Current Environment:

What is childhood obesity?

Obesity occurs when a child is significantly over the ideal weight for her height. Like adults, children become obese when they eat more calories than they use. Obesity in children is determined by using a body mass index (BMI) percentile. BMI is a measure of weight in relation to height.

Obesity can increase a child’s risk for serious and chronic medical problems, such as type 2 diabetes, high blood pressure (hypertension), high cholesterol, orthopedic problems, and liver disease.

Researchers continue to search for ways to treat obesity, but taking preventive measures has proven to be the best method so far. This means eating a healthy diet based on vegetables, fruits, legumes, whole grains, and lean protein. It is also important to maintain an active lifestyle by getting at least an hour of physical activity a day.

How common is childhood obesity?

The Centers for Disease Control and Prevention estimate that 19.7 percent of 2- to 19-year-old American children are obese, as measured by their body mass index (BMI) percentile. This means that childhood obesity affects about 14.7 million children and adolescents.

How is a child’s risk for obesity determined?

There are several tools your doctor might use to determine if your child is at risk for obesity, including:

  • plotting your child’s BMI percentile yearly to see if there's a sudden increase
  • identifying babies who gain weight too rapidly in infancy; studies show that these babies are at risk for becoming overweight as they get older
  • birth weight and gestational diabetes: these factors may increase a child’s risk for obesity and type 2 diabetes later in life
  • a family history of obesity, type 2 diabetes, hyperlipidemia, hypertension, sleep apnea, and early heart attack: these factors can also put a child at increased risk for obesity and associated medical complications

Childhood Obesity | Symptoms & Causes

What are the symptoms of childhood obesity?

Each child may experience different symptoms but some of the most common include:

  • appearance: stretch marks on hips and abdomen; dark, velvety skin (known as acanthosis nigricans) around the neck and in other areas; fatty tissue deposition in breast area (an especially troublesome issue for boys)
  • psychological: teasing and abuse; poor self-esteem; eating disorders
  • pulmonary: shortness of breath when physically active; sleep apnea
  • gastroenterological: constipation, gastroesophageal reflux
  • reproductive: early puberty and irregular menstrual cycles in girls; delayed puberty in boys; genitals may appear disproportionately small in males
  • orthopedic: flat feet; knock knees; dislocated hip

What are the causes of childhood obesity?

There are many reasons why a child may be obese, including medical or genetic ones. In most cases, though, children are overweight because they eat unhealthful foods and lead a sedentary lifestyle. If you think your child is overweight because of a medical condition, consult your pediatrician who can perform tests to check.

Reasons why more and more children are becoming obese include:

  • behavioral factors: eating bigger portions, eating foods that are calorie-rich but nutrient poor (junk foods), spending lots of time in front of the television or computer, and spending too little time doing physical activities
  • environmental factors: easy access to high-calorie junk foods, few opportunities for physical activity, lack of parks and playgrounds in some communities
  • genetic factors: A child is at increased risk for obesity when at least one parent is obese. However, genes do not necessarily mean a child is destined to be overweight — there are several steps a child can take to lower his risk.
  • medications: steroids, some antidepressants, and others
  • medical conditions: Genetic syndromes like Prader-Willi, and hormonal conditions like hypothyroidism are among the medical disorders that can cause obesity.

The “body weight set point theory” suggests that weight is determined by complex interactions of genetic, hormonal, and metabolic factors.

Childhood Obesity | Diagnosis & Treatments

How is obesity in children diagnosed?

To determine if a child is obese, a doctor will use the child's body mass index (BMI) to obtain a percentile ranking. BMI is a measure of weight in relation to height and it indicates the amount of body fat your child has.

BMI is a measure of weight in relation to height and indicates the amount of body fat your child has. If your child’s BMI falls at or above the 95th percentile, he is considered obese. In this case, your child’s doctor might do a full physical exam and screen for the following:

  • diabetes
  • high blood pressure
  • abnormal blood lipids (high cholesterol, high triglycerides, and low levels of good, HDL cholesterol)
  • fatty liver
  • menstrual problems in girls
  • psychological problems

Your child is considered overweight and at risk for obesity if his BMI falls between the 85th and 95th percentiles. In this case, your doctor might screen for the following:

  • family history of cardiovascular disease, elevated total cholesterol, diabetes, parental obesity
  • large increases in BMI assessments from year to year
  • person concerns about weight (emotional or psychological)
  • concerns related to weight and perception of self as overweight
  • blood pressure

How we treat childhood obesity

Whether your child has genes causing weight gain or he is obese simply from eating too much unhealthful food, lifestyle changes are key factors in long-term weight loss. This includes dietary improvements and increased physical activity.

But weight loss is not always the goal when treating excessive weight in childhood. In some cases, especially with young children, a child can “grow into” his weight by maintaining his weight as he grows taller. In older teenagers with a higher body mass index (BMI), weight loss might become a treatment goal, as the rate of growth slows.

Whatever the case, it's important that your child's goals are realistic. This might include a modest reduction in portion sizes, small but consistent improvements in the types of foods he eats, and adopting a more active lifestyle.

Depending on your child's needs, a multi-specialty team consisting of a physician, a registered dietitian, a mental health professional, and an exercise specialist may be helpful to develop a specific treatment plan that can include:

  • nutrition counseling and modification of diet quality and caloric content
  • increased physical activity
  • behavior modification to address self-esteem and attitudes about food
  • individual or group therapy focused on changing behaviors and confronting feelings related to weight and normal developmental issues
  • family counseling to help support changes in the home


The low-glycemic diet

Traditionally, overweight individuals have trouble following low-fat and low-calorie diets, and those who do lose weight typically have a difficult time keeping it off long-term. This is usually because they feel deprived by the limited amounts and types of foods they can eat.

The Optimal Wellness for Life (OWL) program uses an approach known as a low-glycemic diet. This diet:

  • combines slowly digested carbohydrates — like vegetables, fruits, beans, and minimally processed grains — with protein and healthy fats like nuts, avocado and olive oil, all of which help us stay full longer after eating
  • is based on whole foods that digest slowly, helping blood sugar and hormones stay at a steady level for many hours after eating

How do I follow a low-glycemic diet?

Following a low-glycemic diet is easier than it may sound. You don't have to memorize the glycemic index or count grams of carbohydrates in foods. Instead, you can:

  • eat fiber-rich, natural carbohydrates such as non-starchy vegetables, fruits, and beans along with protein and healthy fat (like nuts, avocado, or olive oil)
  • eat grain products in their least-processed state possible (for example, stone ground whole grain bread rather than white bread)
  • have a sugary treat, but do so only in moderation and after a balanced meal
  • limit fruit juice to 1 cup a day, avoid sugary soda, and drink mostly water

Research has shown that the low-glycemic diet has many benefits, including:

  • lowering risk for diabetes, heart disease, and fatty liver
  • lowering blood sugar and cholesterol levels in people with diabetes, both type 1 and type 2
  • controlling appetite, which supports healthy weight in both kids and adults

However, to be as healthy as possible, children should eat a healthy diet and obtain daily physical activity.

Physical activity

Eating right is half the equation for optimal weight and fitness. Regular physical activity is the other half.

What is the best form of physical activity for an obese child?

If your child hasn't been active in the past, start slowly. Intense physical activity and competitive sports may, at first, be intimidating and even dangerous for an obese child who is not physically fit. But just 20 minutes of daily walking can get things moving in the right direction for a child who has been previously sedentary.

It's also an important move toward long-term weight management. To keep your child active, focus on making physical activity fun but also appropriate to her developmental level and ability. This can raise her self-confidence and motivate her to continue.

Experts suggest at least 60 minutes of moderate physical activity daily for most children. Running, bicycling, jumping rope, dancing, and playing basketball or soccer are good ways for them to be active.

What are the long-term consequences of childhood obesity?

  • increased risk of being overweight or obese as an adult
  • increased risk for medical problems such as asthma, diabetes, heart disease, liver disease, reproductive problems, and some cancers
  • psychosocial disabilities, including social isolation, depression

How Boston Children’s Hospital approaches obesity

Boston Children’s has five hospital-based programs to help children and their families manage their weight.

  • Optimal Wellness for Life (OWL) Program: The largest pediatric weight management clinic in New England treats overweight children between 2 and 20.
  • The One Step Ahead program: Focused on prevention and management, OSA treats 3- to 13-year-olds who are part of the Boston Children’s Hospital Primary Care Center (CHPCC).
  • STEP: Based in the Adolescent and Young Adult Clinic at Boston Children’s, this multidisciplinary program works with 13- to 25-year-olds in their primary care clinic to develop a teen- and young adult-friendly approach to weight and lifestyle management.
  • Preventive Cardiology Clinic (Lipid Clinic): The preventive cardiology program serves patients who have elevated lipid levels and/or hypertension. Seventy percent of the children seen in this program are obese, and thus many of the interventions focus on the same types of lifestyle and behavior changes as the clinical obesity programs.
  • Adolescent Weight Loss (Bariatric) Surgery Program: This multi-disciplinary program for adolescents who are considering surgical interventions to reduce weight. Patients must have attempted at least six months of medically supervised weight loss before they would be considered for eventual surgery.

Preventing childhood obesity

Researchers continue to search for ways to treat obesity. At this point, prevention is the best way! This means eating a healthful diet based on vegetables, fruits, legumes, whole (instead of refined) grains, protein, and healthy fats. Also, maintain an active lifestyle by aiming to getting an hour of physical activity a day.

You can also help your child to maintain a healthy weight by:

  • protecting the home environment: stocking your home with only healthful foods so that your child is not tempted to snack on unhealthful ones
  • role modeling: parents who eat a healthful diet and maintain an active lifestyle will set a positive example for their child
  • serving water instead of sugar-sweetened drinks
  • offering age-appropriate portion sizes and keeping serving platters and bowls off the table to avoid overeating
  • limiting screen time to two hours a day (TV, computer, and video games)
  • not using food as a reward for good behavior, academic achievement, or eating a healthful food

If my child has been diagnosed with an obesity-related condition such as type 2 diabetes, is it too late to make changes that will help him?

It's never too late to improve health. Many problems such as high cholesterol and high blood pressure, elevated insulin, fatty liver, and even type 2 diabetes can be reversed. With careful monitoring of changes in height and weight, many weight-related problems can be identified early enough to prevent the progression to more serious and chronic health problems.

Our community partnerships

Boston Children's has initiated several community programs and partnerships to help further address overweight and obesity in local Boston communities:

  • Healthy in the City (FIC) program: Boston Children's works with 11 Boston community health centers to offer culturally sensitive obesity prevention and management programs. Boston Children's is working with the centers to track long-term results of diet and lifestyle changes.
  • Healthy Kids, Healthy Communities: a partnership between Boston Children's, the Boston Red Sox, and Northeastern University. This is an obesity prevention program targeting preschool-age children. The program partners with Action for Boston Community Development, Head Start, and the Boston Centers for Youth and Families to provide nutrition workshops and exercise programs for families in the community.
  • OWL on the Road is an obesity treatment program serving financially disadvantaged children in Boston. The program is provided through the OWL clinic and funded from a grant from the New Balance Foundation. Each week, a team consisting of a physician, nurse practitioner, dietitian, and psychologist visits neighborhood health centers to provide services free of charge.

Childhood Obesity | Coping & Support

Boston Children's offers three programs that provide medical, nutritional, and behavioral supports:

  • The Optimal Wellness for Life (OWL) Program treats overweight and obese children between 2 and 20.
  • The One Step Ahead program treats children between 3 and 13, with a focus on prevention.
  • STEP treats patients between 13 and 25 and focuses more on teens and young adults, although encourages family involvement as well.

All of these programs are family based to some extent; that is, they encourage an approach that includes all family members and not just the overweight child.

Childhood Obesity | Research & Clinical Trials

At Boston Children’s Hospital, our care is informed by our research, and we have many studies investigating causes and treatments of obesity. Read more about some of our research breakthroughs:

Sugary calories in liquid form

Our recent study published in the New England Journal of Medicine (NEJM) provides definitive evidence that drinking sugar-sweetened beverages directly impacts weight gain and pediatric obesity.

Boston Children’s researchers Cara Ebbeling, PhD, and David Ludwig, MD, PhD, find that compared to adolescents who consistently drink sugar-sweetened beverages, those who stopped drinking them for a year gained significantly less weight and avoided BMI increases.

Boost your metabolic rate

Recent research by Cara Ebbeling, PhD; David Ludwig, MD, PhD; and colleagues in the New Balance Foundation Obesity Prevention Center suggest that all calories are not alike from a metabolic perspective. Reducing consumption of highly processed carbohydrates — like white bread, white rice, refined breakfast cereals, and sugary beverages — can provide a metabolic boost of several hundred calories a day, equal to an hour of physical activity. This metabolic boost may be a key to successful long-term weight loss maintenance.

Reviving leptin's promise for obesity

The 1995 discovery of leptin, a hormone that suppresses appetite, raised hopes of an obesity cure. But researchers later discovered differences in the way the brains of obese people and their normal-weight peers respond to leptin. Specifically, they found that the brains of obese people become leptin-resistant.

Now, Umut Ozcan, MD, and colleagues in Boston Children’s Department of Endocrinology report two existing drugs can restore the brain's sensitivity to leptin in obese mice. How this translates into humans is far from certain, but researchers are beginning to try to answer this question through clinical trials.

Cracking the code on obesity

When an international consortium led by Joel Hirschhorn, MD, PhD, of Boston Children’s Divisions of Genetics and Endocrinology, analyzed data from about 90,000 people, they discovered six new genetic variants linked with body mass index. Most of the variants highlight genes active in the brain, suggesting that differences in appetite regulation may play a role in obesity. The team is now performing larger-scale studies in an attempt to identify additional genetic variants with the goal of one day developing an effective treatment for obesity.

Obesity risk factors more prevalent among black and Latino children

Certain groups, including blacks and Hispanics, are at great risk of obesity during childhood. But according to a study by Elsie Taveras, MD, MPH, director of Boston Children’s One Step Ahead (OSA) Program, clinicians can help to lower the risks in these groups by encouraging mothers to breast-feed longer, counseling parents to keep TVs out of children's bedrooms, and encouraging healthful eating and sleeping habits. Her study looked at black and Hispanic mother-child pairs from pregnancy through age 4.

A separate study comparing rates of obesity between Haitian-born children and U.S.-born Haitian children found that the risk of obesity rises with every year spent in the United States. The study underscores how environmental factors in America play a role in the rising rates of obesity among children.

Childhood Obesity | Programs & Services