Reduce your risk of developing breast cancer after the menopause by maintaining a healthy weight throughout your life

  • The more weight you gain in your life, the higher your risk of developing breast cancer after the menopause
  • By keeping to a healthy weight, you can reduce your risk of breast cancer after the menopause

How does my weight affect my risk of developing breast cancer?

Your risk of developing breast cancer increases if you are overweight or obese after the menopause. The menopause is when you stop having periods and are not able to get pregnant naturally.

In the UK the average age of the menopause is 51, but it can range from 45 to 55 years of age. Putting on weight throughout adulthood also increases your risk of developing breast cancer after the menopause.

The more weight you gain over the course of your adult life, the higher your risk. Being obese when diagnosed with breast cancer can increase the risk that your cancer will recur (come back after treatment). It can also reduce your chances of surviving the disease.

Research also suggests that being overweight or obese before the menopause slightly reduces your risk of developing breast cancer before the menopause, although these links are not as clear.

But it’s important to know that breast cancer risk increases with age, so the effect of breast cancer risk is most important after the menopause, which is when four out of five breast cancers occur. Keeping to a healthy weight throughout your life will reduce your risk of developing breast cancer at this time.

What is my BMI?

The most common way of assessing if you are a healthy weight is by working out your BMI (Body Mass Index). BMI is a measure that uses your height and weight to work out if your weight is healthy.

The table below shows the different ranges of BMI. BMI may not be an accurate way to assess weight for pregnant women or athletes.
BMI table

You can calculate your BMI using the Healthy weight calculator from the NHS.

How much does my weight affect my risk?

The higher your BMI after the menopause, the higher your risk of breast cancer will be. We can show this in the graph below. This shows how many women out of 100 will probably develop breast cancer after the age of 50, depending on their BMI.

Graph showing the estimated number of women out of 100 who will probably develop breast cancer at age 50 or above

Estinated number of women out of 100 who will probably develop breast cancer at age 50 or above

For example:

  • In a group of 100 women with a BMI between 22.5 and 24.9 (within the healthy range), about nine will probably develop breast cancer at age 50 or above. Find out how age affects breast cancer risk
  • But in a group of 100 women with a BMI of 30 or more (in the obese range), about 11 or 12 will probably develop breast cancer
  • So, being obese causes about two or three extra women out of every 100 to develop breast cancer at age 50 or above

Your waist size can also be important to consider. For women, a waist circumference of up to 31.5 inches (80 cm) is considered healthy. A measurement above this is regarded as high. It is likely that carrying more fat around your waist (for example, having a high-risk waist size) slightly increases your risk of breast cancer. This may be true even if your BMI is within the healthy range. You can find out more about waist size from NHS Choices.

So, the higher your BMI after the menopause, the higher your risk of developing breast cancer. By keeping to a healthy weight throughout your life, you can reduce this risk.

How can I keep my weight healthy?

You can keep to a healthy weight by:

We have more information and tips to keep your weight healthy in our blog - Making healthy food choices.

You can also find suggestions for healthy recipes from NHS Choices and from Macmillan Cancer Support.

Taking part in regular physical activity is another way to reduce your risk of developing breast cancer. Learn more about the benefits of being more physically active and ideas to get you started.

If you are worried about your weight, we recommend that you speak to your doctor for advice on how to manage your weight and introduce good habits into your day-to-day life.

Hormones such as oestrogen play important roles in the body. But they may also encourage some breast cancers to grow. After the menopause, the ovaries stop producing oestrogen, so levels in the body drop.

But women who are overweight or obese after the menopause have a higher level of remaining oestrogen in their bodies, which may encourage the growth of some breast cancers. This is because the hormone is also made by fatty tissue.

Being overweight or obese also alters the levels of other hormones, including insulin (which regulates the amount of sugar in your blood) and leptin (which fat cells produce to reduce feelings of hunger). These changes in the mix of hormones in the body might increase the chance of breast cells turning cancerous.

Maintaining a healthy weight throughout your life also reduces the risk of developing a variety of other health problems, such as:

  • heart disease
  • stroke
  • type 2 diabetes
  • dementia
  • other types of cancer

How do we calculate our data?

We base our calculations on evidence that we judge to be reliable and of most relevance to the UK population. We’d like to thank the Statistical Information Team at Cancer Research UK for providing us with baseline data (June 2017).

Note: Some figures have been rounded up for clarity.

References

Reeves, GK et al. (2007) Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335(7630):1134

Health Survey for England 2015: Adult overweight and obesity

Information Standard logo

Information last reviewed: November 2017

Next review due: November 2020

Breast Cancer Now's health information is covered by NHS England's Information Standard quality mark. Find out how this resource was developed.