Thursday, April 26, 2012

Brown Fat Can Be Made from White Fat

Among the common weight loss approaches are lifestyle change, including diet and exercise, weight loss surgery and obesity drugs. Some of these weight loss approaches may one day be instrumental in converting ordinary white fat into brown fat, the so called “good fat.”

Brown fat has been found to burn energy rather than store it the way white fat does.  So brown fat is more desirable than white fat. Two studies point to ways that the human body may convert ordinary fat into brown fat. One conversion method is through exercise and another involves the hormone, PRDM16.

“In a recent article, Bruce Spiegelman, professor of cell biology and medicine at the Dana-Farber Cancer Institute, and his colleagues report that, in mice at least, exercise can make it [brown fat] appear, by turning ordinary white fat brown. When mice exercise, their muscle cells release a newly discovered hormone that the researchers named irisin. Irisin, in turn, converts white fat cells into brown ones. Those brown fat cells burn extra calories.” Further, Dr. Spiegelman  believes that the human body may convert white fat into brown fat in a similar fashion.

And in a study done by a University of California, San Francisco (UCSF)  group, it was found that in mice, TZDs (thiazolidinediones, such as Actos and Avandia) interacted with the hormone, PRDM16, to cause white fat to be converted into brown fat. TZDs are used to treat Type ll diabetes. However, TZDs have serious side effects, including a risk of heart failure. So while TZDs may not be the most appropriate drug candidate for converting white fat into brown fat, the finding that TZDs can promote the fat conversion could lead to drugs that safely promote the conversion.

With more research, we may one day know how exercise, and what exercise, converts ordinary white fat into brown fat in humans. And some day, we may have a drug that can initiate the white fat to brown fat conversion. Of course, these results would give weight loss services providers more tools in the fight against overweight and obesity. 

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Sunday, April 8, 2012

The Need to Measure Energy Expenditure

Many people believe that in order to manage a process, you must be able to measure elements of the process. And it probably follows that the better you are able to measure process elements, the better you can manage the elements. Well, knowing how many calories are burned. or the energy expenditure (EE) associated with a given physical activity, is important in managing weight.

Accurate devices for measuring energy expenditure are important to both those wanting to manage their weight and those wanting to help others manage their weight. Two devices that measure energy expenditure were compared in a recent study by a group out of Providence, Road Island. The two devices studied were the Stayhealthy RT3 triaxial accelerometer (RT3) and the Sensewear Pro(2) Armband (SWA).

The RT3 is commercially available through Monrovia, California based Stayhealthy, Inc. The RT3 is intended to be used by researchers to collect comprehensive activity measurement data. “The RT3 is the size of a pager and is worn on the waist. It continuously tracks activity through the use of … accelerometer technology that measures motion in three dimensions and provides tri-axial vector data in activity units, metabolic equivalent units (METs) or kilocalories.” The RT3 can be connected to a computer so that measurements taken by the unit can be analyzed.

The SWA is commercially available through Pittsburg, PA BodyMedia, Inc. As indicated, the SWA is worn on the arm. The device uses an accelerometer to measure such as motion, steps and skin temperature.

Although the SWA is reported to be accurate when performing measurements for adult activities, the unit has been found to be less accurate when used to measure children activities. However, a better algorithm is reportedly more accurate.

The Providence study compared the RT3 and the SWA by looking at group and individual results. The researchers concluded that “At the group level, the RT3 and SWA provide similar estimates of PA and sedentary behaviors; however, concordance between monitors may be compromised at the individual level.”

As in other research, the above study indicates that there may be discrepancies in data collected by energy expenditure devices. However, because measuring physical activity for energy expenditure is so important in treating obesity, bariatric service providers should use energy measuring device where appropriate.

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