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What to Know about Obesity and Cancer

Jan 09, 2023

Read time: 3 minutes

Woman in jogging clothes kneeling on grass to tie her shoe

Obesity is beating tobacco as the top risk factor for cancer. It is important to learn how obesity can affect cancer care, what types of cancer are linked to obesity, and what everyone can do to lower risk.

What is obesity?

Obesity, meaning a body mass index (BMI) of 30 kg/m2 or greater, occurs when a person has an excess amount or an unhealthy distribution of body fat, according to the National Cancer Institute (NCI). As of 2017, the Centers for Disease Control and Prevention (CDC) reports that 42% of adults in the United States are considered obese. The CDC also finds that age, race, and ethnicity influence the likelihood of obesity, in addition to social and economic disparities.

How can obesity affect cancer risk and care?

Obesity can impact all stages of the cancer continuum. This includes an increased risk of developing cancer, finding and diagnosing cancer, reducing cancer treatment effectiveness, and increasing cancer reoccurrence, as reported by the NCI.

How does obesity increase the risk of cancer?

Obesity raises the risk for cancer in several ways. However, Neli Ulrich, PhD, MS, executive director of the Comprehensive Cancer Center at Huntsman Cancer Institute at the University of Utah, states cancer risk is more about internal fat and body composition than about weight. This research was published in Nature Reviews Gastroenterology & Hepatology. Excess internal body fat can increase the risk for cancer and reoccurrence in many ways:

  • Causing chronic inflammation
  • Contributing to poor gut health
  • Increasing tissue growth and cell mutation
  • Raising sex- and insulin-related hormone levels

What types of cancer are linked to obesity?

Obesity has been found to be a risk factor for 13 types of cancer. This research was published in a 2016 study by the World Health Organization's (WHO) International Agency for Research on Cancer by an expert working group that included Dr. Ulrich. These include all the following types of cancers:

  • Meningioma
  • Thyroid
  • Adenocarcinoma of the esophagus
  • Breast
  • Multiple myeloma
  • Liver
  • Upper stomach
  • Gallbladder
  • Pancreas
  • Kidney
  • Colon and rectum
  • Endometrium
  • Ovary
Diagram of person showing 13 types of cancers associated with obesity

What can people do to lower their risk of cancer and reoccurrence?

Moderate exercise can help reduce inflammation and improve gut health caused by obesity, likely helping colorectal cancer patients live longer. Neli Ulrich, PhD, MS, shares advice about how all patients—no matter their BMI—can improve health and lower risk for cancer:

  • Focus on increasing physical activity instead of weight loss alone
  • Exercise to help reduce fatigue and improve physical function
  • Ask your doctor about specialists, services, and classes that may be available
Infographic for what you need to know about obesity and cancer. Obesity affects every aspect of the cancer continuum from prevention to survivorship and increases the risk of 13 cancer types. Decrease your risk of obesity by maintaining a healthy lifestyle.

Cancer touches all of us.