Creative Health Source

Obesity

Obesity and Breast Cancer

by C. Sowerbutt

Obesity, as you're no doubt aware, is a fairly hot topic these days - for a variety of health-related reasons. Diet - as in how much and how often we eat affects development of breast tumors. For example, it is known to lead to chronic illnesses including heart disease and diabetes, which are currently on the rise at epidemic rates in North America. Not surprisingly, perhaps, exercise is tied into this. However, obesity is now believed to play a critical role in the development of breast cancer.

A study done at the National Cancer Institute (NCI, United States), presented during the American Association for Cancer Research meeting this October shows that calorie restriction or occasional fasting inhibits breast cancer growth. The study was done in mice, some of which were provided with an unlimited food supply. However, the second group of mice that received a lower calorie intake, or fasted one day per week, lived tumor-free two to three times longer than the obese mice. They rapidly became obese and developed fatal mammary tumors.

They were fed on a "food as desired" basis, on an intermittent basis, or on a caloric restriction/refeeding diet. This study also used mice. In other words, the way we eat has an impact, as well as how much. In a similar vein, a study done at the University of Minnesota shows that periodic calorie restriction - rather than a constant low calorie diet - may provide greater protection against breast cancer. The study investigators also found that the mice that ate as they wanted died at a younger age than the mice in the other two groups. The results showed an 84 percent incidence of breast tumors in the mice that ate without restriction, a 37 percent incidence in the mice that had calorie restrictions, and a 15 percent incidence of breast tumors in the mice who had an intermittent caloric restriction/refeeding program.

While these studies seem to indicate that controlling calorie intakes plays a role in cancer prevention, researchers at the NCI stress the subsequent importance of exercise. Why? Well, calorie restriction reduces the amount of insulin-like growth factor - IGF-1 - by as much as 50 percent. Calorie restriction can result in a decrease in bone density, which can lead to osteoporosis -a significant health problem in post-menopausal women - the same demographic who are increased risk for breast cancer. IGF-1 helps to regulate aspects of development and aging - such as bone density. Exercise helps to minimize the loss of bone density - weight-bearing exercise can help build bone strength.

But for now the message seems to be - less is more - at least when it comes to food. Further dietary studies will continue, and no doubt we will learn a great deal over the coming years.

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