Despite the confines of observational studies on obesity’s link to cancer risk, there seems to be good evidence that larger amounts of body fat are correlated with an added chance of many types of cancer. We know that having too much belly fat, regardless of your weight, is related to an increased risk of colon and rectal cancer. Women with large waistlines after menopause have a greater risk of breast cancer.
That said, the reverse may be true, too. Weight loss may reduce the risk of cancer linked to obesity. We know that when people lose weight, the result is lower levels of hormones -- such as androgens, estrogen and insulin -- that are directly related to cancer.
Specific Cancers Linked to Obesity
According to the National Cancer Institute, being overweight or obese is linked to an increased risk of many cancers, including:
- Breast cancer
- Colorectal cancer
- Endometrial cancer
- Esophageal adenocarcinoma
- Gallbladder cancer
- Gastric cardia cancer
- Kidney cancer
- Liver cancer
- Meningioma
- Multiple myeloma
- Ovarian cancer
- Pancreatic cancer
- Thyroid cancer
Bariatric Surgery, Weight Loss and Cancer Risk
There is strong evidence for a correlation between weight loss and reduced cancer risk from studies of people who have undergone bariatric surgery. Findings show that obese people who have bariatric surgery seem to have reduced risks of obesity-related cancers compared to obese people who do not have bariatric surgery. While the association between overweight, obesity and cancer are not completely understood, there is mounting proof that weight loss may lower the chance of breast cancer in postmenopausal women, more aggressive forms of prostate cancer in men and other cancers, as well.
Sources
National Cancer Institute: Obesity and Cancer.
American Cancer Society: Does body weight affect cancer risk?