The obesity-cancer connection, and what we can do about it

By Lewis E. Foxhall, MD

It’s almost impossible to get through the holiday season without gaining a few pounds, and for many of us that means we are even more likely to be over our ideal body weight.  Sure, we all want to look good in our clothes, but being obese is not just a condition that affects our appearance.  And in March, during National Nutrition Month, it’s a good chance to talk about it.

Weight gain happens when we take in more calories from food (energy) than we use up through our basic biological requirements and exercise. After a while, enough fat stores up and makes us obese. Our bodies are very efficient at taking in energy and storing it for times when it is hard to find, but in our modern environment this is working against us and our health.  For most of us it is easy to get as much food as we want, and most of us do not need to exert ourselves much for work or daily living activities.

Link between obesity and cancer

The problem with being overweight or obese, as measured by weight and height, is that it raises our risk of chronic diseases like diabetes and heart disease.  But did you know that being obese can actually increase our risk of getting cancer and may even worsen our chances of surviving after a cancer diagnosis?  In fact, the American Cancer Society Cancer Prevention Study II showed significant increases in cancer occurrence in people who are the most overweight.  This link is stronger in some cancer types –including breast cancer after menopause, and cancers of the colon and rectum, pancreas, kidney, esophagus, and endometrium — and can be associated with a major increase in risk. [more]

Being obese appears to be a problem for cancer survivors as well.  Studies have shown worse survival for obese women with breast cancer; obese men with prostate cancer are more likely to have an aggressive form of cancer and it is more likely to come back after surgery.  In light of this more recent data, the American Cancer Society recently released new healthy living guidelines for cancer survivors.

The relationship between body weight and cancer becomes more alarming when we consider just how many people in the United States are overweight or obese. Today, only 1/3 of adults are at a healthy body weight for their height. Another 1/3 are considered “overweight” and the remaining 1/3 are in the “obese” category. (About 17 % of children and adolescents are obese.  These rates are 300% higher than in 1980.)  This puts a huge part of the public at risk for serious chronic diseases and cancer, not just now, but also in the future; statistics show that overweight kids tend to become overweight adults.

What can we do about this problem that increases our risk of cancer and other serious chronic diseases – and threatens our children’s health? First we need to ask the question, “If I lose weight will I lower my risk of getting cancer?”  Research in this area is somewhat limited, although the research that does exist suggests a benefit for some types of cancer. The most reliable comes from studies of people who had weight loss surgery.  In this situation, losing weight did seem to reduce cancer risk. But on average, people undergoing this sort of operation lose 30% of their body weight, compared with about 10% for most other ways of losing weight.   We don’t know if losing less weight also has a benefit. Numerous research studies are underway to better answer this question, but in the meantime, individuals who are overweight or obese should be encouraged and supported in their efforts to reduce weight.

Choosing healthy foods, watching portion sizes, and trying to get regular physical activity are all important. Similar changes are recommended for cancer survivors (assuming there are no medical problems that would interfere or worsen with exercise). In fact, some studies suggest that getting regular physical activity can improve survival for women with breast cancer and people with prostate cancer and colon cancer.

Learn more about recommendations to create a healthier country:

These and other organizations published recommendations to guide us in creating a healthier environment for our children and ourselves.


Changing behaviors through policy and systems change

The causes of the epidemic of obesity in the US are at the most basic level simple, but finding solutions is very complex. 

So what can we do to help people prevent excessive weight gain and maintain a healthy body weight?  Several organizations have offered suggestions for changing policies and systems (decisions and programs) in places like worksites and schools. These kinds of changes are intended to make our environments, the places we spend our time, more conducive to healthy living and following the American Cancer Society guidelines for nutrition and physical activity. These address many parts of life that may reduce barriers that can negatively impact our ability eat well and get the exercise we need.

The National Institutes of Health recently provided a report recommending a broad-based approach, which includes schools, workplaces, and the health care community, to dealing with obesity.  These efforts can be complicated by the arguments over what role government at any level should play in influencing our personal behaviors.  But making it easier for everyone to do the right thing for their health just makes sense, especially if it can help us avoid the huge costs of obesity-related illnesses and save lives.

Several (recommendations have been established. These include:

  • Promoting an active lifestyle and increasing physical activity, especially in children and adolescents
  • Limiting “screen” time: less television viewing, computer time and video gaming
  • Providing safe and secure places to exercise, like giving streets more sidewalks and bike lanes
  • Supporting policies in schools and workplaces that promote physical activity
  • Reducing consumption of sugar-sweetened beverages, and providing healthier alternatives in schools, worksites, restaurants and communities
  • Implementing high nutritional standards for school and government supported food programs and clear, understandable labeling of foods and beverages in stores restaurants, and vending machines
  • Increasing consumption of fruits, vegetables, whole grains, and nuts
  • Limiting sugar, solid fats, and alcohol, and avoiding high-calorie junk food and sweets
  • Encouraging breastfeeding in infants and promoting healthy eating habits in children (let children regulate how much they eat, not “clean your plate”)
  • Assuring children get food containing the minerals and vitamins they need to grow


We must also think about how foods and beverages are marketed to children and adolescents, and ensure that our healthcare systems cover obesity prevention and treatment (some of this is happening as a result of the Affordable Care Act).

This sort of change at the community and population level is not easy and will take a concerted effort by governments, education leaders, businesses, and faith-based groups to succeed.  There is no shortage of well-founded ideas about what to do, but we must find the will to act and sustain the effort.  These changes begin with each of us understanding the threat obesity poses and using our influence at the personal, community, and organizational level to put these ideas into action.


Dr. Foxhall serves on the Board of Directors for the American Cancer Society and the American Cancer Society Cancer Action Network. He is vice president for health policy and is a professor, department of clinical cancer prevention, for the University of Texas MD Anderson Cancer Center in Houston, Texas.

3 thoughts on “The obesity-cancer connection, and what we can do about it

  1. Why are so many newly diagnosed breast cancer patients NOT overweight?
    Obesity is one of many factors, better to focus on what is IN the food!

  2. You can be the correct weight but have too much body fat. If over 50% of cancers can be attributed to obesity, then we have a modifiable solution to eliminating this risk factor. Vitamin D deficiency is also a contributor. Is anyone looking at the Vitamin D levels of the "thin" breast cancer patients? This deficiency as well as reducing obesity are 2 of the most cost effective ways to combat cancer by utilizing these preventive measures. Thank God for mammograms, but you can see that a person is fat and the health professional can test for deficiencies long before a lump or picture of a tumor inform you that cancer exists. Tests are like informing you that when you left the gate open, the cow got out. The problem is, you didn't know you had a cow in the first place because if you knew you wouldn't have left it open! We need to begin to focus on preventive measures as well as testing for cancer.

  3. Prevention may be a good tool to use with children and adults who are not already overweight, but since about 2/3rds of adults are overweight and a third are obese, we need measures available to help them get the weight off and even more important keep it off. ACS as an organization does not even cover bariatric surgery for employees whose doctors have deemed it medically necessary. ACS should lead by example. To quote one of my favorite articles about how rare it is for someone to lose weight and keep it off

    "How rare? Well, this person did the math, and as far as they could tell, two out of 1,000 Weight Watchers customers actually maintain large weight losses permanently. Two out of a thousand. That means if you are fat, you are 25 times more likely to survive getting shot in the head than to stop being fat."
    [URL removed due to blog comment policy]

    Another issue I have is that "diet" or healthy foods cost a lot more than the high sugar processed junk, adding 100s to monthly grocery bills. It is my belief that food companies jack up the price of healthy foods because they know those of us who are desparately fat will pay anything to be thin, meanwhile our children are eating processed junk so they will be the next fat adults. In our society today there is no way to win, we need drastic changes to beat the obesity epidemic.

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