6 Nov 2014

Why thin people might thank their gut for their girth

You flush them away without thinking about it, but the bacteria that live in our gut could be key to deciding whether or not we are fat or thin.

New research published today in the journal Cell identifies a new group of gut bacteria that are more common in the guts of thinner people.

Using a unique register of British twins the researchers then demonstrated that our genes play an important role in determining whether we host communities of bacteria that are beneficial to our weight.

“Our findings show that specific groups or microbes living in our gut could be protective against obesity – and that their abundance is influenced by our genes,” said Professor Tim Spector, head of the Department of Twin Research at King’s College London.

The researchers identified a new family of ancient methane producing bacteria called Chistensenellaceae that are found in nearly everybody’s guts, but are more prevalent in the bellies of slimmer people.

They demonstrated the role of the bacteria by transplanting them into the guts of fat mice – and showed they got slimmer as a result.


Efforts to use such ‘probiotic’ treatments in humans haven’t been very successful. But the researchers propose that Chistensenellaceae could form a basis for new probiotics that aid weight loss.

fat and thin twins

“The human microbiome represents and exciting target for dietary changes and treatments aimed at combatting obesity,” said Professor Spector.

Using more than 400 pairs of twins some identical, others non-identical, the researchers were able to show that our genetic background is crucial in dictating how likely we are to host different ratios of beneficial bacteria.

In future, the researchers argue, an understanding of our gut microbes combined with our genetic background could help devised personalised probiotic therapies that could help people predisposed to obesity manage their weight.

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4 reader comments

  1. H Statton says:

    Adverts about probiotic products such as yoghurts and yoghurt-like drinks are all over our television screens and are of course endorsed by slim celebrities.

    Out of curiosity I tried one of these products to assess whether it had any effect, good or bad, for a period of about two weeks. Nothing happened.

    Admittedly I wasn’t expecting any monumental change in the way my body functioned, if there had been the product would not have been on the supermarket shelves in the first place, but I felt no benefit whatsoever (this may simply be because I am not overweight so I did not make a good guinea pig).

    There are many substances in foods that can cause adverse effects when taken in excess. For example, sugar-free mints often contain sorbitol as a replacement sweetener. If consumed excessively sorbitol can act just like a laxative as it draws water into the gut. It is often used in patients as an irrigation solution to help prevent infection e.g. during prostate or urinary tract surgery.

    Xylitol is another sweetener used in foods and it too can cause problems in the form of diarrhoea if consumed in large amounts. I know it is used in a brand of chewing gum but I don’t recall seeing any advice about the risks on the packet.

    Any substance that could potentially change the natural balance of our gut flora has to be treated with due caution. Killing off too much of the commensal (good) bacteria may allow e.g. the yeasts present to flourish uncontrollably going on to cause fresh problems.

    Pathogenic organisms live everywhere but the good bacteria in our bodies keep them in check. But even the good bacteria can cause harm if left unhindered and can become pathogenic opportunists in their own right.

    Although the discovery and use of probiotic bacteria on the whole is a good thing, no sooner is something promoted as being weight-loss inducing it has many people clamouring for the refrigeration section in the shop.

    The obvious concern is abuse of these substances in order to elicit weight-loss. The Foods Standards Agency needs to make it very clear what is in a product and its potential health risks.

    Genetic studies are obviously more than just a good thing. They will provide further insight into our microbial differences and why some of us are lucky enough to generate an environment that encourages Chistensenellaceae to thrive.

    1. H Statton says:

      This is a summation of some facts and figures, do and don’ts of probiotics:

    2. jet199 says:

      There is not a single pro-biotic currently on the market which contains Chistensenellaceae so worries about the supplement industry is not really relevant to this article.

      However if anyone wants to make a lot of money there is now a big gap in the market.

  2. Mark McIntyre says:

    BRILLIANT – no more boring dieting ?
    Signed – Pronounced ‘Porker’ !

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