Body size and health in children

Obesity is a medical term used to describe excess body weight that can affect your health. Children with obesity are at greater risk of health problems now and in the future. Following healthy eating and activity guidelines means you can help your child to grow into a healthy weight.

Key points

  1. 1 in 9 children in New Zealand have obesity, and a further 2 are overweight. These rates are higher among Māori and Pasifika children.
  2. Obesity can affect your child’s health, education and quality of life. Childhood obesity is associated with obstructive sleep apnoea, musculoskeletal problems, asthma and psychological problems, including body dissatisfaction, poor self-esteem and depression.
  3. Children with obesity are also more likely to have obesity as adults, and are therefore more at risk of developing long-term conditions such as type 2 diabetes, heart disease, dementia, some cancers, mental illness and chronic pain.
  4. The best thing you can do to support healthy growth for your child is to make changes to your family's lifestyle. This includes having daily physical activity, following healthy eating guidelines, making sure your child has enough sleep regularly and limiting screen time.
  5. Your child is much more likely to succeed in managing their weight if the whole family has a healthy lifestyle.


What are the causes of childhood obesity?

Excess weight or obesity is the result of an energy imbalance. This means too much energy (kilojoules/calories) in the form of food is put into your body and not enough energy is used up through exercise and being active generally. The excess energy is stored by your body as fat.

This is not always as simple as it sounds. We are often surrounded by less healthy food choices when we are out and about, and portion sizes can be very large. Healthy food can be costly and can take time to buy and prepare. Physical activity can also cost money and take up time that can be short for some parents.

Learning about simple, cheap and healthy ways to feed your family, and finding free and easy-to-access ways to be active can help you manage your time, your budget and your child's health. 

How is childhood obesity diagnosed?

Your doctor or other healthcare worker calculates your child's body mass index (BMI) and uses the recommended age- and sex-specific growth charts to work out if your child is in the healthy weight range for their height and age. BMI is calculated by dividing weight in kilograms by height in metres squared (kg/m²). The BMI result must be interpreted by a health professional as BMI can be affected by gender, age and muscle mass. You can find out if your child is in the healthy weight range for their height using this BMI calculator.

How can I prevent my child from developing obesity?

Pregnant women and new mothers can reduce their child’s risk of developing obesity by keeping themselves well during pregnancy (including eating well, being active and being within guidelines for gestational weight gain). This will reduce the mother's risk of developing gestational diabetes. Breastfeeding, where possible, can also protect against children developing obesity. Support from the rest of the family will help mothers to achieve these goals.

Make sure your child gets the recommended amount of sleep for their age. Children who sleep less than recommended are twice as likely to become overweight or develop obesity.

Follow the food and nutrition guidelines for eating and activity to support healthy growth for your child. Eating healthy food and being active every day makes a big difference to your child’s wellbeing.

Find out more about healthy eating for your children, healthy eating during pregnancysleep tips for children and active children.

Tips for 0 to 2-year-olds

  • Breast milk is best, if possible. If you are not breastfeeding, use an infant formula until your baby is 12 months old.
  • Healthy habits begin early, and you can encourage children to like fresh plain foods.
  • Don’t add salt, sugar, honey, sweeteners, soy sauce, cream, butter or margarine to your baby’s food.
  • For toddlers, offer water instead of sweet drinks and don’t add sugar or honey to fruit or cereals.
  • If your toddler doesn’t like vegetables, keep trying to introduce a variety of vegetables over time. Try offering raw, grated vegetables or pieces of soft fruit as an alternative.
  • Wholemeal bread instead of white bread is a healthy bread choice for toddlers. Bread with whole grains is better for older toddlers who can chew and grind their food well.

Tips for 2 to 12-year-olds

  • Provide three healthy meals every day, including breakfast.
  • Make children’s serving sizes smaller than an adult’s.
  • Offer healthy snacks (low in fat, salt and sugar) between meals, but don’t encourage continuous eating or grazing.
  • Take your children food shopping and encourage them to choose healthy foods, such as fruit and vegetables.
  • Make preparing food fun – involve children from an early age and let them do more as they get older.
  • Keep takeaways for occasional meals only (less than once a week), not as everyday foods.
  • Limit fruit juice and dried fruit – they contain a lot of sugar.
  • Make physical activity fun by finding lots of different ways for kids to play – running, jumping, skipping, riding a bike, bouncing on a trampoline, swimming, playing tag or backyard cricket.
  • Limit all screen time to 1 hour for 2 to 4-year-olds, and 2 hours for 5-year-olds.
  • Be a positive role model by making healthy food and activity choices yourself.

Tips for 13 to 18-year-olds

  • Eat a variety of foods from these four food groups every day: vegetables and fruit; breads and cereals; milk and milk products; lean meats, chicken, seafood, eggs, legumes (beans and pulses), nuts and seeds.
  • Always take time to eat a healthy breakfast so you have energy to start your day.
  • If you’re going to be out and about, take healthy snacks that are low in salt, sugar and saturated fat with you.
  • Many takeaways are high in fat, sugar and salt and should be kept for special occasions, not eaten every day.
  • Keep some fruit and a bottle of water in your bag.

See Resources for lots more ideas on how to develop healthy eating and activity habits with your whānau or family.

What can I do if my child has obesity?

Your doctor is available to discuss some ideas about different lifestyle habits for your child and your family as well as suggest support services that could help you.

As a parent, you can help your child a lot by:

  • being a role model for healthy living
  • involving the whole family in making lifestyle changes
  • following the healthy lifestyle tips listed above
  • helping your child learn about how to make healthy choices
  • making sure your child has regular sleep times.

Ask your doctor if there are local Māori health providers, Whānau Ora providers, Pacific Health providers or other community based organisations that can support you to help your child. Check out the  Resources for more ideas and support.

Learn more

The following links provide further information about childhood obesity.

My family food Health Promotion Agency, NZ
My family activities Health Promotion Agency, NZ


  1. Obesity statistics Ministry of Health, NZ, 2017
  2. Children and young people living well and staying well – childhood obesity programme baseline report 2016–17 Ministry of Health, NZ, 2017
  3. Food and nutrition guidelines for healthy children and young people Ministry of Health, NZ, 2015

Reviewed by

Vicky Campbell works as a liaison dietitian for the Auckland District Health Board. She has an interest in public health nutrition.
Julie Carter works as a liaison dietitian for the Auckland District Health Board. She has an interest in public health nutrition.
Daisy Power works as a liaison dietitian for the Auckland District Health Board. She has an interest in public health nutrition.
Credits: Health Navigator Editorial Team. Reviewed By: Auckland DHB community liaison dietitians Daisy Power, Julie Carter and Vicky Campbell Last reviewed: 26 Feb 2018