Richard G. Petty, MD

Intestinal Microbes: A Hidden Cause of Obesity

It is no secret that many famous people swear by colonic irrigation. The late Princess Diana used to say that it helped her stay fit and keep her weight steady, though personally I always thought that good genes and regular exercise were the real explanations.

In previous posts I have talked about some of the emerging lines of evidence suggesting that there are at least four previously little recognized causes of obesity:

  1. Stress
  2. Salt intake
  3. Pesticides
  4. Viruses

Following a paper in today’s issue of the journal Nature, it looks as if we shall have to add a fifth: the intestinal microbes that are collectively known as “gut flora.”

We have within us vast communities of microbes that outnumber our own body’s cells by 10 to 1, and may contain 100 times more genes than our own human genome.

We have known for many years that we each contain pounds of these microbes and that they are doing a great deal more than simply sitting there. We have known since the 1950s that many of the microbes are involved in digestion, absorption and immune function. That is one of the reasons why most doctors worry about the unnecessary use of antibiotics: some can knock out the gut flora, sometimes with serious consequences.

It is the first of these – digestion and absorption – that has been attracting attention. Under normal circumstances our bacteria break down many complex molecules like polysaccharides into simple sugars that we absorb and use for energy.

Colleagues from the Washington University School of Medicine in St. Louis have made a remarkable discovery. It seems that the balance of two major families of intestinal bacteria: Firmicutes and Bacteroidetes have a major impact on digestion and obesity. Together these two families constitute 90 per cent of the bacteria in the intestines of humans, and, coincidentally, white mice.

The researchers conducted two parallel studies. In the first they found that as obese people lose weight, the balance between the Firmicutes and the Bacteroidetes changes – the latter increasing in abundance as an overweight person gets slimmer.

The second study used white mice. Here, researchers discovered that the bacteria in the lower intestines of obese white mice were more efficient at extracting calories from complex carbohydrates than the bacteria in the intestines of slimmer mice.

In an earlier study the researchers had shown that the intestines of obese mice had the same depletion of Bacteroidetes as found in the innards of obese humans.

The practical consequence of this finding is immense: it means that if two people are on the same diets and doing the same amount of exercise, one may gain weight and the other stay the same weight. Simply because the person who stayed the same had more Bacteroidetes in his large intestine, extracting fewer calories from the same amount of food. The main reason why his friend gains weight is because he has more Firmicutes and fewer Bacteroidetes.

The researchers suggest that intestinal bacteria could become “biomarkers, mediators and potential therapeutic targets” in the fight against obesity.

I find it impressive that some advocates of natural healing had predicted something along these lines in the early days of the 20th century. I am not too keen on colonic irrigation, though I have many colleagues who use it routinely. But there are many other ways of changing your intestinal flora, including probiotics and prebiotics. You may be interested to look back at a few words that I wrote about them in late August.

I would be happy to detail some other evidence-based strategies that we have used for normalizing intestinal flora.

“A man is not rightly conditioned until he is a happy, healthy, and prosperous being; and happiness, health, and prosperity are the result of a harmonious adjustment of the inner with the outer of the man with his surroundings.”
–James Allen (English Author and Mystic, 1864-1912)

“You cannot poison your body into health with drugs, chemo or radiation. “ Health” can only be achieved with healthful living.”

–T.C. Fry (American Writer on Natural Healing and Originator of the Life Science/Natural Hygiene Course, 1926-1996)

About Richard G. Petty, MD
Dr. Richard G. Petty, MD is a world-renowned authority on the brain, and his revolutionary work on human energy systems has been acclaimed around the globe. He is also an accredited specialist in internal and metabolic medicine, endocrinology, psychiatry, acupuncture and homeopathy. He has been an innovator and leader of the human potential movement for over thirty years and is also an active researcher, teacher, writer, professional speaker and broadcaster. He is the author of five books, including the groundbreaking and best selling CD series Healing, Meaning and Purpose. He has taught in over 45 countries and 48 states in the last ten years, but spends as much time as possible on his horse farm in Georgia.


3 Responses to “Intestinal Microbes: A Hidden Cause of Obesity”
  1. Dr. Elizabeth Barhydt says:

    I agree,
    Death begins in the colon.

    Keeping the colon clean and healthy is very important.
    Diet is important also

    Keep up the good work

    In loving life Dr. Elizabeth

  2. R.Russell says: is manufacturing and
    distributing Bacteroidetes as a natural bacteria supplement for weight loss.

  3. Richard Petty says:

    Thank you for the comments.

    On behalf of my many readers may I ask two questions?
    1. I referred to a short piece that I wrote ( about a conference in London, at which some of the speakers warned that some products on the market did not contain the active ingredients claimed on the label. How do you guarantee the activity of your preparations?
    2. Though I am very familiar with the use of probiotics – I first used them in, I think, 1982 – I am intrigued that you are already distributing Bacteroidetes as a natural bacteria supplement for weight loss. What evidence do you have that they are effective? I could not find anything on your website or from a search of the literature. If you have some data to share I would love to analyze it, and if it’s of good quality I will go ahead and write about it, both here and in my articles.

    Kind regards,


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