BMI can unfairly discriminate against someone based on their physique, genetics or ethnicity. There are different ranges for BMI based on your ethnicity, but few people know what they are.
A Belgian mathematician named Lambert Adolphe Jacques Quetelet invented the BMI in the 19th century. The samples were based on Scottish and French participants, therefore limiting its ability to be translatable to other populations. The purpose was to create a rapid, easy to use formula for determining degree's of obesity to inform governments when allocating resources. He succeeded in creating a rapid, easy to use formula, however it's effectiveness is questionable. This didn't stop insurance companies in the USA adopting the tool as a way to determine a person's health risk. Therein lies the problem!
BMI is applicable for a lot of people. However, for every person that BMI might accurately describe their health risk, there are equal amounts of people who it does not. There are many individuals who sit within that 'Healthy' BMI range who are metabolically 'Unhealthy'. They may have a higher percentage body fat yet low muscle stores. They may even have a fatty liver, high cholesterol, high blood pressure or insulin resistance; yet they are labelled 'Healthy' due to the use of a 200 year old tool designed by a Mathematician, not a doctor.
Being called 'Obese' can leave a lasting affect for anyone. I've had clients who have a moderate to low percent body fat, exercise regularly, eat reasonably well, have no lifestyle related health conditions, and yet were labelled as 'Obese' due to BMI. These people are often confused or frustrated with this label, and can feel deflated as a result.
So what tools should we use? Skin fold measures are great, however they are limited to the training of the person doing the skin folds. You could have 10 health professionals do skin folds on the same person, and each get different results. They therefore lack consistency. My main issue with using them though, is the level of apprehension for clients coming to see a dietitian already; they then don't need a person (often of 'Healthy' weight person) pinching their fat stores.
The DEXA scan is the gold standard. This is a machine that does a full body scan looking at bone density, fat stores and fat distribution. The problem with the DEXA is the cost and safety. They are an expensive machine which means they are not in every GP Practice or Dietitian clinic. It's also not recommended to scan anymore than once every two years (they are an X-ray after all).
Our preferred option is the InBody 570's Body Composition Analysers. These machines produce a result with a 1-2% variance to the DEXA machine, yet have less radiation than a plane flight. This means they are much safer to scan regularly (great if you're wanting to measure for change in body composition). They are non-invasive, and the scan takes less than a minute. For the best results, the conditions need to be similar; that is, clients need to fast, have voided their bowels and bladder where possible, and wear minimal clothing.
The InBody 570's form part of our tool kit for determining a person's health risk. It provides visceral fat levels, percent body fat, and both muscle and fat distribution (we can monitor where across the body fat and/or muscle was lost/gained). On more than one occasion these machines have vindicated our client's belief that they were not 'Obese'. The results are trackable so we can monitor the changes in our client's body composition.
Why is it important to track changes? With any weight loss intervention, whether its a new eating regime, exercise program or even weight loss surgery; tracking what's ACTUALLY changing it crucial. I have had clients come in for their pre-op appointment before getting weight loss surgery, only then to return 6 to 12 months post op (this is not recommended). Quite often they have lost a considerable amount of weight, yet they are looking frail and report feeling weak. Why? A considerable portion of their weight loss since surgery was muscle. Had they have tracked their changes in body composition more regularly, we could have rescued their muscle loss with changes in protein quantity and distribution. Monitoring zinc supplementation could also have helped.
Any caloric deficit whether it's through surgery, change in diet or increase in exercise, will result in a change in body composition. If you are putting the effort into any of these interventions, I highly recommend tracking your changes accurately. After all, you don't want to achieve a 'Healthy' BMI, only to discover you have been mis-labelled.
To book in for a scan, go to Body Scan | Know Your Body Composition With A Body Scan (cqnutrition.com.au)