Healthy weight and cancer prevention

Try to be as lean as possible without becoming underweight.

After choosing not to smoke, staying in shape is the most important way you can reduce your risk of cancer. Being a healthy weight can also help to reduce your risk of heart disease and Type 2 diabetes.

What is a healthy weight?

One of the easiest ways to check if you’re a healthy weight is by measuring your BMI. This calculates whether you're in the healthy weight range for your height, so it's a useful guide for most adults.

A healthy BMI for men and women is between 18.5-24.9. We should try to maintain a healthy weight that is as low as possible for ourselves.

For some people, it might not be appropriate to reach the lowest BMI in the healthy weight range.

Weight and cancer risk – the evidence

The evidence that being overweight increases the risk of cancer is stronger now than ever before. In fact, scientists believe that, after not smoking, maintaining a healthy weight is the most important thing you can do for cancer prevention.

There is strong evidence that being overweight increases the risk of the following cancers:

• Bowel
• Oesophagus
• Pancreas
• Kidney
• Endometrium (womb lining)
• Breast (in postmenopausal women)

Being overweight also probably increases the risk of gallbladder cancer.

Scientists believe there are several reasons for the link between body fat and cancer. For example, research shows that fat cells release hormones such as oestrogen, which can increase the risk of cancers such as breast cancer.

Studies have also shown that fat, particularly if stored around the waist, encourages the body to produce 'growth hormones'. Having high levels of these hormones is linked to a greater risk of cancer.

For this reason, WCRF UK recommends that you measure your waist as well as check your BMI to find out if you are in the healthy weight range.

Tips for maintaining a healthy weight

• Choose foods that are lower in energy density. 'Energy density' is a term which describes how many calories foods contain relative to their weight. To maintain a healthy weight, it's best to choose lower energy-dense foods, which have fewer calories but are filling because they contain plenty of water and fibre. One step is to avoid fast food and sugary drinks.
• Keep an eye on portion size. Too much of almost any food can cause us to gain weight, so only eat when you’re hungry and try to stop before you feel too full. Opt for smaller serving sizes to make it easier to control how much you’re eating.
• Be physically active. Keeping active helps us to burn calories, which are stored as fat if they are not used. Try to incorporate some physical activity into your daily routine and build up the amount you do over time. Why not sign up for a WCRF UK running event to help keep you motivated?
• Start today by measuring your waist and BMI. Use our tools and take the first step to staying in shape.

Read all our Recommendations for Cancer Prevention