Obesity, weight and cancer risk

Our research shows that being overweight or obese is a cause of 12 types of cancer

After not smoking, being a healthy weight is the most important way you can protect yourself against cancer.

There is strong evidence that being overweight or obese is a cause of 12 different types of cancer:

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

Cancer prevention icon for weightOur 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 lose weight.

  • You can check your Body Mass Index (BMI) to find out whether you're a healthy weight for your height.
  • Measuring your waist is a good way to check if you are a healthy shape. Having a healthy waist measurement is linked to a lower risk of cancer, heart disease and Type 2 diabetes.

Mechanism – body weight and cancer

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

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

Storing too much fat can cause insulin resistance (where insulin becomes less effective at controlling blood sugar levels), which 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. Inflammation can promote the growth of cancer by encouraging cancer cells to divide. This inflammatory response may underpin the wide variety of different cancers that have been linked to obesity.

How many adults in the UK are overweight or obese?

  Overweight % Obese % Overweight and obese combined %
England 35 26 61
Wales 36 23 59
Scotland 36 29 65
N Ireland 36 27 63
Figures from 2016–17

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 12 16 28
Wales 15 19 34
Scotland 15 14 29
N Ireland 17 8 25
Figures from 2012–16

Obesity statistics come from the Health Survey for England 2016, the National Survey for Wales 2016–17 for adults and the Welsh Health Survey 2012 for children, the Scottish Health Survey 2016, and the Health Survey Northern Ireland 2016/17.
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