Obesity, weight and cancer risk

Our research shows a direct link between being overweight or obese and 11 types of cancer

There is strong evidence that being overweight or obese increases the risk of developing 11 different types of cancer:

How does body weight increase cancer risk?

Our research shows there are several reasons for the link between body fatness and cancer.

For example, we know that fat cells release hormones such as oestrogen, which increases the risk of some cancers, like breast and womb cancer, and promote their growth.

Storing too much fat also encourages the body to produce ‘growth hormones’. High levels of these hormones can promote the growth of cancer cells.

Body fat also stimulates an inflammatory response, which may contribute to the development of several cancers.

Our recommendation is to be a healthy weight – find out how  

What is a healthy weight?

Your weight is a balancing act between the energy you put in (calories from foods and drinks) and the energy you use (for normal bodily functions and what you burn during physical activity).

The average adult man needs around 2,500 calories a day, and an average woman needs about 2,000 calories. If you eat or drink more than your body needs, you will put on weight. The reverse is also true: if you regularly use more energy than you take in, you will start to lose weight.

Checking your Body Mass Index (BMI) is a simple way to find out whether you’re a healthy weight for your height. A healthy BMI for men and women is between 18.5–24.9.

Carrying too much fat around the waist is also linked to a greater risk of cancer, heart disease and type 2 diabetes, so measuring your waist is a good way to check if you are a healthy shape. A healthy waist measurement is less than 94cm/37 inches for men and less than 80cm/31.5 inches for women.

What can we do to reduce our cancer risk?

We could prevent about 1 in 6 of these cancer cases – that's about 25,000 cases a year – if we were all a healthy weight. In fact, after not smoking, being a healthy weight is the most important thing you can do to reduce your cancer risk.

Being a healthy weight can also help to reduce your risk of heart disease and type 2 diabetes.

How many adults in the UK are overweight or obese?

  Overweight % Obese % Overweight and obese combined %
England 35 27 62
Wales 36 24 59
Scotland 36 29 65
N Ireland 34 26 60

Figures from 2015–16

Overweight = BMI between 25 and 29.9

Obese = BMI of 30 and over

In all countries, men are more likely than women to be overweight.

How many children aged 2–15 in the UK are overweight or obese?

  Overweight % Obese % Overweight and obese combined %
England 14 14 28
Wales 15 11 26
Scotland 13 15 28
N Ireland 16 9 25

Figures from 2013–16

Approximately how many cases of cancer in the UK could be prevented if everyone maintained a healthy weight?

Type of cancer Amount of cases
  % Number
Breast (post-menopausal)  16 6,900
Bowel 14 6,000
Womb (endometrium) 38 3,300
Kidney 19 2,100
Oesophagus (adenocarcinoma) 31 1,700
Pancreas 15 1,400
Liver 20 1,100
Prostate (advanced) 9 940
Stomach (cardia) 19 660
Gallbladder 17 300
Ovary 4 280
Total 17 24,700

Obesity statistics come from the Health Survey for England 2015, the Welsh Health Survey 2015 for adults and 2013 for children, the Scottish Health Survey 2015, and the Health Survey Northern Ireland 2015/16. Find out more about preventability estimates or, for more detailed information, download appendix A of our policy report. Find figures on cancer incidence for England, Wales, Scotland and Northern Ireland.
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