Being overweight—or I should say over-fat or obese—is due to a myriad of factors, including your genes, lifestyle, and a diet loaded with high-calorie, low-nutrient-dense foods.
By eating these cheap, available high-calorie foods, along with a sedentary lifestyle, over time the calorie energy coming in exceeds the calorie energy expended. The result is increased subcutaneous (under the skin) fat, and visceral (around the organs) fat.
According to the World Health Organization (WHO), there are roughly 1.6 billion overweight adults, 400 million of whom are obese.
It is estimated that if this pandemic problem continues, by the year 2015 2.3 billion adults will be overweight, and 700 million people will be obese. Being overweight or obesity is more than a cosmetic issue.
It is clear that being over-fat and/or obese is unhealthy, as well as a major risk factor for many diseases, including diabetes, high blood pressure, dyslipidemia (high triglycerides, high LDL and low HDL), sleep apnea, arthritis, heart disease, and cancer.
Body fat and estrogen
It is becoming very clear that body fat and obesity are associated with cancers of the breast, liver, prostate, endometrium, esophagus, pancreas, colon/rectum, and kidney. It is also known that your cancer prognosis is also adversely affected by the amount of fat you carry. One of the many links between body fat and cancer is estrogen.
An article in Endocrine-Related Cancer states that adipose tissue (fat) is a major source of estrogen in men and women. In both men and women with excessive body fat, estrogen levels rise due to an enzyme present in fat called aromatase. Aromatase is responsible for converting testosterone into estrogen.
In fact, researchers have found that body fat and obesity are associated with a two- to three-fold increase in aromatization of testosterone to estrogen.
For simplicity sake, there are 2 forms of estrogen that play a role in cancer development: 2-alpha-hydroxyestrone, and 16-alpha-hydroxyestrone. 2-alpha prevents cell growth, 16-alpha causes cell growth and has been found to be high in individuals with breast cancer. Individuals with excess body fat have higher estrogen levels, and the tissues of obese and overweight women are exposed to more estrogen stimulation than the tissues of those who are lean.
In fact, women with estrogen-based breast cancer have elevated 16-alpha-hydroxyestrogen. In men, there is evidence that increased body fat and estrogen are fuels for prostate cancer.
Excessive body fat is toxic and creates fuel that promotes the development and progression of many different cancers. In body fat and cancer part 2, I will discuss the role fat has in the process of inflammation and its (inflammation) role is the development of cancer.
World Health Organization, Obesity and Overweight, http://www.who.int/mediacentre/factsheets/fs311/en/index.htm
Obesity, Androgens, Estrogens, and Cancer Risk; Cancer Research 1982; 42:3281s-2385s
Local estrogen biosynthesis in males and females, Endocrine-Related Cancer (1999) 6, 131-137