puberty can increase the risk of developing cancer, diabetes, depression and cardiovascular disease later on in life.
While a scientific explanation has been lacking, the link between childhood obesity and early puberty has long been apparent. The more body fat a child has, the greater their likelihood of beginning puberty at an earlier age. Now, researchers have found what may be part of the answer in Drosphila fruit flies, publishing their results in Current Biology.
“Cholesterol is a fat. So, if you’re overweight, your body fat harbours more cholesterol. And it turns out that higher cholesterol is a key to earlier maturation in the fruit fly, our model organism. Our results demonstrate that the amount of cholesterol in adipose tissue and in certain support cells in the brain affects the growth of fruit flies and controls when they reach maturity,” explains Professor Kim Rewitz, a lead author of the study.
He adds, “And because the systems in fruit flies and humans are remarkably similar, we believe that the same may apply to humans – ie, that cholesterol in adipose tissue may help explain the connection between childhood obesity and early puberty.”
Puberty at ‘critical weight’
Professor Rewitz and the University of Copenhagen’s Department of Biology research team tested their hypothesis by putting fruit fly larvae on a “fatty diet” of cholesterol-packed foods. The development of these larvae was compared with larvae on a normal diet.
“We observed that larvae on the cholesterol diet consistently grew faster and entered ‘puberty’ sooner. It turned out that the increase of cholesterol stored in the fruit flies’ body fat and support cells in the brain increases the release of growth hormones that cause the animals to grow faster. Growth and size is a signal to the body for when to trigger puberty,” says Kim Rewitz.
The professor explains that in fruit flies, the signal to undergo maturation is when their weight and amount of body fat reach a certain point during development:
“In one way or another, animals need to know when they’re large enough to reach sexual maturity and be able to reproduce. Organisms have a checkpoint in their development that they must pass to enter puberty known as ‘Critical Weight’. This checkpoint is found in fruit flies and most likely in humans too. This means that both fruit fly larvae and children probably need to reach a certain body size and have a certain amount of fat stored to enter puberty. What we’ve found is that the amount of cholesterol stored in body fat plays an important role in this process.
“We see that fruit flies have a mechanism that senses how much cholesterol is stored in their body fat and support cells in the brain. At a certain point, the system then sends a signal to the brain centres that triggers maturation by producing steroid hormones. In humans, these correspond to testosterone and oestrogen.”
However, it also means that if the amount of stored cholesterol increases, the organism can actually fail to estimate its overall size accurately, so that it hits the critical weight checkpoint earlier than it normally would:
“Because overweight children have more body fat, they will probably also have stored more cholesterol at an earlier point in their development. So, if our assumption that the same mechanism exists in humans holds true, it could help to explain early puberty in obese children,” says the researcher.
Cholesterol may influence cancer as well
Professor Rewitz concludes that with part of the puzzle in hand, scientists can search for more clues and treatment. In the meantime, lifestyle changes remain the best solution for childhood obesity.
Professor Rewitz and his research colleagues have now started to look deeper into the significance of the cholesterol mechanism for cancer development. Their research also shows that, via the same mechanism, cholesterol can activate cell growth that leads to cancer.
