The harmful effects of obesity on the child‘s metabolic balance are well known, but much less so its impact on his/her cognitive functions. A recent American study looked at the beneficial effects of physical activity on both the fat mass and cognitive function of obese children, based on their weight before the tests. Here is an overview of its discoveries…

The link between obesity and cognitive functions


Obesity is a disease related to recent developments in our modern way of life: nearly 42 million children worldwide were overweight or obese in 2013, according to figures from the World Health Organization (WHO). As a result of an imbalance between calorie intake and expenditure, obesity is characterized by an inflation of reserves stored in the fatty tissue and generates numerous complications in terms of metabolism but also in terms of cognitive functions. One of the cognitive functions impacted is the regulation of conduct, including the ability to suppress inappropriate information and prioritize that allowing a correct answer to a given question.

New study assesses the effects of physical activity


Based on this finding, US researchers at the University of Illinois have evaluated the effects of 9-month controlled physical activity on the fatness and cognitive functions of obese children, based on their initial weight. In order to carry out their research, the scientists included in the study a cohort of 77 obese children aged 8 to 9 years that they divided into 2 groups:

  • The first group of 43 children had to follow a program of physical activities;
  • The second group of 34 children should not change their usual level of activity.

This cohort of 77 obese children was compared to that of 77 normal-weight children, similar in socio-economic status, parents’ educational level and intelligence test scores. Several parameters have been checked:

  • The ability to effort: through the measurement of oxygen consumption on a treadmill.
  • Inhibitory control (ability to inhibit irrelevant distractions): thanks to the Eriksen Flanker test.
  • Fat mass: via measurement of visceral and subcutaneous abdominal fat by dual energy x-ray absorptiometry.

Physical activity benefits on fat and cognitive functions


After 9 months of study, researchers found that visceral adipose tissue decreased in obese children during the physical activity program, while it increased in other children, especially in obese ones not included in the physical activity program. It is interesting to note the parallel between changes in visceral adipose tissue and those in cognitive performance, particularly with obese children subjected to physical exercise. In the latter, the smaller reductions in visceral fat were indeed related to significant improvements in performance on cognitive tests, regardless of total body fat.