Friday, May 15, 2009
Let’s start a bit upstream.
First, it is important to understand that fat, or adipose tissue, which is mostly composed of many individual fat cells (adipocytes) is not inherently unhealthy. To the contrary, adipose tissue is absolutely necessary to allow the body to store excess calories during times when we ingest more calories than we expend through activity and resting metabolism. By doing so, adipose tissue acts as a buffer of excess calories, and thus protects other tissues of the body from accumulating fat (i.e. heart, liver, muscle). This notion is best represented by the fact that individuals who completely lack fat tissue (a disorder known as congential lipodystrophy) are very unhealthy and are at great risk of diabetes and heart disease, despite having an athletic and lean appearance.
In other words, fat tissue is essential for health.
Where many people get into trouble is when they have exhausted their body’s ability to store more calories in adipose tissue – we all have a certain threshold to which our fat depots can expand. When we get to that point, our fat cells become so big that they are no longer able to buffer excess calories and thus cannot protect other tissues from fat accumulation and damage. This is when many of the classical metabolic problems of obesity become apparent – increased blood fats, blood glucose levels, etc.
But wait, isn’t losing fat through diet and exercise good for health?
Yes, when we expend more energy (exercise) or reduce the amount of food we ingest (diet), or both, our body draws on our extra stores of energy in our adipose tissue – this process gradually reduces the size of the individual fat cells. That is, fat loss occurs due to a reduction in size of fat cells, not a reduction in the number of fat cells. Not surprisingly, your pants start fitting better. Also, this process makes fat cells more efficient at sucking up excess calories the next time we again eat more than we expend – think Thanksgiving weekend.
This is completely different from the scenario of liposuction, where a whole bunch of fat cells are removed from the body – that is, you reduce the number of fat cells, but the remaining ones don’t get any smaller or healthier – in fact, the opposite may be true (less place to store excess calories than before surgery, so enlargement of those fat cells left behind).
As an example of the lack of health benefit from liposuction, I decided to discuss a paper which was published back in 2004 in the prestigious New England Journal of Medicine. This paper was actually the first paper I discussed with my lab during journal club when I initially arrived at Queen's to do my Master’s back in 2004.
In this study, Klein and colleagues investigated the health effects of liposuction of subcutaneous (under the skin) fat in the abdominal region in 15 obese women.
The liposuction procedure removed between 30- 45 % of the subcutaneous fat in the abdominal region, which was equivalent to approximately 10 kg of fat tissue (see above picture from the study). This represented a 20% reduction in total fat mass – a very substantive change!
However, with regards to the women’s health – the results were rather disappointing, although not surprising given the above discussion. Specifically, 12 weeks after the surgery the women did not show improvements in any of the metabolic markers assessed (insulin sensitivity – a precursor to diabetes, blood pressure, blood glucose, insulin, or lipid levels) as well as any of the other novel markers of disease risk (CRP, adiponectin, IL-6, TNF-α).
Thus, as this paper concludes, while liposuction may be of benefit for cosmetic causes, it should not be considered a clinical treatment for obesity. In other words, surgically removing fat tissue will not bring about the health benefits of weight loss as induced via a negative energy balance (more physical activity and less calorie consumption).
Have a great long weekend.
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Klein, S., Fontana, L., Young, L., Coggan, A.R., Kilo, C., Patterson, B.W., & Mohammed, B.S. (2004). Absence of an Effect of Liposuction on Insulin Action and Risk Factors for Coronary Heart Disease New England Journal of Medicine, 350, 2549-2557
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