Childhood obesity has been called “one of the most serious public health challenges of the 21st century,” and with good reason.

Obesity can harm nearly every system in a child’s body-heart and lungs, muscles and bones, kidneys and digestive tract, as well as the hormones that control blood sugar and puberty-and can also take a heavy social and emotional toll. What’s worse, youth who are overweight or obese have substantially higher odds of remaining overweight or obese into adulthood, increasing their risk of disease and disability later in life.

Globally, an estimated 43 million preschool children (under age 5) were overweight or obese in 2010, a 60% increase since 1990. The problem affects countries rich and poor, and by sheer numbers, places the greatest burden on the poorest. Of the world’s 43 million overweight and obese preschoolers, 35 million live in developing countries. By 2020, if the current epidemic continues unabated, 9% of all preschoolers will be overweight or obese-nearly 60 million children.

Obesity rates are higher in adults than in children. But in relative terms, the U.S., Brazil, China, and other countries have seen the problem escalate more rapidly in children than in adults.

Over the past three decades, childhood obesity rates have tripled in the U.S., and today, the country has some of the highest obesity rates in the world: one out of six children is obese, and one out of three children is overweight or obese. Though the overall U.S. child obesity rate has held steady since 2008, some groups have continued to see increases, and some groups have higher rates of obesity than others.

The causes of obesity in children

The problem of childhood obesity in the United States has grown considerably in recent years. Approximately 14.7 million, or 19.7%, of children and adolescents are obese. Obesity is a complex medical condition and is difficult to treat. Overweight children are much more likely to become overweight adults, and obesity can lead to diabetes, heart disease, and other health challenges. Given these challenges everyone, including doctors and families, wants to find ways to better help children and adolescents who live with obesity.

Obesity is currently defined by someone’s height and weight. If a child’s Body Mass Index (BMI; a number calculated from height and weight) is more than 95th percentile for their age, then that is defined as obesity. Obesity most commonly begins between the ages of 5 and 6, or during adolescence. Studies have shown that a child who is obese between the ages of 10 and 13 has an 80% chance of becoming an obese adult.

The causes of obesity are complex and include genetic, biological, behavioral and cultural factors. Obesity occurs when a person eats more calories than the body burns. If one parent is obese, there is a 50% chance that his or her child will also be obese. However, when both parents are obese, their children have an 80% chance of being obese. Although certain medical disorders can cause obesity, less than 1% of all obesity is caused by physical problems. Obesity in childhood and adolescence can be related to: 

• Eating habits
• Lack of physical activity or exercise (i.e., couch potato kids)
• Genetics or family history of obesity
• Not enough sleep
• Living conditions (like not having healthy food options, not having a place to play actively) 
• Medical illnesses (endocrine, neurological problems) 
• Medications (steroids, some psychiatric medications) 
• Stressful life events or changes (separations, divorce, moves, deaths, abuse) 
• Family and peer problems 
• Low self-esteem 
• Depression or other emotional problems 

There are many risks and complications with obesity. Physical consequences include:

• Increased risk of heart disease 
• High blood pressure 
• Diabetes 
• Breathing problems 
• Trouble sleeping 
• Joint pain 
• Hormonal changes 

Child and adolescent obesity is also associated with an increased risk of emotional problems. Teens with weight problems tend to have much lower self-esteem. Depression, anxiety, and obsessive compulsive disorder can also occur. 

Why is obesity spreading in the U.S.?

In the 1970s, 5% of U.S. children ages 2 to 19 were obese, according to the CDC’s current definition; by 2008, nearly 17% of children were obese, a percentage that held steady through 2010. Obesity is more common in boys than girls (19% versus 15%). Obesity rates in boys increased significantly between 1999 and 2010, especially among non-Hispanic black boys; but obesity rates in girls of all ages and ethnic groups have stayed largely the same.

Hispanic (21%) and non-Hispanic black (24%) youth have higher rates of obesity than non-Hispanic white youth (14%), a continuing trend. Nearly 10% of U.S. infants had a high “weight for recumbent length”-a measure that’s similar to the body mass index but used in children from birth to age 2. From 1999 to 2010, Mexican American infants were 67% more likely to have a high weight for recumbent length than non-Hispanic white infants.

Even among the youngest of children, it’s clear that obesity rates are rising across the globe. Equally clear is that it’s very, very hard for anyone who becomes overweight to lose weight, at any age. Preventing obesity in a child’s earliest years (and even before birth, by healthy habits during pregnancy) confers a lifetime of health benefits. And it’s the most promising path for turning around the global epidemic.

Despite growing recognition of the problem, the obesity epidemic continues in the U.S., and obesity rates are increasing around the world. The latest estimates are that approximately 34% of adults and 15–20% of children and adolescents in the U.S. are obese. Obesity affects every segment of the U.S. population. Obesity increases the risk of many chronic diseases in children and adults. The epidemic of obesity arose gradually over time, apparently from a small, consistent degree of positive energy balance. Substantial public health efforts are being directed toward addressing obesity, but there is not yet clear evidence of success. Because of the complexity of obesity, it is likely to be one of the most difficult public health issues our society has faced.

Are there ways to fight obesity?

Children who take in too many calories and don’t get enough exercise or sleep are at risk for obesity. Some children may have only limited access to healthy foods like fruits and vegetables. This includes those in lower-income neighborhoods. Many children don’t get enough physical activity. This is because more children are watching TV, playing video games, or doing other screen-time activities. To help combat these factors, parents can make these positive changes in kids’ lives:

• Move more as a family. Children ages 3 through 5 should be physically active throughout the day. This includes active play like tricycle riding and skipping. Children ages 6 through 17 need at least 60 minutes of medium- to high-intensity physical activity every day. This can include fun aerobic activities like playing tag and jumping rope. Set a positive example for your children by being active yourself. Make exercise a part of your daily routine. Try taking a family walk, dancing, biking, or playing an outdoor game together as often as you can.
• Set regular sleep routines. Good sleep helps prevent diseases. These include type 2 diabetes and obesity, injuries and problems with attention and behavior. Children who don’t get enough sleep are at risk for unhealthy weight gain. Remove screens from your child’s room. Stop use of screens at least 1 hour before bedtime. Follow a consistent sleep schedule, even on the weekends. This can help children sleep better.
• Model a healthy eating plan. Following a healthier diet as a family can help children reach and stay at a healthy weight. Healthy and nutritious foods include a variety of vegetables and fruits, whole grains, lean protein foods, and low-fat and fat-free dairy products. Keep soda and chips out of the house. Or have them only on very special occasions. Try serving your children kid-friendly snacks. These include fruit smoothies, raw veggies with yogurt dip, and celery with peanut butter. If fresh produce isn’t available or costs too much, look for frozen choices.
• Watch portion sizes. Over the last few decades, portions of foods in both grocery stores and restaurants have ballooned. Make sure the amount of food your children eat stays within the USDA advice for meal sizes for each food group.
• Limit screen time. Too much screen time can lead to poor sleep, weight gain, lower grades in school, and poor mental health in children. The American Academy of Pediatrics recommends creating a family media plan to help your family set media priorities. In this plan health, academic and social goals are met first.
• Focus on health, not body appearance. Blame and guilt about a body shape or size is not helpful. It is often harmful and can affect the success of treatment. Similar to other chronic diseases such as asthma, obesity treatment should focus on overall health and quality of life.

Is the food industry to blame?

Eating highly processed foods, saturated fats and added sugar on a regular basis is linked to many negative health effects. Fast food is one of the major culprits of the global obesity epidemic. Research also shows that, in the long run, a poor diet that is high in junk food can also lead to cardiovascular disease, type 2 diabetes, some types of cancer and even earlier mortality rates.

Food manufacturers didn’t start off trying to make people fat and sick. They just wanted to sell more food; that’s their job. But as they got better at it, it became clear that weight gain was a byproduct of that business model. Now, the people who run those companies are caught between their fiduciary responsibility to maximize shareholder value and their social responsibility to not contribute to a large and growing public health problem.

When obesity as a global health issue first came on the radar, the food industry sat up and took notice. But not exactly in the way you might imagine. Some of the world’s food giants opted to do something both extraordinary and stunningly obvious: they decided to make money from obesity, by buying into the diet industry.

Weight Watchers, created by New York housewife Jean Nidetch in the early 1960s, was bought by Heinz in 1978, who in turn sold the company in 1999 to investment firm Artal for $735m. The next in line was Slimfast, a liquid meal replacement invented by chemist and entrepreneur Danny Abraham, which was bought in 2000 by Unilever, which also owns the Ben & Jerry brand and Wall’s sausages. The US diet phenomenon Jenny Craig was bought by Swiss multinational Nestlé, which also sells chocolate and ice-cream. In 2011, Nestlé was listed in Fortune’s Global 500 as the world’s most profitable company.

What we choose to eat plays a large role in determining our risk of gaining too much weight. But our choices are shaped by the complex world in which we live-by the kinds of food our parents make available at home, by how far we live from the nearest supermarket or fast food restaurant, even by the ways that governments support farmers. In the U.S. and many parts of the world, the so-called food environment-the physical and social surroundings that influence what we eat-makes it far too hard to choose healthy foods, and all too easy to choose unhealthy foods. Some even call this food environment “toxic” because of the way it corrodes healthy lifestyles and promotes obesity.

Americans get new solutions to obesity every day — a new pill, a new superfood, surgery — but people keep getting bigger. In 1990, less than 15% of the U.S. population was obese. Today, about one fifth of children and adolescents and one third of adults are obese. This alarming rise of obesity has been paralleled by an increase in diet fads and fitness crazes, all marketed with the message “eat less and exercise more” — the obesity epidemic’s destructive motto. Yet, American culture blames the obese person, viewing them as lacking the willpower to change their overindulging habits. The food industry is at the heart of this problem. Companies constantly victimize themselves within the issue and blame the individual.

The obesity epidemic has taken an especially large toll on children and adolescents — those who were born into the age of processed, sugary foods. The toll has been as much psychological as physical. A child’s self-esteem is greatly affected by their being fat. Moreover, it isn’t even their fault that they’re overweight. Companies shamelessly exploit the vulnerability of children with play spaces in fast food joints, cartoon characters on products, etc. Junk food has even infiltrated schools, where kids are supposed to be safe. School lunches have evolved over years of budget cuts to depend on easily reheatable, sugar, and grease filled food.

Private profit and political interests have been repeatedly put before public health. The food industry has changed the conversation from real food and cooking to reengineer processed food and exercise more. So many industries profit over people being unhealthy — it’s in their interest to have unhealthy people. As a society, Americans need to stop blaming the individual. The food industry needs to be demonized like the once rampant tobacco was. The government needs to stop putting the profits before public health.