Being Overweight Increases Cancer Risk

A new study from Spain of 54,446 people (Prev Med, Jan 17, 2018) shows that:

• Overweight women are 12 times more likely to develop cancer and five times more likely to suffer a heart attack than women of normal weight.

• Overweight men are two times more likely to develop cancer than those of normal weight. The study also showed that only 26 percent of the study population had normal weight. Overweight women who lost 12 pounds in their 40s, and did not put it back on, reduced their risk of suffering cancer by 20 percent.

Excess Weight Raises Cancer Risk The American Association for Cancer Research reports that being overweight is linked to 25 percent of newly diagnosed cancer cases in the U.S. (Am Cancer Soc. Cancer Prevention & Early Detection: Facts & Figures 2017-2018). Adding lack of exercise and a pro-inflammatory diet increases the number to 33 percent. The International Agency for Research on Cancer (IARC) reported that being overweight increases risk for 17 different types of cancers: colon, rectum, esophagus, kidney, breast (women), endometrium, stomach, liver, gall bladder, pancreas, ovary and thyroid, as well as fatal prostate cancer and breast cancer in men, meningioma, multiple myeloma and B-cell lymphoma (N Engl J Med, Aug 25, 2016;375:794-798). Overweight is associated with almost five million cancer deaths each year. Gaining as little as ten pounds between ages 18 and 55 is associated with increased risk for heart attacks, diabetes and the obesity-related cancers later in life (JAMA, 2017;318:255–69).

How Does Weight Gain Increase Cancer Risk? A study from Stanford showed that when people gained six pounds in one month, they suffered unhealthful changes in:

• genes in their cells,

• types of colon bacteria,

• levels of inflammation, and

• heart-attack risk factors. After they lost the added weight, these indicators returned to normal (Cell, Jan 2018).

Increased cancer risk is associated specifically with belly fat (Circulation, 2008;117(13):1658–1667). Depositing fat in the liver can prevent the liver from doing its job of removing excess sugar from the bloodstream. This causes a high rise in blood sugar that causes sugar to stick to all the cells in your body and damage them. Your immunity responds to cell damage in exactly the same way that it responds to invading germs. It produces the same cells and chemicals called cytokines that attack and kill germs to turn on your immunity. Your immunity is supposed to kill germs that invade your body and to help heal damaged tissues, but as soon as the germs are gone and the damaged tissue heals, it is supposed to reduce its activity. If your immunity stays active, it then uses the same mechanisms that it uses to kill germs and heal tissues on you (Archives of Physiology and Biochemistry, 2009;115(2):86–96). This is called inflammation. Your immunity attacks your own genetic material called DNA. Your DNA tells your cells that they are supposed to divide a certain number of times and then die, having been replaced by new cells. However, if the DNA in cells is damaged, the cells can forget to die and keep on dividing. For example, breast cancer cells do not kill a person as long as they stay in the breast. They kill by becoming so abundant that they spread from the breast to invade and destroy your brain, lungs, bones and whatever other organs they invade. The foods that cause the highest rises in blood markers of inflammation include sugar-added foods and drinks, animal fats and fried foods (AGEs). See Anti-Inflammatory and Pro-Inflammatory Foods.

Risk for Many Types of Cancers Can Be Reduced By:

• Restricting calories, which lowers insulin and insulin-like growth factor-I (Frontiers in Physiology, 2012;3(318):1–10), and inflammation (Cancer Research, 2012;72(9):2314–2326).

• Regular exercise (Nature Reviews Cancer, 2008;8(3):205–211).

• Eating lots of vegetables and other anti-inflammatory foods (British Medical Journal, 2006;333(7578):1109–1111; BMJ, Nov 10, 2011;343). 

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