A real gauntlet was thrown down this past week with the publication reviewing the effects of excess weight and morbid obesity on our health. Dr. Walter J. Willett, a professor of epidemiology and nutrition at the Harvard School of Public Health, and 20 co-authors, compiled the 500+ page report, entitled "Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective".

Their meta-analysis of several thousand existing studies found that "excess body fat influences the body's hormones, and these changes can make it more likely for cells to undergo the kind of abnormal growth that leads to cancer." In short, "[t]he risk from excess weight begins at birth." Therefore, obese girls who begin menstruation earlier in life "will have more menstrual cycles. This extended exposure to estrogen is associated with increased risk for premenopausal breast cancer."

This staggering review, which took over five years to develop, indicates that "excess body fat increases the risk of cancer of the colon, kidney, pancreas, esophagus, and uterus as well as postmenopausal breast cancer."Obesity seems poised to become the number one risk factor for cancer in America, as obesity increases and the number of smokers decreases.

What can we do surgically about this?

Well, it appears the weight loss procedures, gastric bypass & gastric banding, can significantly reduce or eliminate many associated comorbidities including diabetes, hypertension, obstructive sleep apnea, and progressive osteoarthritis from excess weight load. In 2006, almost 180,000 patients underwent bariatric surgery of some type.

Last year researchers found that gastric bypass surgery patients were 40% less likely to die from any cause during a mean 7 years of follow-up, compared with the obese controls. It's kind of intuitive that there should be some risk reduction for some of these cancer risks associated with obesity, but I don't believe we have evidence to leap to that conclusion. It might be a very small effect statistically unless it was done on an obese adolescent in whom you'd have decades to track this.

I found a nice collection of review studies re. to Gastric Bypass here at Thinner Times if you're interested.

What about plastic surgery?

Unfortunately there is fairly poor evidence that plastic surgical treatment of weight, whether by resecting excess skin/fat or by liposuction, has an effect on any of these benchmarks. What we can do is cosmetic changes only. A paper from Washington University (St. Louis) published in the New England Journal of Medicine in 2004 found no benefit from high volume liposuction (as you''d expect from weight loss via other methods or diet), where as much as 20% of patients subcutaneous fat stores were removed via liposuction. There have been a small handful of lesser quality papers (like this) suggesting that large volume liposuction may improve glucose control in some type-2 obese diabetics, but the evidence is weak and the studies not really well done (it's a hard subject to study with any uniformity).

However, there is some rationale for a mechanism of how it could work. Large areas of lipodystrophy (fat deposits) are essentially your bodies "batteries" for energy storage. Obese people have a resistance to the effect of insulin mediated in part by their excess fat. In more than 80% of patients who are severely obese and have diabetes and then have gastric bypass surgery, the diabetes is cured. So remove the fat, remove the diabetes, right? Well it turns out it's not quite that simple. It appears the visceral fat (fat inside your abdomen and liver) may be the bigger culprit then the fat outside that you remove with excision or liposuction.

Below is a photo of a visceral fatty deposits in a mouse liver in two different species of mice involved in obesity research. The upper photo shows an "obese mouse", while the lower photo shows the "fit mouse" liver. You can clearly see the "marbling" of the fatty liver.



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