Obesity is a complex, chronic condition. It is caused by a variety of physical, environmental, hormonal and psychological causes.
Diagnosing obesity isn’t simply about looking at a number on the scales. Your healthcare team will also consider how your weight is affecting your health and whether you’re living with any conditions linked to excess body fat.
Is BMI enough?
Body mass index (BMI) is one of the tools used to assess weight. It is calculated using your height and weight and can help identify people who may benefit from further assessment.
The usual BMI categories are:
- Healthy weight: 18.5-24.9 kg/m²
- Overweight: 25.0-29.9 kg/m²
- Obesity class 1: 30.0-34.9 kg/m²
- Obesity class 2: 35.0-39.9 kg/m²
- Obesity class 3: 40 kg/m² or above
For people from some ethnic backgrounds, particularly South Asian, Chinese, Black African and African-Caribbean populations, the health risks linked with body weight can occur at lower BMI values. Your healthcare professional will take this into account when assessing your health.
BMI is useful, but it has its limitations. It doesn’t tell us how much of your weight is muscle, where body fat is stored or how your weight is affecting your health. That’s why it should never be used on its own.
Why waist measurement matters
Your healthcare professional may also measure your waist.
Fat stored around the tummy, sometimes called visceral fat, is linked with a higher risk of conditions such as type 2 diabetes, heart disease and fatty liver disease.
Looking at both BMI and waist measurement gives a better picture of your health than using either measure alone.
Looking at the bigger picture
When assessing obesity, your healthcare team will also ask about your medical history, current health and any symptoms you’re experiencing.
They may look for conditions that are commonly linked with obesity, including:
- Type 2 diabetes
- High blood pressure
- High cholesterol
- Sleep apnoea
- Osteoarthritis and joint pain
- Heart disease
- Fatty liver disease
Putting all of this information together helps your healthcare team understand how obesity is affecting your health and decide which treatments are most likely to benefit you.
Thinking about bariatric surgery?
If you’re exploring bariatric surgery, understanding your own health is an important first step. Knowing how obesity is assessed can also help you understand why different treatments are recommended for different people.
Our expert-led Nourished Bariatrics courses are being designed to guide you through every stage of the process, from preparing for surgery to looking after your nutrition in the months and years afterwards.
Join our waiting list to be the first to hear when the courses launches.
