Obesity and Overweight

What is meant by obesity and overweight? 

The terms obesity and overweight refer to weight ranges that are higher than what is generally considered healthy. 

Obesity is a chronic health condition. In Wales, more people  are living at a higher weight, and  because of this it’s becoming harder for society to understand what a healthy weight range looks like. 

For adults over 18 the usual way to estimate whether someone is a healthy weight is by using Body Mass Index (BMI). This is calculated by dividing weight in kilograms by height in meters squared. While BMI doesn’t measure body fat directly, it is widely used to show weight in relation to height.  

Tools are available to calculate BMI, and these will take family background into account. This is important because people from an Asian, Black African, African-Caribbean or Middle Eastern background can have a higher risk of health problems at a lower BMI (Calculate your body mass index (BMI) – NHS). 

 BMI categories for adults over 18 are: 

• underweight <18.5 
• healthy weight 18.5 to <25 
• overweight 25 to <30 
• obese 30 to <40 
• morbidly obese 40+ 

BMI is calculated differently for children and in Wales health professionals work out if children are living with overweight or obesity as part of the Child Measurement Programme in schools.

Limitations of BMI 

BMI measures weight in relation to height but can’t distinguish between fat, muscle, or bone mass. This means a very muscular person, such as an athlete, could be classified as “overweight”. Other methods, such as height to weight ratio, can help show much fat is stored around the waist. Carrying excess fat around the waist can increase the risk of health issues such as heart disease and type 2 diabetes. To stay in the healthy range,  your waist measurement should be less than half your height: Calculate your waist to height ratio – NHS.

Why is obesity and overweight a problem in Wales? 

Living with overweight or obesity increases the risk of a wide range of chronic diseases. This includes type 2 diabetes, hypertension, and cardiovascular disease such as heart attack and stroke. It can also increase the risk of some types of cancer, kidney disease, obstructive sleep apnoea, gout, osteoarthritis, liver disease and other health conditions such as dementia. Obesity leads to an increased number of years lived with a disability and lowers life expectancy.

Learn more about the health risks of obesity.

Living with obesity can impair a person’s well-being, quality of life and ability to earn.  For some it may also impact mental health, leading to issues such as low self-esteem, poor self-image, and low confidence levels. 

Obesity is becoming more common in Wales, as it is around the world. The healthcare costs associated with treating obesity and the health conditions caused by it are high and continuing to increase. 

The direct costs to cover the treatment of people living with overweight or obesity and obesity related diseases in 2024 were estimated at £0.5 billion, and the indirect costs (such as loss of earnings due to obesity related illness and early death) were estimated to be £2 billion (Source: A summary of trends in risk factors for non-communicable diseases – Public Health Wales).

How many people in Wales are living with overweight or obesity? 

The proportion of children and adults in Wales who maintain  a healthy weight is declining: 

• In 2022, 62% of adults were living with either overweight or obesity, with a quarter of those living with obesity.
• In 2023-24 13.7% of children started school living with overweight and 11.8% with obesity. These pattern bein long before children reach school age, shaped by influences in pregnancy, infancy and early childhood.
• Wales has the highest levels of children living with obesity in the United Kingdom.
• Obesity rates are higher in the most disadvantaged communities.

What causes obesity and overweight?

Overweight and obesity are due to the interaction of individual factors such as physiological processes and food and activity patterns across life, and environmental factors that play a role in determining both nutrition and physical activity.

At its simplest, overweight or obesity is the result of an energy imbalance which happens when the energy we consume from food and drink is more than the energy we use through our daily activities. The extra calories are stored as body fat, and over time this leads to weight gain. 

However, there are many complex interconnected factors that lead to overweight and obesity. These can include:

• Individual factors such as genetics, underlying health conditions, the effects of certain medications, what we eat and drink, and how active we are.  
• Psychological factors including disrupted sleep, high stress levels, or emotional coping strategies involving food.
• Social and economic pressures, such as limited time, tight budgets, or demanding work and family responsibilities also affect the options people can realistically choose from. These pressures can make it harder to eat well or be active, even when people are motivated to do this.
• The environment that we live in plays a major role in influencing what food and drink are available, affordable and appealing, and how easy or difficult it is to be active.

How can we support people with healthy weight in Wales? 

We can help people stay healthy from birth, through childhood to adulthood by making changes to the world around them.

The longer people live with obesity and overweight the greater their chance of developing health problems and developing these at an earlier age.  However, weight loss reduces the risk of developing these diseases in a dose-related manner. This means that the more weight lost, and the closer to a healthy weight the individual becomes, the better the outcome. 

Obesity and overweight are driven by complex factors in our society, in our environment and by economic conditions which can influence and limit the choices available to individuals. This means that effective solutions must focus on improving the policy environment and supporting people at every stage of the life course, from conception and pregnancy, through childhood and adolescence and into young, mid and older  adulthood.  

The Welsh Government has launched Healthy Weight Healthy Wales as a long-term strategy to reduce the number of people living with overweight and obesity. 

Supporting families and the foundations of lifelong health

Actions taken in the first years of life will have the biggest long-term impact on health. The early years are a critical period for shaping lifelong dietary patterns and broader health behaviours. Maternal nutrition and healthy weight gain during pregnancy help to support a child’s healthy development and reduce their risk of obesity later in life. There is evidence that the following factors can also help children live with a healthy weight:  

• breastfeeding
• preventing rapid weight gain in infancy
• timely  introduction of solid foods at around 6 months
• physical activity
• a healthy balanced diet throughout infancy, childhood and adolescence

Ensuring families have the right support and environments during these critical stages helps to lay the foundations for healthy growth and a healthy weight throughout life.

Actions to create healthier food environments and support active lives 

We need to create supportive environments where healthier eating and regular physical activity are the easiest, most affordable options for everyone. Achieving this requires co-ordinated action across the whole system: from reformulating manufactured food and drinks and restricting the marketing of products high in fat, salt and sugar, particularly to children and  communities experiencing inequities, to reducing poverty and addressing  transport and urban planning. Everyone has a role to play in creating the conditions that make healthier choices easy, affordable and part of everyday life.

Built‑environment professionals can help ensure that new developments and regeneration projects prioritise access to green spaces, active travel routes , access to healthier food, better planning to manage hot food takeaways  and community facilities  that support healthier living.

Workplaces and schools also have a key role by offering healthier food and drink options and creating opportunities for physical activity before during and after the working day.

The food industry can contribute by reformulating products to reduce the amount of fat, sugar and salt people consume, and by ensuring that more affordable, nutritious options are available and accessible to all communities.

Changes can also be made in policy, regulation and practice. This includes making sure that food and drink provided in settings such as hospitals and schools is nutritious, and that young people have safe spaces to play and be active.

This includes work to make it easier for people in Wales to achieve a healthy weight being delivered through the Whole Systems Approach to Healthy Weight.

These system‑wide actions are part of the ambitions of Welsh Government’s Healthy Weight Healthy Wales Strategy and complements wider work across public health teams.

Helping individuals to be a healthy weight

Local support (pathway) services are accessed through health board weight management services. 

The standards for pathway services have been set out by Welsh Government under the Healthy People theme of the Healthy Weight Healthy Wales Strategy and PHW reviews how these services are delivered locally.

PHW has developed a website Healthy Weight Healthy You to support individuals to reach and maintain a healthy weight. (This aligns with Level 1 of the All-Wales Weight Management Pathway.) The website uses a unique ‘Find Your Journey’ tool, which was developed to focus on the challenges and motivators associated with achieving a healthy weight and offers support to allow people to make a sustained change.