Gut bacteria to blame for obesity,says Pune study

Gut bacteria to blame for obesity,says Pune study

NCCS researchers analyse microbial DNA extracted from lean,normal and obese individuals; find vast differences

Just how fat or thin you are is not only genetic or related to environmental and dietary factors. For the first time,Indian scientists have found a link between obesity and gut microflora. “Bacteria in the intestine that help in digestion influence how obese or lean you are,”says Dr Yogesh Shouche,scientist at Pune-based National Centre for Cell Science (NCCS).

Shouche and his colleagues have been working on finding links between obesity and gut microflora for the past four years. Now their findings have been accepted for publication in the September issue of the Indian Journal of Biosciences.

It has been shown by researchers abroad that obese and lean individuals have different gut flora compositions. Shouche’s research corroborates these findings in the Indian context. “Gut microflora can can play an important role in how your body helps you those gain extra kilos,” says Shouche,who collaborated with obesity surgeon Dr Shashank Shah from Ruby Hall Clinic and Dr D R Ranade from Agharkar Research Institute.

“This is the first such study in an Indian population. Obese and lean individuals were classified according to their Body Mass Index and DNA was extracted from faecal samples to identify gut bacteria,which was then analysed and sequenced,” says Shouche.


Our gut is home to trillions of bacteria that help break down foodstuffs that our cells cannot cope with. Together the genes expressed by these intestinal microflora outnumber our own thousands of times,and yet we are still largely in the dark as to what they do. Over 90 per cent of these bacteria,collectively known as the microbiota,come from just two groups—the Bacteroidetes and the Firmicutes.

Research suggests that the proportion of these groups of bacteria is linked to the risk of obesity. The Pune scientists reported comparative analysis and quantification of dominant gut microbiota in lean,normal,obese and surgically treated-obese individuals of Indian origin. Gut microbial diversity was assessed by sequencing 16S ribosomal RNA libraries for each group. At the genus level,bacteria of genus Bacteroides accounted for 40 per cent of the sequences in obese individuals whereas in normal individuals they were less than 10 per cent. Surgery lowers the percentage only marginally. This was further confirmed by qPCR based quantification. A remarkably high archaeal count also highlighted obese individuals.

“Obviously,microbiota are not the whole story behind obesity. We now need to understand how they interact with other things that affect our risk of becoming obese. And there is much we still don’t know about our life-long passengers,such as how they sense and respond to their host’s condition,how they are passed on,or how they are affected by our diet. By answering these questions,scientists could then assess whether actively shifting our bacterial balances could help stem obesity,” Shouche says.