Exercise has different effects on boys and girls.
The quantity of physical activity girls engage in and their body fat percentage are found to be unrelated in a new study. The results also show that boys’ sedentary behaviour increased two years later when their body fat percentage increased. The findings were published in International Journal of Obesity.
Multiple health advantages come from physical activity. However, boys and girls respond to exercise differently. The relationship between children’s physical activity and body fat was recently examined.
“We looked at the connection between objectively measured physical activity and the proportion of body fat in girls and boys,” says Silje Steinsbekk, a professor at NTNU’s (the Norwegian University of Science and Technology) Department of Psychology.
Instead of measuring people’s weight and height, the researchers evaluated body composition. They explored issues like: Does increasing physical activity eventually lead to a decrease in the percentage of body fat? Or is it feasible that those who have a higher rate of body fat over time become less active?
From the age of six to fourteen, the researchers examined the kids every two years. The amount of activity had different effects on the sexes, they found.
“In girls, we found no connection between their physical activity and amount of body fat. Increased physical activity didn’t lead to less body fat in the girls, and body fat had no effect on changes in their physical activity,” says Tonje Zahl-Thanem, a former research fellow and first author of the article.
For boys, it’s different, though. Their level of activity is influenced by their body fat.
“Increased body fat in boys led to less physical activity two years later, when they were 8, 10, and 12 years old,” says Zahl-Thanem.
Increased physical activity had no impact on increases in body fat, with one exception. Boys who are more physically active when they are 12 have a lower body fat percentage when they are 14. According to Steinsbekk, this wasn’t the situation early in the developmental process.
The researchers note that large bodies are heavier and require more work while exercising, which may explain why males whose body fat increases become less active over time. However, the study did not explore the reasons behind these disparities. Why, therefore, does it not apply to girls? Boys are often more physically active than girls, therefore when boys reduce their activity level, the bodily impact is larger, according to Steinsbekk. However, scientists can only conjecture on this.
We also know that children with larger bodies are less content with their bodies, and that for boys but not for girls, body dissatisfaction is linked to less physical activity. Boys’ physical activity is likely even more geared toward competition than that of girls, and having more body fat makes it harder to achieve.
According to Lars Wichstrm, a professor at NTNU’s Department of Psychology and study co-author, both of these factors may contribute to the reason why girls do not experience the same decline in physical activity that boys do. It’s also possible that females’ bodies and attractiveness receive greater attention, making them more likely to continue exercising as their body fat percentage rises.
The researchers also looked at the relationship between body fat and inactivity or a sedentary lifestyle. The amount of time the individuals spent sitting down during the day was also measured.
The findings indicate that boys who had higher body fat percentages two years later also had higher levels of sedentary behaviour. This held true across all age groups investigated, ranging from 6 to 14. In other words, males who have higher body fat percentages tend to be less active. But there was no connection here either for the girls. Over time, their level of inactivity was unaffected by their body fat percentage, and they did not become less active by obtaining more body fat.
“In sum, we found a link between physical activity, sedentary lifestyle, and fat percentage in boys, but not in girls,” Steinsbekk says.
Figures from the Trondheim Early Secure Study were used by the researchers (TESS). Since they were 4 years old, they followed approximately 1000 kids at intervals of two years. The eighth survey is currently being conducted, and the participants are now 18 years old.
The research team used data collected from the individuals at five distinct ages—6, 8, 10, 12, and 14—in this study. Data from the Trondheim Early Secure Study has been used in numerous research on the growth and health of kids.
Parvathy Sukumaran 
