Cancer and Obesity
Does obesity increase the risk of cancer?
Obesity is measured in terms of body mass index (BMI).
BMI determines whether weight is in healthy range or is overweight or obese.
BMI = weight/height squared; For example, for a person weighing 80 kg and 170 m tall, BMI = 27.6
One is underweight if the BMI is less than 18.5
A person is said to have a healthy BMI if it is between 18.5 and 24.9
When BMI is between 25 to 29.9, it is defined as overweight
When the BMI is 30 or higher, the person is said to be obese.
How does obesity increase the risk of cancers?
Obesity increases the risk of cancer in a few ways:
- Fat tissue in the body produces excess amounts of oestrogen. High levels of oestrogen increases the risk of breast, endometrial, bowel and some other cancers.
- Obese people have high levels of insulin and insulin-like substances in their blood. These substances may promote the development of certain tumors.
- Fat cells produce hormones called adipokines that may stimulate growth of certain cancers.
- Obese people are said to have chronic low-level inflammation which is associated with increased risk of cancer.
What are the cancers associated with obesity?
Obesity is associated with increased risk of cancer of:
- Colon and rectum
- Breast (after menopause)
What other diseases are associated with obesity?
Besides cancer, obesity is a major risk factor for many diseases including:
- Heart diseases
- High blood pressure
- Sleep apnoea
- Gallbladder problems
How common is obesity?
Obesity has become an epidemic globally. According to World Health Organization (WHO):
- Obesity has more than doubled since 1980 worldwide.
- In 2014, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 600 million were obese.
- 39% of adults aged 18 years and over were overweight in 2014, and 13% were obese.
In the USA, about two-thirds of adults and nearly one-third of children are either overweight or obese.
Australia is today ranked as one of the fattest nations in the developed world. If weight gain continues at current levels, by 2025, close to 80% of all Australian adults and a third of all children will be overweight or obese (MODI).
If the obesity epidemic continues at the present state, despite the new advances in diagnosis and treatment of cancers, the number of cancer cases will increase significantly taking also into account the increasing life expectancy of people all over the world.
According to WHO, one-third of all cancer cases are preventable. The best way to prevent cancer is by adopting healthy lifestyle like eating a healthy diet, exercising regularly, maintaining a healthy body weight, quitting smoking, and reducing/quitting alcohol.