Overweight and obesity in children and adolescents: from early risk to lifelong impact

The numbers that define the problem

In the last few years, global data on childhood weight have shifted from worrying to historic. The World Health Organization (WHO) estimates that in 2024 about 35 million children under the age of five were overweight.(World Health Organization) For school age children and adolescents the figures are even more striking. In 2022 more than 390 million young people aged 5 to 19 were overweight, including about 160 million who were living with obesity

These are not only large absolute numbers. They represent a rapid change in how children grow up. WHO reports that the share of children and adolescents aged 5 to 19 who are overweight or obese has risen from about 8 percent in 1990 to about 20 percent in 2022. In other words, roughly one in five children in this age group is now above a healthy weight. UNICEF’s 2025 Child Nutrition Report goes further and notes that, for the first time, obesity among 5 to 19 year olds has slightly surpassed underweight as a form of malnutrition at the global level.

Taken together, these figures match the picture in your prompt. Around 35 million children under five and well over 390 million children and adolescents aged 5 to 19 are now overweight or obese. The problem is no longer confined to a small group of countries or to wealthy settings. WHO and UNICEF both highlight steady increases in low and middle income countries, particularly in urban areas.

How early obesity shapes a lifetime of health

The phrase “early obesity increases lifelong disease risk” is not just a slogan. WHO’s own questions and answers on childhood overweight and obesity state clearly that overweight and obese children are more likely to remain obese as adults and more likely to develop noncommunicable diseases such as diabetes and cardiovascular disease at a younger age. Childhood obesity is described as being associated with a higher chance of premature death and disability in adulthood, with risks influenced by both the age at which obesity begins and how long it persists.

Research summarized in recent reviews adds more detail. High body mass index (BMI) in adolescence is linked to increased risk of type 2 diabetes, high blood pressure, some cancers and musculoskeletal problems later in life. These complications do not wait until old age. Many appear in early or middle adulthood, compressing healthy life years and raising health care needs just as people reach their most economically productive years. From a public health and economic perspective, weight gained early in life can therefore be seen as a long running exposure that shapes disease patterns over decades.

This is why global agencies now talk about childhood obesity as one of the most serious public health challenges of the twenty first century. Early weight problems are not only about a higher number on the scale in childhood. They represent a shift in the trajectory of health, with consequences that accumulate as children become adults, parents and eventually older people who may pass both biological and environmental risks on to the next generation.

Environments that promote overweight and obesity

On a biological level, overweight and obesity arise when energy intake from food is persistently higher than energy expenditure through growth, basal metabolism and physical activity. WHO frames this simply as an imbalance between diet and physical activity. Yet global evidence makes it clear that this imbalance is rarely the result of purely individual choices in isolation. Children live in what researchers and policymakers often describe as “obesogenic environments” environments that promote consumption of high energy foods and discourage movement.

The 2025 UNICEF report “Feeding Profit” examines these environments in detail. It describes how many children and adolescents are constantly exposed to cheap, heavily marketed ultra processed foods and sugary drinks, while nutritious options such as vegetables, fruits and minimally processed staples are harder to find or more expensive. Advertising through television, social media and in and around schools directs children’s attention to snacks, fast food and sweetened beverages. These products are engineered for taste and convenience and they fit easily into busy family schedules. Over time they displace more traditional and typically more nutritious diets in both urban and rural settings.

At the same time, many children have fewer opportunities or incentives to move. Reports from WHO and national public health agencies highlight increased screen time, limited safe spaces for outdoor play, long school days with little physical education and urban designs that favour motorised transport over walking or cycling. For adolescents from less affluent families, WHO Europe has documented higher risks of obesity, physical inactivity and poor diet, showing how socioeconomic inequality and unhealthy environments reinforce each other.

Promoting movement and balanced diets as a public health investment

Against this backdrop, your statement that promoting movement and balanced diets during childhood is a critical investment in future public health is strongly supported by international evidence. WHO notes that overweight and obesity, and many of the associated diseases, are largely preventable. Prevention of childhood obesity is explicitly described as needing high priority.

Prevention does not mean asking individual children to shoulder the responsibility alone. Instead, it means creating conditions in which healthy eating and regular movement are the easier default choices. UNICEF and WHO both emphasize policy approaches that improve children’s food environments, for example by regulating marketing of unhealthy foods to children, improving school meals, making water and nutritious foods easily available and affordable and supporting families through social protection measures so that healthy diets are not a luxury.

Physical activity is the other pillar of this investment. Although specific recommendations for minutes per day vary by age, expert guidance consistently underlines that regular moderate to vigorous activity in childhood improves cardiovascular fitness, supports healthy growth of bones and muscles and reduces the risk of excessive weight gain. Creating safe spaces to play, integrating active transport to school, maintaining or expanding quality physical education and designing neighborhoods that invite walking and cycling all contribute to this goal. These actions are most effective when they reach children early and consistently, since habits formed in childhood often persist into adolescence and adulthood.

From current data to future trajectories

Recent modelling suggests that, if current trends continue, the number of children and adolescents living with obesity could keep rising sharply over the coming decades. An analysis in The Lancet has projected that by 2050 around 360 million young people aged 5 to 24 years may be living with obesity in the absence of strong preventive measures. At the same time, UNICEF estimates that about 188 million school age children and adolescents are already obese today and warns that global economic costs linked to childhood obesity could reach trillions of dollars annually in the near future.

These projections are not destiny, but they are a clear signal. When tens of millions of children under five already have overweight and hundreds of millions of older children and adolescents are above a healthy weight, the world is effectively writing future patterns of diabetes, cardiovascular disease and other chronic conditions into the lives of a large share of the next adult generation.

Seeing prevention as an investment means recognizing that each improvement in early life environments can shift that trajectory. Policies that protect children from aggressive marketing of ultra processed foods, that ensure access to balanced diets and that expand opportunities for enjoyable movement do not simply lower BMI curves in the short term. They also increase the probability that today’s children reach adulthood with healthier bodies and a lower burden of chronic disease. In that sense, the global figures on childhood overweight and obesity are not just statistics about the present. They are a preview of the health and economic landscape that societies will face in the middle of this century, and a reminder that acting early on movement and diet is one of the most powerful tools available to change that future.