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The Link Between Obesity and Cancer Risk?

Being overweight increases cancer risk and growth.

Obesity And Cancer

Two-thirds of American people are significantly overweight or obese, which is a major health crisis. Further, by 2030, it is expected that 85% of all adults in the United States will be overweight or obese.

Obesity is connected to a number of health issues. Overweight or obese people are more susceptible to a variety of ailments, such as diabetes, increased blood pressure, heart conditions, strokes, and cancer, when compared with non obese individuals.

Obesity is identified as a risk factor for thirteen different cancers, which include postmenopausal breast, colorectal, endometrial, esophageal, gallbladder, abdominal, kidney, liver, meningioma, multiple myeloma, ovary, pancreas, and thyroid cancer, in 2016, the International Agency for Research on Cancer (IARC) published a report in which obesity was linked to higher rates of cancer progression and death in people who were previously been diagnosed with certain forms of cancer.

Obesity, for instance, is linked to a 35% increase in breast cancer-specific fatality and a 41% increase in an overall fatality in breast cancer survivors.

Survivors of other types of cancers including colon and rectal cancer, saw a 14% increase in mortality related to obesity. Losing weight has been correlated with decreased risk of numerous malignancies and has a cancer-prevention impact in people who are overweight or obese.

Body mass index (BMI) and waist measurements are used to determine obesity, also known as body fatness.

A person's BMI is calculated by multiplying their body weight (in kilograms) by their height (in meters) squared (usually stated as kg/m2).

BMI provides a fairly accurate measure of obesity than weight alone but your waist and waist to hip ratio measurements are also important to determine body fat.

Overweight And Cancer Risk

In BMI results you are considered:

  • Underweight If it's less than 18.5.

  • Normal if It is within the typical range of 18.5 to 25.

  • Overweight if it is between the range of 25.0 and 30.

  • Obese if it is 30.0 or greater.

Obesity can be classified into the following groups:

  • Class I if BMI between 30 and 35

  • Class II if BMI of 35 to 40

  • Class III if BMI of 40 or above. Obesity in this class is often known as "extreme" or "severe" obesity.

Your BMI, as well as various additional indicators of a healthy body, such as blood chemistry, are commonly used to determine a healthy weight.

Understanding Fat

One way to think about fat is based on location.

There Are Two Types:

  • Subcutaneous

  • visceral.

In most people, about 90% of body fat is subcutaneous and lies just beneath the skin.

The remaining 10% is visceral fat that lies deep within the abdomen surrounding your internal organs like the liver, pancreas and the intestines.

Visceral fat also forms an apron that lies beneath your belly muscles and is called the “omentum”.

Although visceral fat makes up only a small proportion of body fat, it's an important player in a variety of health problems.

Obesity Cancer Risk

Another way to think about fat is at the cellular or molecular level:

There Are Two Types:

  • white fat

  • brown fat

When you are born your fat is mostly the brown type which is metabolically active, used to make energy and heat and protect you from the cold and grow.

As you grow older, you lose the brown fat cells and gain white fat cells which are mainly fat storage cells.

If you eat more calories than you can burn, the excess calories get stored as fat and these white fat cells increase in size and number.

The more excess calories you eat, the more white fat cells accumulate. While this extra fat can serve as an energy reserve it is also capable of multiple other functions that are linked to an increased risk of cancer.

Excess fat cells cause cell damage which mobilizes immune cells to gather resulting in low level chronic inflammation.

These immune cells cause the release of certain proteins called cytokines. These cytokines recruit additional immune cells and there is a continual cycle of inflammation.

Chronic inflammation creates a microenvironment that facilitates the replication and survival of cancer cells. In short, our own immune system, which is trying to combat the effects of damaged adipose tissue, can lay the groundwork for cancer cells to grow and thrive.

Another way fat cells cause increased cancer risk is by altering levels of hormones including growth hormones, sex hormones, insulin, leptin and adiponectin.

For example, leptin is the hormone responsible for making us “feel full.” In obese people, the sensitivity to leptin goes away, and those who are obese keep producing more and more leptin.

Consistently high levels of leptin promotes tumor cell growth and spread. Another hormone called adiponectin which is produced in fat cells is decreased in obese people.

Low levels of adiponectin causes increased insulin levels in the body, poor glucose control, heart disease and increased inflammation.

Imbalance of these and several other hormones overall increases risk of developing cancer as well as how you respond to cancer treatment.

The Link Between Obesity and Cancer Risk


If you and your doctor are comfortable with your current weight and do not wish to lose or gain weight, there are lifestyle changes you can adopt to maintain a healthy weight.

These include:

  • Focus on fresh fruits, vegetables, lean proteins, and whole grains.

  • Eat good quality, nutritious foods in limited quantities that fill you up, such as nuts, seafood, and olive oil, which are high in healthy fats.

  • Limit your intake of highly processed foods such as chips, white bread, cookies, and packaged foods containing artificial additives.

  • Limit or stop drinks like fruit juice, soda, and other high-sugar beverages. Know the sugar and calorie content of your daily coffee, as well as any alcoholic beverages and try to limit that as well.

  • Make it a priority to exercise for at least sixty minutes on most days of each week. Physical activity can be light or vigorous based on your capacity. Go for a jog, attend a fitness class, or take a quick walk or run. You can divide your daily work out into manageable chunks of 10 or 20 mins at a time. Even just a few extra minutes every day can help you reduce your risk of developing cancer.

Working with your medical provider to make healthy adjustments for losing weight is critical.

It can be challenging to drop weight and stay at a healthy weight. Yo-yo dieting puts considerable strain on your body and has been associated with a higher risk of cancer.

Crash diets, or diets that do not provide you with all of the nutrients you need, can be deadly. If you have ever had an eating problem, talk to your doctor before changing your food or activity habits.

REASON TO HOPE: A recent study reveals that an effective program of losing weight with reduced calorie consumption and frequent exercise reduced the risk of obesity-related malignancies by 16% in individuals with type 2 diabetes who are overweight or obese.

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Reason to Hope

There is new research from Brigham and Women’s Hospital that indicates a Western-style diet that is rich in red and processed meat, sugar and refined grains/carbohydrates is tied to higher risk of colorectal cancer through the intestinal microbiota.  Gastroenterology, 2022;DOI:10.1053/j.gastro.2022.06.054 

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