While many of us understand the benefits of maintaining a healthy lifestyle, obesity - when someone has an unhealthy amount or distribution of body fat - continues to be a serious concern in the United States. In fact, the Centers for Disease Control and Prevention (CDC) estimates that more than 39% of adults in the U.S. are living with obesity.
In addition to other controllable health concerns, obesity is a strong risk factor for various types of cancer for both men and women, and also impacts the survival rates for those with cancer. In comparison, genetics is responsible for only 10%-12% of new diagnoses but lifestyle (including unhealthy body composition) is linked to 1/3 of new cancer diagnoses.
“It’s crucial to understand the role of body composition and its relationship to cancer,” says Sami Mansfield, Director of Oncology Wellness at Sarah Cannon Cancer Institute at HCA Midwest Health. “We each have the opportunity to take steps to reduce our risk of cancer and improve survival. Positive lifestyle changes, even small ones, are incredible opportunities to improve your life by reducing your risk of cancer and other chronic health conditions.”
How is obesity calculated?
There are different ways to determine body fat. One term that you probably already know is body mass index (BMI), which uses height and weight to determine body fat. This is a simple equation of height/weight but does not take into account lean muscle so it’s not effective for individuals who do resistance training on a regular basis. A BMI of over 30 is considered to be in the at-risk category and every five point increase over that number creates risk.
Another method, waist circumference, is more effective and increasingly used in healthcare. To measure body fat using waist circumference, measure your waist at the area right above your hip bone. According to the American Institute for Cancer Research (AICR), a waist measurement of 31.5 or above for women and 37 and above for men is considered high risk.
Additionally, an exercise professional who uses skinfold calipers or a machine such a BIA (bioelectrical impedance analysis) can measure body fat. These methods usually incur a cost, but are more accurate for individuals who exercise and are interested in getting a more precise measure of body fatness. The goal percentage of fat varies by age, but approximately 25% is considered to be healthy for an individual around age 50.
What types of cancer are linked to obesity?
According to the American Cancer Society (ACS), obesity is linked with an increased risk of postmenopausal breast cancer, colorectal cancer, endometrial cancer, esophageal cancer, kidney cancer and pancreatic cancer. Obesity has also been associated with other cancer types and diseases, and is correlated to poorer survival outcomes for those with cancer.
In addition, obesity is linked to metabolic symptom, which is being studied for its role in cancer-related mortality. Metabolic syndrome is a cluster of conditions including increased blood pressure, high blood sugar, high waist circumference, increased cholesterol and triglycerides.
What is the link between cancer & obesity?
Adipose (fat storage) tissue is highly metabolically active, releasing hormones, growth factors and signaling molecules that influence the behavior of other cells in the body, including cancerous ones. These molecules, and those listed below, do not necessarily cause cancer themselves, but rather feed the malignant cells, enabling them to grow and multiply.
Hormones can also have an effect on cancer growth. Estrogen, for example, can be produced by fat cells and is known to influence breast cancer. Those with type II diabetes may have increased insulin levels, which has been suggested to influence cancer cell growth. Research has shown that women and men with a high BMI, who often have excess breast tissue and elevated estrogen levels, are at a greater risk for breast cancer.
The proteins interleukin (overstimulated in obese people) and adipokines (cytokines produced by fat tissue and impacted by weight gain), have also been linked to cancer. The over activity of C-terminal binding protein (CtBP), triggered by metabolic imbalance such as diabetes and obesity, often associated with elevated carbohydrate intake, has been connected to an increased risk of breast cancer.
In addition, many individuals with obesity have lower lean body mass, contributing to decreased function and musculoskeletal concerns that can contribute to other chronic conditions.
How can I reduce my risk of obesity-related cancer?
You may reduce the risks of obesity-related cancer by implementing or maintaining a healthy lifestyle. You may do so by:
- Eating a well-balanced diet: Eating well is key to maintaining a healthy lifestyle. Include five servings of vegetables per day, and consider adopting a Mediterranean Diet. Reduce intake of processed foods and beverages, red and processed meats and refined grains.
- Staying physically active: Strive to meet the physical fitness guideline of 150 minutes of moderate or 75 minutes of vigorous exercise each week. Engage in full body strength training three times each week to improve metabolically active muscle.
- Getting enough sleep: Make sure you sleep seven to eight hours every night.
- Take steps to reduce stress-related inflammation: In addition to the steps listed above, strive for positive social interactions, reduce your sedentary minutes per day and seek activities that you find enjoyable.