Talking through BMI centiles with parents

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It can be a difficult thing to tell a parent that their child is over- or under-weight (see module on communication with parents about weight) for further discussion around weight-related communication). If parents are unaware there is an issue, the news could come as a shock and might cause initial upset or anger. Yet this is sometimes a necessary process for parents to go through to recognise the need to change. The following guidance is provided to support you in presenting information about the child’s weight in an informative, yet sensitive, manner. We practiced this approach for many years in the GOALS child weight management programme in Liverpool7 with parents often commenting it was the first time someone had explained to them in “black and white” about their child’s weight.

Avoid sugar-coating information

Whilst you might think it helps parents to “play the issue down” or avoid the term “obese”, our research suggests this can sometimes make things worse8. Whilst parents in our study acknowledged it was difficult to hear, they felt being told the facts about their child’s weight was an important step to help them move forward.      

Being direct doesn't mean being insensitive

You will see in the videos below that it is possible to share difficult weight-related information in a sensitive manner. The following hints may help: 

a) Tone of voice and body language:  By adopting a non-judgemental tone and open body language, you will help parents feel more at ease.    

b) How the information is presented:  Parents need to be given time to digest the facts before any emotional response kicks in. One way this can be achieved is by first explaining BMI and how under/over-weight is identified in a clear, factual manner (before mentioning their individual child).  Once this is done and understood, you then explain where their child fits within this (e.g. by showing where they are on the BMI chart).  

c)  Presenting weight as a changeable component rather than a trait of the child: In video 2 below you will see the practitioner uses the word obese, but she does not specifically say the words “Chloe is obese”. Instead she talks the father through the BMI chart before showing him where Chloe is on the chart. The father is then able to work out for himself what Chloe’s weight status is. If you do feel the need to explain, it may be better to say “Chloe’s BMI is within the obese category” than “Chloe is obese”, since the first example separates Chloe’s weight from who she is as a person, rather than defining Chloe by her weight. This can be encouraging to help her father see weight as a manageable and changeable factor.        

d) Allowing time: You will see in the videos the practitioner talks through the information at a gentle pace and allows pauses throughout the consultation for the parent to digest the information. She also offers parents a chance to ask any questions and helps them feel ok to do so. Silence can feel uncomfortable, but it can also be helpful in allowing time to work through things. It is important to try and resist the temptation to fill any silences with “sugar-coated” information to help the parent feel better.    

The two videos below provide examples of talking through children’s weight, height and BMI with parents. Parents in the videos are actors and children’s names are fictional.  

In video 1, Paula is talking to the mother of a 3-year old boy (Toby), who is worried he is underweight. In this video Paula uses the UK Growth Chart Boys 2-18 years to explain Toby’s height, weight and how this converts to BMI.


In video 2, Paula is talking to the father of a 4-year old girl (Chloe).  Paula uses the UK Growth Chart Girls 2-18 years to explain Chloe’s height and weight, but moves straight to the BMI chart for children aged 2-20 years to explain Chloe’s BMI (because Chloe is overweight, both visually and from the fact her weight centile is a lot higher than her height centile).  


Tracking BMI over time for children who are over weight

As children are still growing, they will reduce their BMI centile by stabilising their weight, or even by putting on weight at a slower rate than they are gaining height. The recommended approach to achieve this is through lifestyle changes to physical activity and diet, as discussed in the modules on Physical Activity and Sedentary Behaviour and Nutrition. Therefore when following-up with parents, you should be encouraged by any reduction in BMI centile, as it will take time for children who are very overweight to achieve a healthy BMI.  

Figure 2 and figure 3 show how it would show on the charts if Chloe (video 2) were to maintain her weight while she continues to grow along the height centiles. Figure 2 shows the height and weight chart, and figure 3 shows the BMI chart.  It can be seen that over a period of 18 months Chloe’s weight drops from > 98th centile to between the 75th and 91st centile. This brings her BMI down from 20.9kg/m2 to 17.1kg/m2, and her BMI centile from >99.6th centile (severely obese) to < 91st centile (healthy). 


Below is a short quiz containing questions on what you have learnt throughout this module. If it takes a number of goes to get all of the questions correct, please note down each score in your logbook in the space provided. The main purpose of this quiz is to embed learning, and provide you with the opportunity to evaluate your learning. Please remember that we are focusing on the effectiveness of this website and not auditing your practice.

Once you have all the questions correct you will be provided with a certificate of module completion.