Posts Tagged ‘ Brown adipose tissue ’

Are You Ready for the Faux-Zombie Apocalypse?


ResearchBlogging.orgThe title of this post is a somewhat obscure reference to an episode of the Nineties Sci-Fi show “Sliders“.  The premise of the show was based on the Multiverse theory in physics, a favourite trope in science fiction.

In “Sliders” a small group of individuals are accidentally set adrift in the multiverse, travelling from Earth to Earth in the hopes of getting home again. The show gave a unique opportunity to explore interesting historical counter factual situations, you know, of the “What if Hitler won the war” variety.

This was handled a little unevenly throughout the 5 season run of the show and some episodes were definitely more plausible than others. One of the less plausible ones sprang to mind when I read this press release a couple of months ago*.

In this episode the intrepid inter-dimensional explorers find themselves on a world where a fat-loss pill turns it’s users into mindless fat craving monsters – coincidentally resembling movie zombies. Cool huh?

Okay, so that isn’t likely to happen. But in a world where approximately a fifth of the population is overweight and a majority of the world populace has more to fear from over rather than under-eating the focus on obesity and methods to combat it is only going to grow. The solutions to obesity likely will need to be multi-pronged, each facet adding an incremental advantage. With this in mind medical solutions have their place alongside education, social and legislative approaches.

One of the medically based avenues open to us is to regulate the activity and/or amount of brown fat in our bodies.

Brief biology lesson: Humans (and other animals) have two main types of fat cell; brown and white. White fat is the regular old fat that we think of, know, and loath. It contributes to unsightly cellulite, increases our risk of various diseases that kill us and is generally something that you want to only have in moderation.

Brown fat on the other hand is a slightly different beast. Like white fat it is a repository of energy, but unlike white fat it is not simply a passive receptacle for these lipids1. Brown fat gets it’s colour (and hence name) from the high density of mitochondria in the cells. The presence of such high numbers of mitochondria allows the cells to channel the force, oh wait that’s a different organelle, sorry. They mean that the cells can burn energy and contribute to thermal regulation, what’s known as Non-shivering thermogenesis.

This type of heat regulation is most important to infants and it was thought that as we grew and matured the brown fat disappeared. This is now known not to be the case, further, manipulation of brown fat in adults may give us a means to burn extra calories and hence reduce our white fat.

Another paper released last year attempts to give a detailed background of the possibility of manipulating brown fat for the purpose of weight regulation. It also notes the potential benefits and drawbacks of this approach and is a very interesting read. Essentially though the idea with utilising brown fat is to increase the body’s basal metabolic rate (the amount of energy you consume while at rest), by doing this we can increase the total number of calories used by the body and effectively burn up the excess calories consumed.

The press released that sparked this post is related to a paper presented at The Endocrine Society’s 93rd Annual Meeting in Boston. It details an investigation into the location of brown fat in the adult body and the mechanisms involved in the creation of brown fat from undifferentiated progenitor fibroblast cells. The fat tends to be deep within the adipose tissue of the neck and chest as well as mixed in with white fat, hence the thinking that we lost it as we age – it’s not easy to find. This incremental step in understanding gives us another tool that may be used to increase our proportion of brown fat cells and thus increase our metabolic capability.

Previous work by the same lead author has correlated amount of brown fat with BMI, finding an inverse relationship. The implication here is that a larger amount of brown fat does contribute to a higher metabolic rate and there for allows some individuals to avoid long term accumulation of fat, confirming that this is a potentially viable approach to weightloss. The numbers of this study were pretty low though and I’m not sure how clinically relevant this finding is.

The authors caution however that benefits may be modest, the lead author is quoted:

“As powerful as brown fat could be at burning calories, we can easily out-eat the benefit.”

So don’t be looking at this as a panacea for obesity, as noted above we will likely have to tackle this problem from multiple sides. Those who view our increasing dependence on drugs and medical interventions with suspicion may not be happy with treating obesity in this fashion2, but it is such a growing problem we should use every tactic at our disposal to reduce the risks associated with this threat to our health.

So, bring on the human experimentation and lets hope the reducing of people to vacant fat-starved cannibals is kept to a minimum.

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Cypess, A., Lehman, S., Williams, G., Tal, I., Rodman, D., Goldfine, A., Kuo, F., Palmer, E., Tseng, Y., Doria, A., Kolodny, G., & Kahn, C. (2009). Identification and Importance of Brown Adipose Tissue in Adult Humans New England Journal of Medicine, 360 (15), 1509-1517 DOI: 10.1056/NEJMoa0810780

Tseng, Y., Cypess, A., & Kahn, C. (2010). Cellular bioenergetics as a target for obesity therapy Nature Reviews Drug Discovery, 9 (6), 465-482 DOI: 10.1038/nrd3138

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* Yes, I really am that lazy.

1. Yes again, I know that’s a gross over simplification. White fat does stuff too.

2. I have no evidence of this but I’m sure they’re out there.

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