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Obesity in children


Expert reviewer, Dr Nagi Giumma Barakat, Consultant Paediatrician/Neurology
Next review due September 2022

Obesity in children is when children are very overweight and have too much fat in their body. Children need a healthy, balanced diet that gives them enough energy to grow and develop. But if they regularly take in more energy (calories) than they need and don’t do enough physical exercise, they’ll put on too much weight. Childhood obesity can lead to serious health problems such as diabetes, heart problems and cancer in later life.

Child's hand reaching for sweets in a bowl

Is my child obese?

Children are all different shapes and sizes. Boys are different from girls and your child will grow and develop at their own pace. This constant change and variation can make it hard to know if your child is a healthy weight. But your child may be at risk of being overweight if you notice they:

  • regularly eat the same size food portions as yourself or an older sibling or ask for more food during meals
  • wear clothes made for older children because they fit better
  • struggle to keep up with their friends when playing or at school during physical education (PE) lessons

If you’re concerned about your child’s weight or think they could be at risk of being overweight, take them to your GP surgery. Your child may be completely healthy but if you are in doubt, it is best to check.

How the GP works out if your child is a healthy weight

Your GP or health visitor will use a healthy weight calculation to work out your child’s weight compared to other children their age.

In adults, body mass index (BMI) based on height and weight is used. BMI values fall within specific ranges which indicate whether you’re overweight, underweight or a healthy weight. It’s much more difficult to calculate healthy weight in children because they’re still growing, and their height, weight and body fat changes a lot. So different measures are used. Specialists collect data on weight, height and age for a large number of children and use the figures to develop special charts called BMI centile charts. These show if your child is underweight or overweight for their age by comparing their BMI with the BMIs of other children of the same age and gender.

The charts are available at the Royal College of Paediatrics and Child Health if you wish to assess your child’s weight – see Other helpful websites.

  • If your child’s BMI is in the top 9% of BMIs collected for children their own age and gender, they’re classified as overweight.
  • If your child’s BMI is in the top 2% of BMIs collected for children their own age and gender, they’re classified as obese.

  • Your GP or health visitor will use these charts to assess your child. They will also check for other health conditions related to being overweight or obese. They might measure your child’s waist too. If they think there’s an issue with your child’s weight, they’ll ask about their diet and how active they are. They may also ask about any problems that may be caused by their weight, such as physical difficulties, teasing or bullying.

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Lifestyle changes

The best way to tackle obesity in children (and adults) is to make lifestyle changes. If your child is seriously overweight or obese, they’re taking in more calories than they’re using up. You’ll need to make changes to their daily routine – the foods they eat and the amount of activity they do. Think about changes you can make as a family to adopt healthier eating habits and become more active. Working together with your child or as a family is likely to be more successful long term because it will help you all make permanent changes to your lifestyle.

It’s also important for you to be a good role model. Children are very good at copying adults and if they see you eating well and exercising more, they’re more likely to join in.

To encourage your children, try setting goals and giving rewards and praise when they meet them. Choose smaller goals to start with, so that they can achieve them reasonably easily and are encouraged to carry on. And don’t make rewards food-based.

Food and drink

Your doctor may ask you to keep a diary of what your family eats and drinks. This can help you to see exactly what your child is eating and where you can make changes. Don’t forget to include snacks.

Children can sometimes be fussy eaters and it can be a challenge to get them to try new things. This is understandably a worry for parents, who know they need a balanced diet to help them grow and stay healthy. Encourage your child to choose a variety of foods from an early age. This will help them to get all the vitamins, minerals and nutrients they need. It is also helpful to make meals a social occasion and eat together as a family.

For ideas on what changes to make to improve your family’s diet, see our topic on Healthy eating. You can also get tips and advice in our wellbeing articles on Making mealtimes magical for kids, Sugar swaps for kids and Eight easy ways to get more veggies into your diet. You could encourage your child to help you write shopping lists so you can choose healthier options together.

Physical activity

Lots of children spend their time using computers or watching television and playing video games, rather than exercising. Try to limit these activities to under two hours a day.

Children under five should be encouraged to participate in a variety of physical activities for at least 180 minutes per day, at any intensity, including active and outdoor play.

Children over five need do at least 60 minutes a day of moderate to physical activity. This can be all in one go or over a number of sessions of 10 minutes or more. Again, it will help to get the whole family involved. For tips on how to help your child get active, see our wellbeing article on Fun ways to be active with your kids.

Exercise can bring many health benefits to your child and getting children active from an early age can instil healthy habits that may last a lifetime. Physical exercise can help make sure your child gets enough sleep too. A lack of sleep may contribute further to obesity (see our section on causes).

Will my child be referred to a specialist?

Making changes to your child’s lifestyle is the most important way to combat obesity. Your GP may refer your child to see a paediatric dietitian, a health professional who specialises in child nutrition and diet. They’ll come up with a plan that's tailored to your child based on their age and BMI centile. Losing weight isn’t always a good thing in children because they’re still growing. Your dietitian may even suggest that you aim to keep your child’s weight the same. As your child grows taller and their weight stays the same, their BMI centile will improve.

The GP may suggest that you and your child join a local programme to help them reduce weight and increase their exercise. These programmes can also help you to learn more about diet and nutrition, and to support and motivate your child.

Your GP may refer your child to see a paediatrician (a doctor who specialises in child health) if there may be a medical condition that’s causing your child’s weight problems. Or if they have a condition that’s causing or made worse by their weight.

Can my child have medicines?

Medicines for weight loss aren’t recommended for children under 12. There’s a medicine called orlistat that may help children who are 12 and over to lose weight. It works by stopping fat from the diet being absorbed from the gut. But it’s used very rarely and can only be prescribed in a specialist clinic. Your doctor will only prescribe orlistat if your child is very obese and has other health problems caused by their weight.

Can my child have surgery?

Weight-loss surgery for children is very rarely done and never for younger children. Your child’s doctor will only suggest it if you’ve tried everything else and nothing has worked. To be considered for surgery, your child will need to:

  • have been through puberty
  • be very obese
  • have other health problems related to their excess weight

Your doctor will discuss your child’s treatment choices with you.

What causes obesity in children?

There are a number of different things that can cause obesity in children:

  • eating a poor diet with large amounts of carbohydrates and high-fat and sugary foods, or portion sizes that are too large
  • inactivity – for example, not doing enough exercise and spending too much time watching television, playing video games or using a computer – and if children eat or drink while doing these screen-based activities, they consume more calories
  • lack of sleep, which can alter hormone levels and increase appetite
  • genetic (inherited) conditions, mental health problems, and some hormonal problems, which can lead to poor eating habits – see our FAQ: Can childhood obesity be caused by a medical condition?

Your lifestyle when you’re pregnant and in early motherhood may also affect your child’s weight. For example, a poor diet in pregnancy is linked to obesity in later life, while breastfeeding may lower your child’s risk of obesity.

If you’re obese, your children are also more likely to be obese. This may happen because you share the same eating or activity habits, or a combination of both. For more information, see our FAQ: Does my lifestyle impact on my child’s weight?

What complications could my child get?

If your child is overweight or obese, they are more likely to develop serious health problems in the future. Your child may be at risk of osteoarthritis, asthma, heart disease and stroke and some cancers, including bowel, breast, womb and prostate cancer.

Sometimes, being obese harms children during childhood. For example, if your child has flat feet, obesity can make walking more painful. Your child might also be affected by:


Obesity can also affect your child’s emotional and mental health. Your child may have low confidence or self-esteem, which may lead to depression.

Frequently asked questions

  • There are some medical conditions that can cause obesity in children but these aren't very common. They include:

    • genetic conditions such as Prader–Willi, Cohen and Bardet–Biedl syndromes
    • hormonal conditions such as Cushing's syndrome and hypothyroidism
    • mental health problems such as depression, which can lead to poor eating habits

    If your child does have an underlying medical condition, they’ll usually have other symptoms as well as being overweight.

    Most children become overweight or obese because they take in more energy (calories) than they need or aren’t active enough.

  • There’s evidence that suggests your health and choices you make when you’re pregnant, when your baby is born, and during their childhood, may affect your child’s weight.

    It’s very important to look after yourself when you’re having a baby. A poor diet when you’re pregnant is associated with an increase in your child’s risk of being severely overweight (obese) later in life. Being overweight when you’re pregnant and gaining a lot of weight during pregnancy are both linked to children being overweight and becoming obese in adulthood. Being overweight also increases your risk of developing diabetes while you’re pregnant (gestational diabetes). This can also lead to your child becoming overweight or obese in later life.

    Breastfeeding your baby can help to reduce the risk of them becoming overweight as they grow up. Breastfeeding has a number of health benefits for you and your baby, but it is not always an option for every new mum. Talk to your midwife or health visitor if you're having any problems.

    The most important way that you can influence your child’s health is by being a good role model. A child who has parents who are obese is more likely to be obese themselves. Eating a healthy diet and being active will encourage your child to do the same.

    For more information on encouraging good diet and exercise habits in your children, see our section on Lifestyle changes.

  • The UK has one of the highest rates of childhood obesity in Europe. In 2018, around one in 10 children aged four to five were classified as obese, and around one in five children aged 10 to 11 were.

    Worldwide, over 41 million children under five were overweight or obese in 2016 and over 340 million children aged five to 19 were. If the current trends continue, the number of overweight or obese young children will increase to 70 million by 2025.



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Related information

Tools and calculators

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  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, September 2019
    Expert reviewer, Dr Nagi Giumma Barakat, Consultant Paediatrician/Neurology
    Next review due September 2022

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