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Learn the science behind the sources of this troubling trend, its sobering effects on children’s quality of life, and the steps you can take to help set up youth for lifelong health.

Originally published in the Winter 2020 issue of American Fitness Magazine

Lack of physical activity and an increase in sedentary behaviors are leading an overall upward trend in obesity, but the effects on children and adolescents are especially alarming. Today, obesity-associated disorders previously found only in adults—high blood pressure and type 2 diabetes, for example—are now commonly seen in children. Due to the prevalence of comorbidities linked to obesity and sedentary behaviors, the current generation of children may be the first in history to have a life expectancy shorter than that of their parents (AHA 2018).

Perhaps it is of little surprise, then, that childhood obesity is the primary concern among parents in the United States, surpassing both drug use and smoking (AHA 2018; IHRSA 2017). This may, in fact, be the reason parents bring their children to fitness professionals for help with adopting healthier habits in respect to nutrition and physical activity.

Since this special population brings with it special considerations, this article will go into greater detail on the specific effects of extra weight on children’s health and quality of life. It will also review some of the most common contributors to overweight and obesity in children—beyond a lack of good nutrition—and provide guidance on the steps that fitness professionals can take to begin turning the tide.


A 2018 report from the World Health Organization found that, in 2016, an estimated 41 million children under the age of 5 were diagnosed as overweight or obese—a 60% increase from 1990 (WHO 2018; Kelsey et al. 2014). In the United States, in fact, children are the fastest-growing subpopulation of individuals with obesity: 1 in 3 children is now considered overweight or obese (Nowicki et al. 2019).

Income and ethnicity also play a role. The prevalence is higher in lower-income households. Obesity rates in the African-American and Hispanic populations are 50%–75% higher than for Caucasians, whereas rates are 30% lower in the Asian population (also compared with Caucasians) (Nowicki et al. 2019).


Obesity during childhood can have a detrimental effect on quality of life in a variety of ways, leading to psychological, social and behavioral issues, as well as physical issues. For example, one study indicated that clinically overweight girls in kindergarten were 81% more likely to have behavior problems, possibly caused by the stigma associated with childhood obesity (Pulgarón 2013). Another study concluded that children who were overweight were more likely to be victims of bullying and discrimination (Bacchini et al. 2015).

Of course, like adults, children can also suffer from the physical outcomes of excess weight, such as high cholesterol, high blood pressure, metabolic syndrome and type 2 diabetes. What’s more, because children are still learning and growing, they experience additional issues related to having a high body mass index. For example, according to Nowicki et al., “The entire hormonal axis is affected in obese children, with complex interactions leading to not only growth differences but early pubertal differences as well.”

Here are some additional physical consequences associated with obesity and overweight in children:


A higher BMI and lack of physical activity are associated with increased risk for lower-extremity fractures, posture problems and alterations in bone metabolism, which can cause physiological changes to the growing skeleton. Specifically, increased body weight strongly affects attainment of peak bone mass (Nowicki et al. 2019). Nowicki and colleagues explain that these risks are significant because lifelong skeletal health can depend on maximizing bone mass accrual during childhood, and 40% of bone mineral accrual occurs within 2 years of the adolescent growth spurt.

Numerous studies have also documented an association between obesity and higher risk of musculoskeletal injuries, with risk rising as weight increases (Kessler et al. 2013). For example, children with obesity are 25% more likely to experience an extremity fracture (Dimitri 2019), and 2- to 5-year-olds who are considered “extremely obese” have more than double the fracture risk of children of normal weight (Nowicki et al. 2019). Fracture risk may be higher for children with obesity partly because they are more likely to fall—due to postural, balance and mobility limitations—and partly because they have difficulty in bracing against falls when they happen.


Obesity during childhood can greatly influence brain development, and researchers have argued that the excess weight is associated with cognitive dysfunction (Hagman et al. 2017; Mora-Gonzalez et al. 2019). The Mora-Gonzalez et al. study found that, during childhood, obesity is linked to detectable abnormalities in brain structure, such as decreases in brain regions associated with aspects of executive functioning—processes relating to “cognitive flexibility, inhibitory control, planning, working memory, and decision making, which are particularly important for the performance of daily activities, motor development and social relationships.” Normal-weight children show better performance in several of these areas, noted the researchers, who also hypothesized that undertaking high levels of physical activity may counteract obesity’s negative influence on brain and cognition. Cognitive function—especially the executive functions—matures around age 12, which demonstrates the importance of adequate physical activity before adolescence or adulthood (Bidzan-Bluma & Lipowska 2018).


Some researchers contend that children lacking regular physical activity are unable to develop their full potential in terms of motor skills (Bidzan-Bluma & Lipowska 2018). A literature review of children ages 4–6 revealed a reciprocal relationship between physical activity and motor development, highlighting that an increase in physical activity had significant beneficial effects in 80% of studies assessing motor skills and cognitive development (Zeng et al. 2017). Here again we see the importance of early childhood interventions.


Several factors play an etiological role in the world’s increasing childhood obesity rates. One of the most considerable is dietary behaviors: Both overeating and lack of nutritious food create conditions in which obesity and under-nutrition exist side by side (WHO 2019). There’s also mounting evidence that too little physical activity, too much sedentary activity, too much screen time and poor sleep habits—and the complex interaction of all of these factors—correlate with an elevated risk for obesity. Each of these factors will be explored below.


While physical activity has a wide range of benefits, lack of physical activity is the fourth leading cause of death worldwide (WHO 2010). Limited or no physical activity in children has been linked to various health problems beyond obesity, including posture and orthopedic problems, sleep conditions and mental health issues (Pulgarón 2013). Studies conducted to evaluate the key age for promoting healthy behaviors suggest that physical activity starts declining at age 7 and that healthy behaviors are stronger if established before grade 6 (Farooq et al. 2017; Lu & Montague 2016).

Considering this—and the fact that 80% of adolescents in the world fail to meet the WHO physical activity recommendation of 60 minutes per day—early childhood interventions should be a top priority (De Lyon, Neville & Armour 2017).


Physical activity and outdoor play used to be built into the daily lives of children. Today, however, the trend of earlier exposure to sedentary behaviors is on the rise. Although programming for an upsurge in youth physical activity is of great importance, inspiring a decrease in sedentary behaviors is equally crucial. Too much sedentary living has been shown to have detrimental effects on health, independent of physical activity level (Thivel, Chaput & Duclos 2018). So, even if children begin to comply with the recommended amount of physical activity per day, they will also need to decrease their sedentary time if they are to enjoy significant health improvements.


Screen time for media use and entertainment are contributing factors in the rise of childhood obesity, and children today are being introduced to screen time at very young ages. In 1970, children began watching regular TV at age 4. Now, the average age is closer to 4 months (Reid Chassiakos et al. 2016).

The Youth Risk Behavioral Survey from 2007 found that 35% of high school studen