Experiences with
Obesity

How to tell if you're living with obesity

The most widely used method to check if you're a healthy weight is body mass index (BMI).

Body mass index (BMI)

BMI is a measure of whether you're a healthy weight for your height. You can use the NHS BMI healthy weight calculator to find out your BMI.

For most adults, if your BMI is:

below 18.5 – you're in the underweight range
18.5 to 24.9 – you're in the healthy weight range
25 to 29.9 – you're in the overweight range
30 to 39.9 – you're in the obese range
40 or above – you're in the severely obese range

If you have an Asian, Chinese, Middle Eastern, Black African or African-Caribbean family background you'll need to use a lower BMI score to measure overweight and obesity:

23 to 27.4 – you're in the overweight range
27.5 or above – you're in the obese range

BMI score has some limitations because it measures whether a person is carrying too much weight but not too much fat. For example, people who are very muscular, like professional sportspeople, can have a high BMI without much fat.

But for most people, BMI is a useful indication of whether they're a healthy weight.

Waist to height ratio

Another measure of excess fat is waist to height ratio, which can be used as an additional measure in adults who have a BMI under 35.

To calculate your waist to height ratio:

Find the middle point between your lowest rib and your hip bone. This should be roughly level with your belly button.
Wrap the tape measure around this middle point, breathing naturally and not holding your tummy in.
Take your measurement and divide it by your height, measured in the same units (for example, centimetres or inches).

For example, if your waist is 80cm and you are 160cm tall, you would calculate your result like this: 80 divided by 160, which equals 0.5.

A waist to height ratio of 0.5 or higher means you may have increased health risks.

Causes of obesity

Obesity is a complex issue with many causes. Obesity and overweight is caused when extra calories, particularly those from foods high in fat and sugar, are stored in the body as fat.

Obesity is an increasingly common problem because the environment we live in makes it difficult for many people to eat healthily and do enough physical activity.

Genetics can also be a cause of obesity for some people. Your genes can affect how your body uses food and stores fat.

There are also some underlying health conditions that can occasionally contribute to weight gain, such as an underactive thyroid gland (hypothyroidism), although these types of conditions do not usually cause weight problems if they're effectively controlled with medicines.

Some medicines can also make people more likely to put on weight, including steroids and some medicines for high blood pressure, diabetes or mental health conditions.

Treating obesity

The best way to treat obesity is to eat a healthy reduced-calorie diet and exercise regularly.

To do this, you can:

eat a balanced calorie-controlled diet as recommended by a GP or weight loss management health professional (such as a dietitian)
take up activities such as fast walking, jogging, swimming or tennis for 150 to 300 minutes (2.5 to 5 hours) a week

You may benefit from joining a local weight management programme with group meetings or online support. Your GP can tell you about these.

You may also benefit from receiving support and counselling from a trained healthcare professional to help you better understand your relationship with food and develop different eating habits.

If you're living with obesity and lifestyle and behavioural changes alone do not help you lose weight, a medicine called orlistat may be recommended.

If taken correctly, this medicine works by reducing the amount of fat you absorb during digestion. Your GP will know whether orlistat is suitable for you.

A specialist may prescribe other medicines called liraglutide or semaglutide. They work by making you feel fuller and less hungry.

For some people living with obesity, a specialist may recommend weight loss surgery.

SymptomsMedical treatmentsCauses

Adults are generally considered obese if they have a body mass index of 30 or above.

The main treatment for obesity is a reduced-calorie diet and an exercise plan. Less common treatments include weight loss medicines and surgery.

Obesity is usually caused by eating and drinking too much and moving too little.