While obesity is usually associated with cardiovascular issues, a recent study suggests that it is also associated with a higher risk of developing certain cancers. This is believed to be due to extra body fat interfering with hormone cycles as well as glucose and fat metabolism.
For this study, researchers derived population attributable fractions (PAFs) using relative risks and BMI estimates in adults by age, sex, and country. PAFs calculate the contribution of a risk factor to a disease or death. They calculated PAFs using BMI estimates from 2002 and they used GLOBOCAN2012 data to estimate the numbers of new cancer cases that could be attributed to high BMI. In addition, a 10-year lag-period between high BMI and cancer occurrence was assumed.
The researchers found that 5.4% of all cancers in women and 1.9% of all cancers in men were associated with a high BMI. They noted that this was especially true of esophagus, bowel, kidney, and pancreatic cancers. In women, it was also associated with gallbladder, ovarian, uterine cancers, and postmenopausal breast cancers.
They also noted that the effects were mainly seen in people with a BMI of 30 or above and that an increase in BMI by a factor of 1 was associated with a 3% to 10% increase in risk of developing cancer.
The researchers pointed out that abdominal fat was especially dangerous and associated with a higher risk of cancer. This is because abdominal fatty tissue is hormonally active, creating adipose tissue hormones and changing the balance of sex hormones by converting more androgen precursors into estrogen. That, in turn, encourages the development and growth of hormone-related tumors, such as those found in breast cancer and endometrial cancer. Abdominal fat can also lead to an increase in insulin resistance, which leads to increased insulin production, which can encourage cell division and tumor growth.
Researchers from the International Agency for Research on Cancer in France and the University of Queensland in Australia conducted the study. It was published online ahead of print on November 25, 2014, in Lancet Oncology.
Obesity has far ranging negative effect on health. Each year, obesity causes approximately 300,000 premature deaths in the United States. The negative health effects associated with obesity include high blood pressure, diabetes, heart disease, osteoarthritis, metabolic syndrome and sleep apnea.
Improving eating habits and increasing physical activity play a vital role in preventing obesity. It is recommended that we eat five to six servings of fruits and vegetables per day. It also recommended that we get at least 30 minutes of moderate intensity activity every day.