What Does My Result Mean?
| BMI | Category |
|---|---|
| Less than 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Class I Obesity |
| 35.0 – 39.9 | Class II Obesity |
| 40.0 – 49.9 | Class III Obesity |
| 50.0 – 59.9 | Class IV Obesity |
| 60.0 and above | Class V Obesity |
What is BMI?
First developed in 1972, BMI is a factor used to determine an individual’s risk of disease. BodyFree‘s BMI calculator follows World Health Organization (WHO) guidelines specifically adapted for Australian demographics. While it alone doesn’t accurately measure risk, it’s used along with other metrics for a clearer picture. The higher the figure, the higher the estimated amount of body fat in the person’s body. High body fat is linked to problems like heart disease and type 2 diabetes.
Would you like to calculate your BMI? Simply enter your height and weight into the BodyFree Calculator. This Australian BMI calculator will use this information to give you a calculated result. This trusted body mass index calculator will divide your weight (in kilograms) by your height (in centimetres) squared.
What Affects BMI?
Weight influences BMI because it fluctuates more than height. As such, the same factors that lead to overweight and obesity can also impact one’s BMI.
Unhealthy Diet
Eating a diet high in fat and processed sugar can quickly lead to weight gain. These foods also have very little nutritional value.
Not Physically Active
A lack of physical activity and exercise will lead to less fat burning in the body and an increase in fat stores. Excess fat in the body can lead to numerous health problems including heart disease.
Genetic Factors
A person’s genes can affect the way their body digests food, processes nutrients, and stores calories. In fact, more studies are showing that obesity may be genetic.
Medication Side Effects
Certain medications may cause weight gain. These medications may be used to treat mental health conditions, diabetes or other conditions.
Not Enough Sleep
Many Australians don’t get adequate sleep, causing an imbalance in the hormones that regulate appetite. This increases the likelihood of snacking resulting in increased calories consumed.
Lifestyle Factors
A busy high-stress lifestyle often results in poor food choices that contribute to weight gain. A diet low in healthy nutrients is often the result, leading to increased consumption of convenient store-bought or fast food options over healthier home-cooked meals.
How Do I Read BMI?
A BMI between 18.5 and 24.9 means you are in a healthy weight range for your height. Levels of obesity are considered from a BMI of 30 and above, divided into further classes based on the risk of developing obesity-related health problems:
- Class I: Low-risk obesity (most common in Australia)
- Class II: Moderate-risk obesity
- Class III: High-risk or severe obesity
Our body mass calculator helps Australians understand their health using established medical standards. It is important to remember that BMI on its own doesn’t paint a full picture of one’s health or risk of disease. It provides a guide that allows you and your doctor to assess your level of obesity and together with your medical history determine your risk factors for obesity-related co-morbidities.
Obesity Fast Facts
Proportion of Australian adults classified as obese in 2022
Age range with the highest proportion of adults who are overweight or obese
Increase in the number of adults classified as obese in 2022 from 2011-12
Likelihood of being overweight or obese
(% of Australian adults)
70.8%
69.8%
69.8%
72.4%
85.1%
*Source: Australian Bureau of Statistics
How Do I Maintain or Achieve A Healthy BMI?
Eat a well-rounded healthy diet and avoid skipping meals.
Spend 30 minutes per day on exercise
Get seven to nine hours of sleep daily
Indulge in treats but in moderation
Avoid alcohol and smoking
Consider bariatric surgery as a tool to help you change your eating habits and provide long-term health and weight benefits.
What is a suitable BMI for Bariatric Surgery?
According to the National Health and Medical Research Council (NHMRC), surgery is considered for:
- BMI > 50 (Super obesity)
- BMI > 40 (High-risk/severe obesity)
- BMI > 35 (with comorbidities that can be improved with weight loss)
- BMI > 30 (with poorly managed type 2 diabetes and high cardiovascular risk or are diagnosed or high risk for other obesity-related health conditions)
At BodyFree, your bariatric surgeon will look at your BMI along with your overall health and health concerns to determine if surgery is appropriate. BMI is only one factor considered, your surgeon will also check your medical history and other related test results.
For some people struggling with excess weight, lifestyle and dietary changes may not be enough to deliver long-term weight loss results. Bariatric surgery is a proven method to help people reach a healthier weight and improve their overall well-being.
Our expert team provides the support and guidance needed for weight loss success and improved health. Speak with BodyFree’s health professionals to learn how we can help you achieve your goals.
Frequently Asked Questions
Why are further checks outside of BMI required?
While BMI estimates body fat, it doesn’t account for fat type or distinguish fat from muscle or bone. It must be used alongside other health assessments.
Why are the elderly more prone to obesity?
Age-related loss of muscle and bone mass combined with reduced activity causes increased visceral fat over time.
Is bariatric surgery viable for a BMI under 30?
It’s extremely rare. Surgery is typically recommended only when BMI is 30+ with serious complications.
Does BMI determine the best kind of surgery?
BMI is one factor that would determine which bariatric surgery procedure is appropriate for you, a Gastric Sleeve or Gastric Bypass. Other health conditions such as type 2 diabetes, gastric reflux or high cholesterol will also be factors that impact the surgeon’s recommendations. This is why a detailed consultation with a bariatric surgeon is the best way to determine what is best for you.