Manipulating microbes can control obesity

Published: Wednesday 31 January 2007

-- research carried out by scientists of the Washington University, Missouri, usa, has shown that microbes are responsible for obesity. It's a good news, because the research indicates that manipulating microbes can control obesity. The study was published in the December 21 issue of the journal Nature (Vol 444 No 7122).

The team tracked 12 obese patients at a university weight loss clinic over a period of a year. Half the patients were on a low-calorie, low-fat diet and the other half were on a low-calorie, low carbohydrate diet.

The human gut has two major groups of bacteria--bacteroidetes and firmicutes. Obese people generally have more firmicutes. The group studied faeces of these volunteers and found that as they lost weight, the abundance of the bacteroidetes increased and the abundance of firmicutes decreased.

The group then tried to expand this understanding, using a mouse model.The lab compared the gut microbes of obese and lean mice. The results revealed that the obese animals' microbial community had a greater capacity to digest complex carbohydrates.

The group then tried to see what happens if the microbial group is introduced in mice that did not have any microbes. They found that microbes from obese mice led to a greater fat gain in the recipient. The researchers found that this was due to increased capacity of these microbes to harvest calories from the diet. Though the difference was small, the group feels that over a long period of time, this could lead to the accumulation of fat.
Loopholes But the study does not clarify a few things. For instance, it cannot be said whether some people are predisposed to obesity because they 'start out' with more firmicutes in their guts. The proliferation of the efficient bacteria may be the result of obesity and not its cause. It is also not known if the gut microbes could be manipulated in people in safe and beneficial ways.

The study also does not explain why the body does not send signals to reduce the organism's calorie intake when extraction is more effecient.

The study shows the opposite--that the microbes are more efficient in obese humans who already have the most stored energy. The research also does not reduce the importance of genes, over eating and lack of exercise in weight gain.

The paper opens up an intriguing line of scientific enquiry. According to a comment by Matej Bajzer and Randy J Seeley of the department of psychiatry, Genome Research Institute, University of Cincinnati, the study will help ally microbiologists with nutritionists, physiologists and neuroscientists in the fight against obesity.

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