Obesity increases your risk of a multitude of health problems. Cancer is one of them, which can be fatal. Large cohort studies have established the link between obesity and cancer
Obesity just does not increase your risk of cancer but it also increases your risk of mortality due to the dreaded disease.
According to the New England Journal of Medicine, obesity is associated with increased death rates for all cancers including cancer at several particular locations.
Obesity is defined as the excess unhealthy accumulation of fat distribution in the body. To measure your body fat, you use a scale (formula) that tells you whether you are underweight, of normal weight, overweight, obese or morbidly obese.
That formula is called the Body Mass Index (BMI). It is calculated as weight in kgs divided by height in meters squared.
BMI = weight in kgs/( ht in meters)2
This post on obesity and BMI explains how BMI helps you to calculate your body fat status.
That obesity is also a strong risk factor for cancer is an established fact. Being overweight has been linked to 14 to 20% of cancer deaths. Obesity increases your risk of cancer by 1.5 times.
Even women of normal healthy weight who gained 5% of their body weight and moved into the overweight category were associated with an increased risk of developing cancer.
However, how or why obesity and cancer are linked is yet to be established.
It may not sound much, but more than half a million people in the United States suffer from cancer alone every year of which obesity is believed to cause up to 90,000 cancer deaths.
According to the American Cancer Society, obesity increases the risk of many cancers. Cancers related to and associated with obesity are:
- Uterine cancer
- Cervical cancer
- Ovarian cancer
- Postmenopausal breast cancer
- Cancer of Liver
- Esophageal cancer
- Stomach cancer
- Colorectal cancer
- Cancer of Kidney
- Cancer of the Pancreas
- Cancer of the Gallbladder, and
- Multiple myelomas.
How Obesity May Cause Cancer
That obesity and cancer are linked is an established fact. But, how they are linked is yet to be established. Some studies, however, do indicate the following reasons:
1. Due to chronic inflammation
Obesity is associated with chronic low-grade inflammation probably due to the early onset of atherosclerosis. Additionally, there is a strong association between a long-standing chronic inflammation in a particular organ and the development of cancer in that organ.
Chronic low-level inflammation can over time cause DNA damage, which leads to cancer.
For example, study the following associations:
(a) chronic inflammatory bowel disease and colorectal cancer,
(b) chronic gastritis is often seen in obesity and cancer of the stomach and
(c) chronic hepatitis and cancer of the liver
2. Due to high estrogen
Here is another reason postulated for the obesity and cancer association. Fat tissue is important for estrogen production. More the fat tissue more is the estrogen production.
Prolonged exposure to excess levels of estrogen as it happens in obesity, greatly increases the risk of breast cancer. According to a federal study, women who take hormone replacement therapy after menopause not only increase their risk of getting cancer but also are more likely to die of it.
According to the Los Angeles Biomedical Research Institute, women who took estrogen and progesterone were at a greater risk of dying from breast cancer, uterine cancer, and lung cancer. In obesity, due to prolonged exposure to hormones because of excessive fat tissue, the cancer risk is greatly increased.
3. Due to high levels of insulin in obesity
Obese people have high levels of insulin in their blood. This is called hyperinsulinemia or insulin resistance, which leads to the development of diabetes 2.
High levels of insulin can promote the development of cancer of the colon, kidney, prostate, and endometrium.
How to reduce the risk of cancer due to obesity?
Losing weight from your body seems to be the only way to reduce the high cancer risk caused by obesity.
Several studies have endorsed this fact. Obese people who have undergone bariatric surgery to lose weight appear to show a stronger evidence of lowered risk of obesity-related cancers than people who have not undergone this surgery.