Healthy Weight in Children: A Practical Guide for Parents

How Weight Is Assessed in Children

Unlike adults, where a single BMI threshold is used, weight in children is assessed using BMI-for-age percentiles, which account for the fact that a healthy BMI changes considerably as children grow. A child's BMI is plotted on a growth chart for their age and sex - a result between the 5th and 85th percentile is generally considered healthy, between the 85th and 95th percentile is classified as overweight, and above the 95th percentile as obese.

These categories give a useful signal, but they are not the full picture. Muscle mass, pubertal stage, and body proportions all affect the interpretation. A GP assessment includes growth history, not just a single data point - a child tracking consistently at the 90th percentile from infancy is very different from a child whose weight has crossed percentile lines over recent years.

Why It Matters Long Term

Excess weight in childhood matters for several reasons. In the immediate term, it is associated with lower energy levels, joint discomfort, sleep-disordered breathing, and in some children, psychosocial difficulties including bullying and low self-esteem. Over the longer term, children who carry excess weight are at higher risk of developing type 2 diabetes, high blood pressure, fatty liver disease, and cardiovascular disease earlier in life. There is also a strong tracking effect - children with obesity are more likely to carry excess weight into adulthood.

At the same time, it is worth noting that a child can have a weight in a higher percentile and still be metabolically healthy, particularly if they are active and eating well. The aim is always health, not a number on a scale.

What Drives Weight Gain in Children

The factors that contribute to excess weight in children are well understood and largely environmental:

• Diet quality - high intake of ultra-processed foods, sugary drinks, and energy-dense snacks, combined with low fruit, vegetable, and fibre intake
• Portion sizes - children's portion needs are much smaller than adults; offering adult-sized portions contributes to overeating
• Screen time - excessive screen use displaces physical activity and is independently associated with higher calorie intake due to distracted eating and exposure to food advertising
• Sleep - insufficient sleep disrupts hormones that regulate appetite, leading to increased hunger and preference for calorie-dense foods
• Physical activity - many Australian children do not meet the recommended 60 minutes of moderate-to-vigorous activity per day
• Family and home environment - eating patterns, food availability, and parental modelling have a powerful influence on children's habits
• Genetics - family history plays a real role in susceptibility, though it does not make healthy weight impossible to achieve

What Actually Helps: A Family-Based Approach

The evidence strongly supports whole-family approaches over child-focused ones. Children do best when the entire household shifts towards healthier habits together, without singling out one child. Effective strategies include:

Food environment changes

• Make healthy foods the easy, visible choice at home - fruit on the bench, vegetables prepared and accessible
• Reduce the presence of ultra-processed snacks and sugary drinks in the house rather than forbidding them (restriction often backfires)
• Cook and eat together as a family when possible - family meals are consistently associated with better dietary patterns in children
• Avoid using food as a reward or comfort - this can foster emotional eating patterns
• Offer a variety of foods without pressure - children often need repeated exposure before accepting new foods

Moving more

• Prioritise active play over structured exercise - children are more likely to stay active when movement is fun
• Walk or cycle where possible rather than driving
• Limit recreational screen time to no more than two hours per day for school-age children
• Involve children in active activities the whole family does together - swimming, cycling, bush walking

Sleep

Ensuring children get adequate sleep for their age is an often-overlooked part of weight management. School-age children need 9 to 11 hours; teenagers need 8 to 10. Consistent bedtimes and screens out of bedrooms make a meaningful difference.

What Not to Do

Some approaches are well-intentioned but counterproductive, and worth being aware of:

• Do not comment on your child's weight or body - even well-meaning comments can increase the risk of disordered eating and body image issues. Focus on behaviours, not appearance.
• Avoid putting children on restrictive diets - calorie restriction in growing children can impair growth, worsen nutritional intake, and damage their relationship with food
• Do not use shame or embarrassment - these approaches reliably make things worse, not better
• Avoid making food "good" or "bad" - a neutral relationship with food, where all foods can fit, is protective against disordered eating

When to See Your GP

If you have concerns about your child's weight - whether you think they are too heavy or too light - please bring it to your GP rather than trying to manage it alone. I can properly assess growth trajectory, rule out any medical causes such as thyroid problems or other hormonal conditions, and connect you with appropriate support, including dietitian input if needed. The earlier concerns are addressed, the easier they are to manage - and the less likely they are to affect a child's confidence and wellbeing.