Obesity, body weight and cancer
It's thought that more than one in 20 cancers in the UK are linked to being overweight or obese.
Research has shown that many types of cancer are more common in people who are overweight or obese, including:
- breast cancer, in women after the menopause
- bowel cancer
- womb cancer
- oesophageal (food pipe) cancer
- gastric cardia cancer (a type of stomach cancer)
- pancreatic cancer
- kidney cancer
- gallbladder cancer
This list includes two of the most common types of cancer – breast and bowel cancers - and three of the hardest to treat – pancreatic, oesophageal and gallbladder cancers.
Being overweight can affect the risk of cancer because fat tissues in the body produce hormones and growth factors that can affect the way our cells work.
As a nation, we’re getting fatter
Most adults in England weigh more than is healthy:
- Nearly two thirds of men (64%) and more than half of women (57%) are either overweight or obese
- A quarter (25%) of adults are obese
And these figures are similar in the other UK nations too.
The number of overweight and obese people in the UK is increasing. A study published in the Lancet in 2011 showed that if current trends continue, by 2030 around 4 in 10 people in the UK will be obese.
Small changes can have big effects
Many people gain weight throughout their lives, often without realising it. Even small changes can result in large weight gains over time. For example, by simply eating an excess of 50 calories per day - just half a biscuit - you could gain 5½ pounds or 2½ kg over a year. So in 5 years time you could be over 2 stone or 12½ kg heavier.
The good news is that small changes to your lifestyle can lead to a reduction in body weight. The day-to-day choices we make about our lifestyle have the greatest effect on our weight.
Jeff, a lorry driver from Portsmouth, lost 5 and a half stone by being creative about eating healthily and keeping active while out on the road .
Feeling inspired? Read on for more tips and information about keeping a healthy weight.
Losing weight and keeping it off
The best way to lose weight is to eat healthily, eat smaller amounts and become more active. This will help you to take in less energy (calories) from food and increase the amount of energy you burn off by being more physically active.
In this section, you can read about how to avoid hidden calories and cut down on large portion sizes. Our Ten Top Tips, healthy eating and physical activity sections also have more advice that can help you reach and maintain a healthy weight. You can also ask your GP practice, or a local support group, for help and information.
Ten Top Tips
Cancer Research UK and Weight Concern have joined forces to develop Ten Top Tips for a healthy weight. These tips have been designed to fit into your daily life and are based on the best scientific evidence . Find out about the tips and ways of sticking to them in our Ten Top Tips section.
What is a healthy weight?
You can find out whether your weight is within the healthy range by working out your body mass index, or BMI. Another useful indicator of whether you are a healthy weight is to measure your waist.
The Body Mass Index, or BMI, is a useful tool for finding out if you have a healthy weight for your height. But remember, it is only a guide.
You can work out BMI using a calculator, or use our BMI chart to find out which group you fall into. It shows the underweight, healthy weight, overweight and obese ranges for various weights and heights. Look for your weight on the horizontal lines, and your height on the vertical lines.
To calculate your BMI value exactly, divide your weight (in kilograms) by the square of your height (in metres). This number tells you how healthy your weight is:
- under 18.5 is underweight
- 18.5-25 is healthy weight
- 25-30 is overweight
- 30-35 is obese
- over 35 is very obese.
NHS Choices has a BMI calculator that tells you your BMI and what it means.
In most cases, BMI is a useful tool. But it is not accurate for some groups:
- Children and young people (up to age 18) - doctors use gender and age specific charts to measure young people’s BMIs
- Professional athletes and bodybuilders - BMI doesn’t distinguish between muscle and fat, so people with lots of muscle and low body fat could be classified as overweight or obese.
- Pregnant or breastfeeding women, who need higher fat reserves than usual.
Measure your waist
Measuring around your waist is also a good way to get an idea of whether you are within a healthy weight range. Put the tape measure about an inch above your belly button. For women, a healthy waist measurement is less than 31.5 inches, and for men, it’s less than 37 inches.
Research suggests that the range of healthy BMI and waist circumference should be lower for people of black, Asian, some middle Eastern or mixed ethnicity. But most of this evidence comes from other diseases, like diabetes, rather than cancer.
If you have any questions or worries about your BMI or waist measurement, visit your GP for more advice.
In this section:
- Find out how obesity causes cancer
- Get tips on reducing the risk, including avoiding hidden calories, controlling your portion sizes and encouraging your children to keep a healthy weight
- Learn about the stats and evidence linking body weight to cancer
Question about cancer? Contact our information nurse team