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).

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 a South Asian, Chinese, other Asian, 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.

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, measure around your waist just above your belly button, and divide it by your height, measured in the same units (for example, centimetres or inches).

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

Risks of living with obesity
Obesity is a serious health concern that increases the risk of many other health conditions.

These include:

type 2 diabetes
coronary heart disease
some types of cancer, such as breast cancer and bowel cancer
stroke
Living with overweight and obesity can also affect your quality of life and contribute to mental health problems, such as depression, and can also affect self-esteem.

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.

Other obesity-related problems
Living with obesity can cause a number of further problems, including difficulties with daily activities and serious health conditions.

Day-to-day problems related to obesity include:

breathlessness
increased sweating
snoring
difficulty doing physical activity
often feeling very tired
joint and back pain
low confidence and self-esteem
feeling isolated
The psychological problems associated with living with obesity can also affect your relationships with family and friends, and may lead to depression.

Serious health conditions
Living with obesity can also increase your risk of developing many potentially serious health conditions, including:

type 2 diabetes
high blood pressure
high cholesterol and atherosclerosis (where fatty deposits narrow your arteries), which can lead to coronary heart disease and stroke
asthma
metabolic syndrome, a combination of diabetes, high blood pressure and obesity
several types of cancer, including bowel cancer, breast cancer and womb cancer
gastro-oesophageal reflux disease (GORD), where stomach acid leaks out of the stomach and into the gullet
gallstones
reduced fertility
osteoarthritis, a condition involving pain and stiffness in your joints
sleep apnoea, a condition that causes interrupted breathing during sleep, which can lead to daytime sleepiness with an increased risk of road traffic accidents, as well as a greater risk of diabetes, high blood pressure and heart disease
liver disease and kidney disease
pregnancy complications, such as gestational diabetes or pre-eclampsia, when a woman experiences a potentially dangerous rise in blood pressure during pregnancy
Obesity reduces life expectancy by an average of 3 to 10 years, depending on how severe it is.