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Obesity, IQ and Parenting Styles

This is the second in a series of blogs, from Vircle, which explores the relationship between a child’s diet, schools and academic performance. Vircle is an ecosystem of child centred services aimed at making “food a foundation for a successful life”.

This first blog explored the link between school breakfast, nutrition and academic performance.

This blog explores the relationship between child obesity and IQ.

Early Childhood obesity linked to lower child IQ

Obesity is associated with lower cognition in adults. But what about children.

A recent study from Brown’s University in the US, analysed the relationship between the weight of early childhood children (first two years) and their cognitive abilities. The report discovered that “children on the threshold of obesity or overweight in the first two years of life had lower perceptual reasoning and working memory scores than lean children when tested at ages five and eight.”

The study comprised 233 children who had had early‐life weight and length/height measurements taken, which were then followed up with at least one measurement of cognitive abilities at age 5 or 8 years.

The children were placed into two groups – lean and non-lean.

The following graphs show the results of the study, which illustrates how different cognitive measurements correlate to weight-height scores (based on the WHO weight for height Z scoring standard).

The first graph clearly shows that children’s IQ was measured as lower if they had a higher WHO weight-for-height-Z scoring (non-lean body type when they were younger). The same pattern is observable for perceptual reasoning and working memory.

Figure 1. Weight‐for‐height z scores and children's full‐scale IQ, perceptual reasoning index, working memory index, and processing speed index at 5 or 8 years of age.

This study proposed a link between early-years weight and their IQ when they are in primary school. It also alluded to their being a link between obese children more likely to have lower IQ scores.

Sleep, Obesity and IQ

An interesting observation about the link between sleep and overweight is that children who sleep less are more likely to be overweight. A study of early childhood sleep found that those children who persistent short sleep from 2 years to 6 years were 4.2 times more likely to be overweight than those who slept 11 or more hours per night.

In another study of children with obstructive sleep apnea (OSA), it was found that those kids with obesity and OSA had much lower IQ scores than those with only OSA or those with no sleeping difficulties. The combination of OSA and obesity had a significant impact on child IQ. This study clearly showed that obesity can lead to higher cognitive impairments.

It is hard to say exactly what the connection between sleep and body weight is. However, it is known that overweight adults are more likely to suffer from obstructive sleep apnea, which can cause severe disturbances that prevent restful sleep.

While adults require around 8 hours sleep per night, children require more sleep than adults because they are growing so rapidly. It is recommended that school children get 10-11 hours sleep per night.

Poor sleep routines, can lead to overweight. The combination of a child being overweight and lacking in sleep increases the potential of a child having lower IQ.

A child’s relationship with food impacts cognitive ability

Children who are excessively overweight are found to have a range of impairments with the executive functions of the brain. Executive functions meaning - working memory, attention, mental flexibility, decision making, controlling impulses and delaying gratification.

It is found that obese children have lower ability to control impulses and have a reduced ability to resist gratification – especially when it comes to food. In short, Obese children are more sensitive to eating cues.

It is the parents at home that can have a significant impact on whether a child can develop the ability to control impulses and resist gratification. In doing so, they can help their children avoid becoming obese over the course of their lives.

One method of increasing a child’s ability to control impulses and resist gratification is the use of Inhibition training. These are activities, or exercises, which train the mind to develop greater inhibition. One such activity is that of no-go food. Where a child, or adult, is shown a selection of cards with images of food and trained to link no-go with unhealthy foods and go with healthy foods.

It is the training of a child’s habits that seems to be play a role in preventing poor food choices, and thereby reducing the risk of the child being overweight or obese. Some of the simplest actions appear to have the most significant impact, for example making fruit and vegetables accessible in the home, and keeping portion sizes smaller as opposed to larger.

The above two examples – no-go food training and making healthy food accessible in small portions are specific practices focused on developing good food habits in children.

But what about the role of general parenting styles and their impact on a child’s weight. The impact is huge.

Parenting Styles and child obesity and overweight

A study from Brown University (from 2008) showed that parenting style had a major impact on the chance of a child being overweight. Parenting styles can be categorised into four types, as shown in the below table, based on two variables – Expectations and support/warmth.

Children of authoritarian parents were found to be 5 times more likely to be overweight than authoritative parents. Parental warmth and sensitivity was shown to be related to greater intake of vegetables and fruits.


There is a link between obesity and IQ.

Children who are significantly overweight are more likely to have lower cognitive abilities – especially in the ability to control impulses and resist gratification. There is also a link between obesity and poor academic performance.

Parents can help their children reduce the risk of becoming obese and overweight by applying authoritative parenting styles and taking steps to train good food habits from an early age.

Vircle is focused on helping parents to nurture good food habits.

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