Is this one thing making you fat?

Lose Weight, Lose Fat, Weight Loss, Cure, Obesity, Gut Bacteria, Lactobacillus, Bifidobacterium, Probiotics, Prebiotics

I’ve been secretly obsessed with this for some time now, and incorporated daily habits to help lose fat, improve health and my immune system. Lets start at the beginning…

You’re not completely human!

Gut Bacteria, Probiotics, Prebiotics, Lose Weight, Weight Loss, Cure, ObesityLose Weight, Lose Fat, Weight Loss, Cure, Obesity, Gut Bacteria, Lactobacillus, Bifidobacterium, Probiotics, PrebioticsIn 2003, the National Human Genome Research Institute (NHGRI) in collaboration with a number of partners, announced the successful completion of the Human Genome Project. My wife, Sarah has a degree in Biochemistry, so this subject has always been an area of interest for her.

There are an estimated 20,000 to 25,000 genes in the human genome.That sounds like a lot, but when scientists sequenced the water flea (Daphnia pulex), they found it contained at least at least 30,907 genes.2

Well, we seem a lot more complicated than a water flea, so why don’t we have more genes? It’s because we’ve thrived by having a symbiotic relationship with other microorganisms. A 2016 study by Weizmann institute of science, found that there are about as many human cells, as there are bacteria cells in the body.3

Your gut bacteria impacts your health

Looking only at the gut microbiota (formerly called gut flora), there are at least 1000 different species of known bacteria with more than 3 million genes (150 times more than human genes). Microbiota can, in total, weigh up to 2 kg.4 This “friendly” bacteria can be found in your intestines, and it can have an enormous impact on our bodies.

According to the European Society for Neurogastroenterology & Motility (ESNM), each of us has a unique microbiota, which can have beneficial or negative affects on our health. They help us to:

  • Digest food
  • Produce some vitamins such as B and K
  • Protect us from bad microorganisms
  • Help our immune system, by providing a barrier effect that prevents invasion by pathogens

Such is the importance of the gut bacteria, that it can be considered an organ.

You are what you eat

Many people assume that one carbohydrate is just as good as another, but deep down we’ve probably always had a sneaky suspicion that it’s more complex than that.

It turns out, the reason behind that spare tyre around your belly isn’t as simple as calories in, versus calories out, but what you’ve been eating really counts. For example, depending on your specific gut microbiota, you may be able to extract more calories out of a chocolate bar, than someone else.

According to an article by Francisco Guarner, from the Digestive System Research Unit
Hospital Vall d’Hebron, in Spain,

“the microbiota suppresses intestinal epithelial cell expression of a circulating lipoprotein-lipase inhibitor, fasting-induced adipose factor (Fiaf ), thereby, promoting the storage of triglycerides in adipocytes.”

That last part should catch your attention—in simple terms, it means the actions of the microbiota can increase fat storage.5

So if you’re interested in weight loss, you need to be consuming and feeding the friendly gut bacteria every day.

What happens when the ‘”friendly” bacteria are out of balance?

“Dysbiosis” is the term used to describe the situation where either the normal microbiota are lower in number than should be the case, or are outcompeted by other species of bacteria.

The imbalance of the gut microbiota has been associated with many conditions and illnesses, from obesity to type 2 diabetes, IBS, cancer, Alzheimer’s disease, Parkinson’s disease, Autism, depression and anxiety.

You need to eat good food every day to keep your gut bacteria on the good side of healthy, as large changes to your diet can start to alter microbiome composition within 24 hours.6

Fecal Matter Transplant

Pseudomembranous colitis (PMC) disease, causes diarrhea, colonic inflammation, and sometimes death. It is caused by an overgrowth of Clostridium difficile—usually the result of taking antibiotics, which have subsequently altered the normal microbiota. However, to kill it requires treatment with other antibiotics. There have been clinical trials on patients with recurrent Clostridium difficile infection, to receive a Fecal Matter Transplant (FMT) in order to substantially change their gut microbiota.5

Are we talking about poo? Yes, it is what you’re thinking!

FMT is the process of taking a healthy stool from a doner, and preparing it through filtering, mixing with saline, blending, and other methods. It’s then delivered to the gastrointestinal tract of the patient by colonoscopy or duodenal tube by upper endoscopy.7

The use of FMT for other conditions such as obesity is highly restricted. There is much research being carried out on FMT, and in the future we may find that altering the gut microbiome is the first line of defence for treatment of many common diseases.

There have been a number of studies on mice. In one such study, they transplanted fecal matter from human lean and obese twins, into mice. After 5 days, the mice who were populated with the obese fecal matter were significantly fatter, and had less bacterial diversity compared to the ‘lean twin’ mice.8

A 32 year-old woman who received FMT to treat her Clostridium difficile infection, received a fecal matter donated by her overweight daughter. The woman subsequently gained 34 pounds, and had not been able to lose the weight, despite a medically supervised diet. She had never been obese, prior to the FMT.9

So what can you do about your gut bacteria?

Diversity is key, so every day, I make sure I eat Probiotics from multiple sources (these contain good bacteria) and feed them with Prebiotics (to help them multiply).


Rather than drinking those small, shot sized probiotics, I prefer to get mine from actual living food. For example, a yoghurt stating they have “live cultures”  on the label, most commonly contains the lactic acid bacteria Lactobacillus and Bifidobacterium.

You’re looking for food that has been fermented, but not pasteurised (as that will kill the bacteria). If something has a very long shelf life, then it’s likely to have been pasteurised. The unpasteurised versions are most likely found in the chiller cabinet, and not housed within tin cans (as those are usually sterilised).

You don’t need to make these foods the centre of your dish, but they can be a serving on the side, or as a snack. I personally try to include a portion from the list below in every meal.


  • Yoghurts— chose those that mention they contain the probiotics.

Gut Bacteria, Probiotics, Prebiotics, Lose Weight, Weight Loss, Cure, Obesity

  • Hard cheese—some hard cheeses are good sources if not pasteurised.
  • Unpasturised soft cheeses such as Feta, Brie, Camembert and Blue cheese can contain mould and harmful bacteria, so are best avoided if you’re pregnant or breastfeeding.
  • Kefir—You can make Kefir at home from cow or goats milk and a starter kit of kefir grains. It looks like milk, but tastes quite sour. My wife disliked the taste, so we gave up after a month of making it.

Gut Bacteria, Probiotics, Prebiotics, Lose Weight, Weight Loss, Cure, Obesity


  • Sauerkraut—I love Sauerkraut and eat it daily! It’s fermented cabbage. It’s not so easy to find an unpasteurised version, so we often make our own.

Gut Bacteria, Probiotics, Prebiotics, Lose Weight, Weight Loss, Cure, Obesity

  • Kimchi—this is a spicy red peppered cabbage dish commonly eaten by Koreans. It can be very expensive to buy and not easy to find.

Gut Bacteria, Probiotics, Prebiotics, Lose Weight, Weight Loss, Cure, Obesity

  • Water or brine cured olives—look in the chiller cabinet.
  • Miso—it is a paste made from fermented soya beans and a grain such as rice. Those healthy Japanese love it. It’s commonly made into soup (be careful to put it in after cooking the soup, so as not to kill the friendly bacteria).

Gut Bacteria, Probiotics, Prebiotics, Lose Weight, Weight Loss, Cure, Obesity

  • Fresh sour dill pickles—I haven’t found any of these in the UK, so let me know if you recommend a particular brand.


  • Kombucha—this is made from Symbiotic Culture of Bacteria and Yeast (SCOBY), and can also be created at home. You can buy it in stores in a number of different flavours, as a fizzy drink. You can find them in bottles, in the chiller cabinet.

There are other fermented foods, but the majority don’t retain their live bacteria—for example beer, wine and chocolate.


These are specific carbohydrates that feed the intestinal microflora, and help stimulate the growth of the “friendly bacteria.” They typically contain non-digestible (fermentable) fibre—but not every type of fibre is a prebiotic.

Some common prebiotics are Oligofructose, Inulin, Lactulose, Galactooligosaccharides and Oligosaccharides (also found in breast milk)

Prebiotics are naturally found in many food. Here are some of the top sources:


  • Yoghurt
  • Cheese
  • Kefir

Breast Milk

Vegetables & Legumes

  • Artichoke
  • Asparagus
  • Cabbage
  • Jerusalem artichoke
  • Leeks
  • Legumes including soybean
  • Onions
  • Potato
  • Scallions


  • Apples
  • Bananas
  • Plums
  • Tomatoes

Herbs & Spices

  • Chicory
  • Chives
  • Garlic
  • Dandelion greens (yes, attached to those dandelion flowers in your lawn)


  • Oats
  • Rice
  • Whole wheat


  • Almonds

Resistance Starch

Some of the “friendly” bacteria eat resistance starch. Potato, rice, beans and oatmeal contain resistance starch, which can be increased by cooking and then allowing to cool in the fridge

Growing the (undigestible) resistance starch in this way, has a handy side-effect of reducing the number of calories in that meal. I regularly eat reheated rice at home for that reason.

In addition, it’s worth noting that a raw green banana has more resistance starch in it than a ripe yellow one.

Improve your gut bacteria—make probiotics and prebiotics part of your lifestyle

If you have a medical condition, or are pregnant or breastfeeding, please discuss with your Medical Physician before eating probiotic or prebiotic foods.

I try to eat at least one probiotic and one prebiotic in every meal, to improve health and body composition. Many of these foods taste really nice, so it isn’t that difficult to fit them in.

George D. Choy
Personal Trainer & Calisthenics Instructor
Gymnacity in Oxted, Surrey, United Kingdom

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Related Articles on Weight Loss:


[1] A Brief Guide to Genomics. National Human Genome Research Institute.

[2] John K. Colbourne et. al. The Ecoresponsive Genome of Daphnia pulex. Science 04 Feb 2011: Vol. 331, Issue 6017, pp. 555-561. DOI: 10.1126/science.1197761

[3] Ron Sender, Shai Fuchs, Ron Milo. Revised estimates for the number of human and bacteria cells in the body. bioRxiv 036103; doi:
Now published in PLOS Biology doi: 10.1371/journal.pbio.1002533

[4] Gut Microbiota for Health

[5] 2014 World Gastroenterology Organisation (WGO) Handbook on Gut Microbes

[6] Wu GD, Chen J, Hoffmann C, Bittinger K, Chen YY, Keilbaugh SA, et al. Linking long-term dietary patterns with gut microbial enterotypes. Science 2011 Oct 7;334:105-8.

[7] Marotz CA, Zarrinpar A. Treating Obesity and Metabolic Syndrome with Fecal Microbiota Transplantation. The Yale Journal of Biology and Medicine. 2016;89(3):383-388.

[8] Ridaura VK, Faith JJ, Rey FE. et al. Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science. 2013;341(6150):1241214.

[9] Alang N, Kelly CR. Weight Gain After Fecal Microbiota Transplantation. Open Forum Infect Dis. 2015;2(1):ofv004.

About George D. Choy 92 Articles
Personal Trainer and Calisthenics Instructor at Gymnacity in Oxted, Surrey, UK. Fit over 45. Dad with 2 energetic kids 😄 Passionate about helping people to keep strong, slim and healthy.

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