Patient information
BMI – the body mass index
BMI (Body Mass Index) or body mass index is a calculated value based on your height and weight.
BMI (Body Mass Index) is a value calculated from your height and weight. The index is calculated by dividing weight in kilograms by the square of height in meters (kg/m2). The body mass index can give you indications about your health status and whether there is a reason to discuss weight management treatment with a specialist. BMI is intended for adults (18 years and older).
According to the World Health Organization (WHO), the following BMI categories are used to classify obesity:
BMI < 18.5: underweight
BMI 18.5-24.9: normal weight
BMI 25.0-29.9: overweight
BMI 30.0-34.9: class I obesity
BMI 35.0-39.9: class II obesity
BMI ≥ 40.0: class III obesity
It is important to keep in mind that BMI is not always an accurate indicator of your health, as it does not take body composition into account. However, it is a widely used and convenient tool for screening and classifying obesity. Other measurements such as waist circumference and body fat percentage can be used in conjunction with BMI to give a more complete picture of your health.
Click here to calculate your BMI (Body Mass Index)
Underweight
If your BMI is under 18.5, you are considered underweight. Being underweight can lead to various health problems such as a poorly functioning immune system, decreased bone density, fertility problems, and malnutrition. Being underweight can have various causes such as a poor diet, diseases, and eating disorders.
It is always a good idea to talk to a healthcare professional about any concerns you might have regarding your weight and overall well-being, as they can provide personalised guidance and support.
Normal weight
If your BMI is between 18.5-24.9, you are considered to be at a normal weight. Being within normal weight limits is optimal for health as it reduces the risk of chronic diseases such as heart disease, diabetes, and certain cancers. However, it is important to keep in mind that BMI is not a perfect measure of health and there are other factors that can affect health status, such as genetics, lifestyle, and underlying medical conditions.
It is always a good idea to talk to a healthcare professional about any concerns you might have regarding your weight and overall well-being, as they can provide personalised guidance and support.
Pre-obesity
If your BMI is between 25 and 29.9, you are considered overweight. Overweight can increase the risk of health problems such as diabetes, hypertension, high blood lipids, certain types of cancer, sleep apnoea, and musculoskeletal problems.
It is important to keep in mind that health risks can vary and are related to other factors such as age, gender, and family history.
If you are concerned about your health due to obesity, it is always a good idea to seek help from professionals who have knowledge and experience in working with individuals with obesity.
Obesity I
A BMI over 30 – 34.9 can indicate that you have developed obesity. Increased obesity further increases the likelihood that you will develop complications of overweight and obesity. Complications of obesity can include diabetes, hypertension, high blood lipids, certain types of cancer, sleep apnoea, and musculoskeletal problems.
With increased obesity, many people find it harder to lose weight and maintain weight loss in the long term.
It is important to keep in mind that health risks can vary and are related to other factors such as age, gender, and family history.
If you are concerned about your health due to obesity, it is always a good idea to seek help from professionals who have knowledge and experience in working with individuals with obesity.
Obesity II
If your BMI is over 35 – 39.9, it may indicate that you have developed class II obesity. This means that the obesity is substantial and the likelihood of developing complications of obesity increases even further. Complications of obesity can include diabetes, hypertension, high blood lipids, certain types of cancer, sleep apnoea, and musculoskeletal problems.
With increased obesity, many people find it harder to lose weight and maintain weight loss in the long term.
It is important to keep in mind that health risks can vary and are related to other factors such as age, gender, and family history.
If you are concerned about your health due to obesity, it is always a good idea to seek help from professionals who have knowledge and experience in working with individuals with obesity.
Obesity III
A BMI over 40 indicates severe obesity. This means that the obesity is severe and the likelihood of developing complications of obesity increases even further. Complications of obesity can include diabetes, hypertension, high blood lipids, certain types of cancer, sleep apnoea, and musculoskeletal problems.
With increased obesity, many people find it harder to lose weight and maintain weight loss in the long term.
It is important to keep in mind that health risks can vary and are related to other factors such as age, gender, and family history.
If you are concerned about your health due to obesity, it is always a good idea to seek help from professionals who have knowledge and experience in working with individuals with obesity.
References:
WHO and BMI. https://www.who.int/europe/news-room/fact-sheets/item/a-healthy-lifestyle---who-recommendations
Ng M, Fleming T, Robinson M, et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2014;384(9945):766-81. doi: 10.1016/S0140-6736(14)60460-8
The Global BMI Mortality Collaboration. Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents. Lancet. 2016;388(10046):776-86. doi: 10.1016/S0140-6736(16)30175-1
NCD Risk Factor Collaboration. Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19.2 million participants. Lancet. 2016;387(10026):1377-96. doi: 10.1016/S0140-6736(16)30054-X.
Bhaskaran K, dos-Santos-Silva I, Leon DA, et al. Association of BMI with overall and cause-specific mortality: a population-based cohort study of 3·6 million adults in the UK. Lancet Diabetes Endocrinol. 2018;6(12):944-53. doi: 10.1016/S2213-8587(18)30288-2.
Lu Y, Hajifathalian K, Ezzati M, et al. Metabolic mediators of the effects of body-mass index, overweight, and obesity on coronary heart disease and stroke: a pooled analysis of 97 prospective cohorts with 1·8 million participants. Lancet. 2014;383(9921):970-83. doi: 10.1016/S0140-6736(13)61836-X.
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