obesity

Losing Weight May Also Reduce Risk of Cancer

David Mendosa Health Guide November 01, 2007
  • We already had several good reasons to lose weight. Now we have another one.

    The overwhelming majority of those of us adults who have been diagnosed with diabetes are overweight or obese. The U.S. Centers for Disease Control and Prevention says that 85.2 percent of us are either overweight or obese, of which 54.8 percent of us are obese. This is based on large surveys of Americans with diabetes.

    We have long known that being overweight leads to heart attacks and strokes, the major cause of death in this country, especially for people with diabetes. But I certainly didn’t know that taking off extra pounds is also the best way to avoid the number 2 killer, cancer.


    A huge new study of the World Cancer Research Fund and the American Institute for Cancer Research, Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective, came to definitive conclusions about the link between weight and cancer.

    Its very first conclusion was the importance of maintaining a healthy weight in preventing cancer as well as other chronic diseases.

    There’s a lot more in the 537 page report summarizing the scientific evidence. The panel reviewed all 7,000 published cancer studies and determined that the evidence shows that being overweight increases your risk of cancer, nay even causes it. It goes well beyond a mere association or correlation. The panel carefully studied all the evidence, as detailed in chapter 3, "Judging the Evidence."

     

    Box 2.4 on page 39 presents a good case for a causal mechanism, namely increased hormone levels. "Obesity influences the levels of a number of hormones and growth factors," it states there. "Insulin-like growth factor 1 (IGF-1), insulin, and leptin are all elevated in obese people, and can promote the growth of cancer cells. In addition, insulin resistance is increased, in particular by abdominal fatness, and the pancreas compensates by increasing insulin production. This hyperinsulinaemia increases the risk of cancers of the colon and endometrium, and possibly of the pancreas and kidney. Increased circulating leptin levels in obese individuals
    are associated with colorectal and prostate cancers."

     

    There's lots more, but this is probably enough incentive for just about anyone to seek a low normal weight.

     

    “The single message is how much obesity affects cancer risk," stated panel member W. Philip T. James, MD, DrSc, chairman of the London-based International Obesity Task Force. “The message is absolutely clear as a bell: The relation of cancer to obesity is so robust, it is going to rank close to the smoking problem in America pretty soon.”

    The panel’s first recommendation is unequivocal: “Be as lean as possible within the normal range of body weight.” That means, the panel explains, that our body mass index (BMI) should be “towards the lower end of the normal BMI range.”

    That’s low indeed. The “Standard BMI Calculator” of the U.S. Department of Health and Human Services says that a normal weight is a BMI of 18.5 to 24.9.

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    You can also calculate your BMI without a computer. Here’s one way:


    Multiply your weight in pounds by 703.
    Divide that answer by your height in inches.
    Divide that answer by your height in inches again.

    That's not too easy. But right here at HealthCentral.com we have probably the easiest one to use.

     

    Does this mean that we should shoot for the lowest end of the range? If so, the new study would have me shoot for a weight of 146 pounds (66.2 kilograms), since I’m 6 foot 2.5 inches (189.23 centimeters) tall.

    Wow! That would mean that I still have a long way to go, even after continually losing weight for the two years I’ve been using Byetta.

    Almost all of us have a long way to go in losing weight in order to minimize our risk of cancer and other diseases. For example, the BMI of 18.5 for someone who is 5 foot 7 inches tall would be a weight of 118 pounds.

     

    Still, a BMI of 18.5 might well be too low. The panel says to aim for the low end of the normal BMI range, not actually the lowest. I also note, for example, that the National Heart Lung and Blood Institute "Body Mass Index Table" only goes down to a BMI of 19. Aiming for 19.0 also fits in with previous research, one expert tells me.

     

    Not many people are there yet. But these are the goals that we need to aim at.