Health Risks

The U.S. Department of Health and Human Services [HHS] recommends that children do 60 minutes (1 hour) or more of physical activity each day and that the bulk of this physical activity comes through aerobic exercise, such as walking and bicycling (2008a). For children and adolescents, regular physical activity helps build and maintain healthy bones and muscles, reduces the risk of developing obesity and chronic diseases, reduces feelings of depression and anxiety and promotes psychological well-being (HHS, 2008b).

Despite these benefits, many children are not getting adequate physical activity. In the 2014 United States Report Card on Physical Activity for Children and Youth, the National Physical Activity Plan Alliance reports that only 24.8 percent of youth ages 12-15 years obtain 60 minutes of moderate to vigorous physical activity every day (Dentro, 2014). During the school day, only 4 percent of elementary schools and 8 percent of middle/junior high schools provide daily physical education classes, and in 2012 only 58.9% of all school districts required that elementary schools provide students with regularly scheduled recess (Centers for Disease Control and Prevention [CDC], 2014). Unfortunately, less active children are more likely to be overweight, according to the American Academy of Pediatrics (2003).

What is Childhood Obesity?

  • Overweight is defined as a body mass index (BMI) at or above the 85th percentile and lower than the 95th percentile for weight.
  • Obesity is defined as a BMI at or above the 95th percentile for weight for children of the same age and sex.

Learn more about Childhood Overweight and Obesity from the CDC.

Overweight and Obesity on the Rise

When it comes to children's health, the costs of inadequate physical activity and poor eating habits are alarming. Inadequate physical activity and poor eating habits are major contributors to the increased rates of childhood obesity and overweight in the United States. Obese children are at least twice as likely to become obese adults. This puts obese children at greater risk for premature death and chronic diseases than their healthy-weight counterparts (American Academy of Pediatrics [AAP], 2003; CDC, 2015).

The following map shows the proportion of obese children ages 10–17 by state. The map is based on data from the 2011 National Survey of Children's Health (NSCH), which defines obesity as a BMI greater than the 95th percentile (Trust for America's Health and Robert Wood Johnson Foundation, 2013).


The negative health consequences of overweight and obesity include and chronic diseases, such as diabetes, heart disease, high blood pressure, respiratory problems and various cancer types. Other impacts include increased health care costs and lost productivity (CDC, 2012). Obese children and adolescents have a greater risk of social and psychological problems such as discrimination and poor self-esteem, as well as an increased risk of heart disease, stroke, Type II diabetes, sleep apnea, several types of cancer and osteoarthritis. In one study, 70% of obese children had at least one heart disease risk factor, such as high cholesterol or high blood pressure (CDC, 2015).

The growing obesity trend among adults is an alarming indication of what could happen to today's children. The following maps of the United States provide a portrait of the growth of obesity among U.S. adults since 1985. The maps show the percentage of U.S. adults in each state with a body mass index (BMI) of 30 or more, meaning they meet the medical definition of obesity for adults (CDC, 2014a).

Obesity Trends Among U.S. Adults: 1985
(BMI ≥ 30, or ~ 30 lbs overweight for 5’ 4” person)

Obesity Trends Among U.S. Adults: 1990
(BMI ≥ 30, or ~ 30 lbs overweight for 5’ 4” person)

Obesity Trends Among U.S. Adults: 1995
(BMI ≥ 30, or ~ 30 lbs overweight for 5’ 4” person)

Obesity Trends Among U.S. Adults: 2000
(BMI ≥ 30, or ~ 30 lbs overweight for 5’ 4” person)

Obesity Trends Among U.S. Adults: 2005
(BMI ≥ 30, or ~ 30 lbs overweight for 5’ 4” person)

Obesity Trends Among U.S. Adults: 2009
(BMI ≥ 30, or ~ 30 lbs overweight for 5’ 4” person)

Over the timeframe of the previous slides, obesity became recognized as a national health threat and a major public health challenge. In 2011, the Centers for Disease Control and Prevention (CDC), which creates these maps, changed their data collection methods. While we can’t compare the 2011 data to previous years, clearly obesity rates remain high. Note: The 1985 – 2010 data is not inaccurate. CDC made some changes to how data was collected and that change means that 2011 is not comparable with past years.

Obesity Trends Among U.S. Adults: 2011
(Obesity defined as BMI ≥ 30)

Obesity Trends Among U.S. Adults: 2013
(Obesity defined as BMI ≥ 30)

Developmental Health

While the physical health effects of obesity and lack of physical activity are becoming better understood, less is known about the impacts of the decline in walking and bicycling on child development. Adults, whose chief concerns pertain to children's health and safety, often forget that walking and bicycling to school may be a child's first chance to practice a little independence.

Some children today have less independence than their parents did, and this lack of independence can negatively impact their social behavior development (Huttenmoser, 1995). Driving a child from home to school limits the child's opportunities to interact with the neighborhood and other children. Questions also have been raised regarding how children who spend all their travel time in motor vehicles will master fundamental pedestrian and bicycling skills and what kind of drivers they will become because of their lack of experience negotiating traffic as walkers or bicyclists. Children who spend more time in supervised, structured activities have fewer opportunities to explore their neighborhoods. Children may lose some relatively safe opportunities to make decisions independently (Hillman, 1993).

Environmental Health

Less walking and bicycling and more motor vehicle traffic can negatively impact air quality. The trip to school can comprise 10 to 14 percent of the traffic volume on roads during school commute times (McDonald, Brown, Marchetti, & Pedroso, 2011), and nationally, passenger vehicles contribute the highest percentage of greenhouse gas emissions within the transportation sector (U.S. Environmental Protection Agency [EPA], 2015).

Children and adults with asthma are particularly sensitive to poor air quality. An average of one out of every ten school age children suffer from asthma, causing more than 10.5 million missed school days per year (EPA, 2014). The 1996 Olympics in Atlanta provided an opportunity to examine the relationship of traffic, air quality and health. During the 1996 Summer Games, Atlanta virtually banned single-occupant motor vehicles downtown in order to prevent gridlock. A study of the ban and its effects shows a clear relationship between traffic reduction and fewer incidents of asthma attacks that required medical attention. Researchers calculated a 42 percent decrease in asthma-related hospitalizations, emergency department visits and urgent care visits for children during the Olympics compared to the four weeks before and after the games (Friedman, Powell, Hutwagner, Graham, & Teague, 2001). At the same time, morning rush-hour traffic volumes decreased by more than 23 percent and peak ozone amounts decreased by 28 percent during the 17 days of the Olympics (Friedman et al., 2001).

Safe Routes to School programs help to reduce auto emissions near schools by encouraging walking and bicycling to school (EPA, 2003). A report by the U.S. Environmental Protection Agency using data from schools in Florida to compare travel choices and air quality implications revealed that school location and the quality of the built environment between home and school affect how children get to school. The study concluded that schools located closer to students' homes in walkable neighborhoods would reduce traffic, producing a 13 percent increase in walking and biking and a reduction of at least 15 percent in motor vehicle emissions (EPA, 2003).

Next: SRTS programs are part of the solution