New Study Reveals That Girls Are Naturally 60% Fatter Than Boys
For the first time, gender-specific Body Fat Reference Curves for boys and girls are to be added to the standard range of UK centile charts of BMI and waist circumference. Based on a two-year study* of almost 2000 children aged between five and 18, these new reference curves for health professionals revealed a startling difference in fat development between the sexes.
One of the authors, Prof Andrew Prentice, from MRC International Nutrition Group, London School of Hygiene and Tropical Medicine, explained:
"These new curves are significant because for the first time they provide a simple and effective method of refining the measure of fat in children. The curves highlight a gender difference which was most evident after puberty where there was a marked divergence in fatness. Girls continue to gain fat but boys gain more muscle and lean tissue. At the age of 18, the girls have proportionately 60% more fat than the boys with the average body fat percentages being 24.6% and 15% respectively."
The study highlights that whilst BMI (body mass index) is widely used as a simple and valuable tool to assess children's height/weight ratio, it does have limitations in assessing normal growth and development which can in turn cause misclassification. Unlike bio-impedance, upon which the study was based, BMI cannot distinguish between increased weight in the form of fat or lean tissue. The new curves directly measure fat, the component of overweight that specifically leads to health problems.
Another author, Dr David McCarthy, Institute of Health Research & Policy, London Metropolitan University will formally launch the paper on Wednesday 7th September at an international symposium at The University of Southampton**, when the study is presented for the first time in the UK.
Another of the research authors, Dr Susan Jebb and Head of Nutrition and Health, MRC Human Nutrition Research added:
"Existing BMI charts do not reveal these important gender differences and natural changes during growth and development. Centile charts for fat go beyond BMI to give a more accurate assessment of body composition and hence associated health risks. By plotting a child's fatness on these centile charts - ideally over a period of time - health professionals will be able to assess the risk of obesity or monitor the impact of treatment."
Dr Ian Campbell, President of the National Obesity Forum added:
"Assessment of weight in children is one of the biggest barriers for healthcare professional when offering proper advice to children and their carers. Additionally, those who were turned off by standing on a set of scales may now be turned back on by the body composition analyser and this can help engage a child in a weight management programme. Overweight kids are largely ignored on the NHS and healthcare professionals are now in an influential position. I hope this report gives health professionals the confidence they need in assessing overweight children and young people."
Awaiting national promotion to healthcare professionals by The Child Growth Foundation, these new curves will be most effective when used with a Tanita BC-418MA Segmental Body Composition Analyser which was pivotal to the study.
Tanita's Body Composition Analysers utilise Bioelectrical Impedance Analysis (BIA) technology to make an indirect measurement of body composition. A safe electrical signal is sent through the body via footplates and hand held electrodes, housed in a single stand-alone unit. Taking only 30 seconds per patient, the simple non-invasive procedure provides consistent and accurate readings.
BIA is based on the fact that lean tissue, such as muscle and blood, contain high levels of water and electrolytes and therefore acts as a conductor of an electrical signal. Fat tissue is comparatively anhydrous and acts as a resistor to the flow of an electrical signal. Increasing levels of fat mass result in a higher impedance value and correspond to higher levels of body fat.
Today, Tanita BIA is recognised as a world leader in practical body composition analysis.
*Jebb S, McCarthy D, Fry T, Prentice AM (2004). New body fat reference curves for children. Obesity Research. (NAASO Suppl), A156.
**Oral Presentation by David McCarthy at 7th International Symposium In Vivo Body Composition Studies, Institute of Human Nutrition, University of Southampton
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