Being Overweight, Obese, Linked to Cancer Risk, Birth Defects
A large, 16-year study of 900,000 people has shown a strong link between being overweight and having an increased risk of cancer. The study participants were cancer-free before the research began. At the end of the study, researchers determined that extra weight probably caused 14 percent of the cancer deaths in men and 20 percent of cancer deaths in women. The higher rates for women occurred because more women than men are obese.
In the study, people with a so-called “normal” body mass index (BMI) of 18.5 to 24.9 were compared to those with BMIs of 25 to 29.9, considered overweight, and 30 or higher, which is considered obese.
Excess body fat works in a number of ways to increase the risk of cancer. It raises the level of estrogen in the blood, which is thought to increase cancers of the female reproductive system. People who are overweight suffer from acid reflux more often, and this increases the risk of cancer of the esophagus. Extra fat also increases the amount of insulin the body produces, and this can indirectly increase cancer risk as well. Additionally, the more body fat you have, the harder it is to feel and see lumps.
The knowledge that being overweight and obese affects cancer risk isn’t new, but this recent study is the largest and most comprehensive to date.
An increased risk of cancer isn’t the only reason to try to keep your weight in the normal range. A new study published in the journal Pediatrics has shown that women who are obese or overweight before pregnancy have two times the risk of heart defects and multiple birth defects. And obese women had three times the risk of having a baby with a condition called omphalocele, in which the intestines and other organs protrude through the navel.
The American Cancer Society; The New England Journal of Medicine, 24 April 2003; Pediatrics,3 May 2003.