Weight that is lower than what is considered as healthy for a given height is described as underweight. At an individual level, BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual.

Height and weight must be measured to calculate BMI. It is most accurate to measure height in meters and weight in kilograms. However, the BMI formula has been adapted for height measured in inches and weight measured in pounds.

For more, see About Adult BMI. Another way to estimate your potential disease risk is to measure your waist circumference. Excessive abdominal fat may be serious because it places you at greater risk for developing obesity-related conditions, such as Type 2 Diabetes, high blood pressure, and coronary artery disease.

Your waistline may be telling you that you have a higher risk of developing obesity-related conditions if you are 1 :. Waist circumference can be used as a screening tool but is not diagnostic of the body fatness or health of an individual. Note : The information on these pages is intended for adult men and non-pregnant women only.

To assess the weight of children or teenagers, see the Child and Teen BMI Calculator. Preventing Weight Gain Choosing a lifestyle that includes good eating habits and daily physical activity can help you maintain a healthy weight and prevent weight gain.

The Possible Health Effects from Having Obesity Having obesity can increase your chances of developing certain diseases and health conditions. Losing Weight Losing Weight If you are overweight or have obesity and have decided to lose weight, even modest weight loss can mean big health benefits.

Underweight If you are concerned about being underweight, please seek a trained healthcare provider.

The Academy of Nutrition and Dietetics Healthy Weight Gain webpage provides some information and advice on how to gain weight and remain healthy. Abdominal obesity is measured using waist circumference. Body mass index BMI is an approximate measure of your best weight for health.

It is calculated by dividing your weight in kilograms by your height in metres squared m 2. BMI is intended for adults only, as children and adolescents are constantly growing.

This makes it difficult to have set values for BMI cut-offs for young people. However, in adults who have stopped growing, an increase in BMI is usually caused by an increase in body fat.

You can use the body mass index BMI calculator for adults to calculate your BMI, provided you know your:. If your BMI is:. For older Australians over the age of 70 years, general health status may be more important than being mildly overweight.

At the population level, BMI is used to indicate level of risk for morbidity disease risk and mortality death rates. Differences in BMI between individual adults of the same age and sex are usually due to body fat, however there are many exceptions to this rule, which is why a BMI figure may not always be accurate.

BMI calculations will overestimate the amount of body fat for:. However, BMI cannot differentiate between body fat and muscle mass. This means there are some exceptions to the BMI guidelines:. BMI calculations used for adults are not a suitable measure of weight for children or adolescents.

The current BMI charts for children have been developed by the US Centres for Disease Control and Prevention. They are useful for the assessment of overweight and obesity in children aged over two years. To calculate a child's BMI, you can use the body mass index calculator for children and teenagers.

However, BMI charts should be used only as a guide to indicate when to make small lifestyle changes, and when to seek further guidance from a doctor or a dietitian. The link between being overweight or obese and the chance you will become ill is not definite. Research is ongoing.

Statistically, there is a greater chance of developing various diseases if you are overweight. This is the dangerous internal fat that coats your organs.

Measuring visceral fat can give a more accurate predictor of some health conditions. These include:. These waist circumference measurements only apply to adults. Overweight and obesity are health conditions of excess weight. Being overweight, especially being obese, can increase your risk of developing serious health problems, including:.

Many of these diseases can be prevented by having a healthy weight and a healthy lifestyle. This includes eating a well-balanced diet and doing regular physical activity.

These benefits can be a lower your risk of getting heart disease or type 2 diabetes. ARE YOU AT RISK? Use the Risk Checker to find out.

Probably the most successful way for weight loss is to make a change to your lifestyle. Try to eat food that is healthier and do more physical activity like exercise.

It will still result in important health improvements. Some people may need a more intensive approach. This can mean having a very low energy diet or taking weight loss medicine. Some people may need bariatric surgery.

This is especially likely in those who are obese or have other risk factors. Waist circumference and BMI are important indicators of risk.

However, many other factors also contribute to disease. Remember, increased physical activity and improved diet will help reduce your risk of disease.

You may also have health benefits that are not directly related to weight loss. Learn more here about the development and quality assurance of healthdirect content. Read more on Heart Foundation website. Together, body mass index BMI and waist size can help work out whether your weight is within the healthy range and whether you are at risk of some chronic conditions.

Find out what each means and how to use them. Read more on Department of Health and Aged Care website. Find out how much weight you should expect to gain at each stage of pregnancy, based on your BMI, and tips on what to eat and how to exercise while pregnant. Read more on Queensland Health website.

Obesity is a major issue in our society, but exercise must be carefully managed. Find out how here. Read more on Exercise and Sports Science Australia ESSA website.