#025 Can You Gain Weight from a Fecal Transplant?

Can You Gain Weight from a Fecal Transplant?

Did you catch the news headlines about the woman who experienced massive weight gain following a fecal transplant from her daughter this past week?  Can this even be true?

Just what is the science behind a fecal transplant and why on earth would anyone ever want to have this procedure done?  In this article I will discuss the answers to these questions.

A Medical Mystery?

An unnamed woman, I’ll call her “UW,” was innocently prescribed a course of antibiotics by her physician to treat an infection she was struggling with.  While the antibiotic cleared up her initial infection the antibiotic caused a new infection, Clostridium difficile colitis.

Clostridium difficile, or “C. diff” for short, is an infection of the colon that can arise after someone has been treated with antibiotics.  As antibiotics can quickly wipe out your good gut bacteria, this then allows very dangerous bacteria, like C. diff, to quickly fill the void and cause a life-threatening infection inside of your colon.

For anyone who has ever experienced C. diff colitis, this can be an especially difficult infection to treat.  Even more antibiotics are given.  Unfortunately, even our most powerful antibiotics often cannot touch this deadly C. diff.

It is in just these most difficult cases when doctors may consider a fecal transplant.

U.W. was just one such patient.  She was in severe pain and her life was in jeopardy from the C. diff infection.  UW opted to get her fecal transplant from her 16 year old daughter.  It just so happened that her daughter was gaining weight at this exact period of time that she needed a fecal transplant.

As this is still a new medical procedure and doctors did not know all of the potential complications, they thought UW’s daughter would make a great fecal donor.  Her physicians then took some of her daughter’s stool and placed it in her own gut.

Her daughter’s stool bacteria were able to fight off her C. diff infection and she was soon cured of this disease.  Unfortunately, over the next 16 months her appetite was uncontrollable and every calorie she took in just seemed to stick.

UW had never had to deal with weight issues before in her life.  Now, regardless of what she did or how she ate she just kept gaining weight.  UW told her gastroenterologist, “from the moment I had the fecal transplant, I felt like a switch flipped in my body.”  The switch was indeed “flipped” and a woman who had never dealt with weight issues before suddenly gained 34 pounds!

Fecal Transplants for C. diff Infections

Fecal transplants for C. diff infections have now gone “main stream.”  For example, the venerable Mayo Clinic even advertises a 90% cure rate for C. diff, with a fecal transplantation.  Based on UW’s experience, doctors now know not to perform fecal transplants from overweight individuals to avoid long-term weight gain.

Could a fecal transplant be used for weight loss?

If a fecal transplant from UW’s overweight daughter made her suddenly become obese, could the opposite also be true?  This is something researchers are looking into right now.  Could transplanting fecal material from the gut of a thin person to an overweight person help them to lose weight?

Gut Bacteria

As there are 10 times more bacterial cells in your gut than the rest of your entire body, could these bacteria play a role in preventing weight gain and even coronary heart disease? Exactly what are these bacteria doing in your gut?

Studies indicate that up to 1,000 different strains of bacteria live in your gut.  These bacteria eat your food, help you digest your food, absorb key nutrients, neutralize toxins, and keep nasty bacterial invaders, like C. diff, away.

Having the right gut bacteria or gut flora can help to protect you against cancer.  When you have gas it may just be a by-product of these bacteria helping you to break down foods like beans.

Depending on your gut flora, you could absorb all or just part of the calories from what you eat.  In other words, with the wrong gut bacteria in place, like in the case of UW, you could absorb more calories from the foods you eat.

Likewise, if you have the right set of bacteria in your gut, you won’t absorb as many calories from food allowing you to eat even more without gaining weight.  Your gut flora can even control your glucose absorption rate, thus influencing your odds of developing diabetes.

Fecal Transplant for Weight Loss

In one the most prestigious scientific journals, Science, Dr. Jeffrey Gordon and colleagues from Washington University published groundbreaking research showing that gut bacteria from a fecal transplant can determine whether mice are lean or obese.

In this study, researchers first created mice with no bacteria in their gut.  At the same time they identified genetically identical human twins of which one twin was thin and the other twin was overweight.  Researchers then injected fecal material from either the thin or the obese human twin into these mice that they had created who lacked any bacteria in their gut.

Dr. Gordon and colleagues found that with the same diet and exercise patterns, the mice who received a fecal transplant from the overweight twin became overweight, like UW, and that the mice who received a fecal transplant from the thin twin twin became lean.

Little Brown Hamster Eating Corn

Oral Version of the Fecal Transplant

Mice share a nasty habit of eating each other’s droppings, also known as coprophagia.  Thus, to further test their theory, researchers then put a thin mouse in a cage with overweight mice and an overweight mouse in a cage with thin mice.

Given the innate habit of coprophagia, they could then test the theory of fecal sharing through the oral route.  As you might guess, the thin mouse eating obese mice droppings became obese.  Likewise, the overweight mouse eating lean mice droppings became thin. This change in mouse body weight was completely independent of their diet and exercise patterns.

Our Diet Determines Our Gut Bacteria

There is more to this study than just measuring the effects of swapping fecal material.  Dr. Gordon and his team also found that mice eating a healthy diet (a diet high in fruit and vegetables while low in saturated fats) could prevent them from becoming overweight if they were exposed to fecal gut bacteria from an obese mouse.

In previous studies, Dr. Gordon and his team showed that within our guts there literally is a “food fight” to see whether the Bacteroides or Firmicutes bacterial strain will dominate.  Thin people tend to have more of the Bacteroides strain and overweight people tend to have more of the Firmicutes strain.

While it may seem like a fecal transplant could be a quick obesity cure, it would still require long-term effort.  For example, to maintain the weight loss after a fecal transplant a person would have to continue to eat a very healthy diet otherwise it would just be a matter of time before the Firmicutes strain took over again and the person gained all of their weight back.

Indeed, Dr. Gordon and colleagues have also shown that within just 24 hours of eating a Western Diet (high sugar and high saturated fat), the bacteria in the gut could be shifted back to Firmicutes despite a fecal transplant.  Thus, if you did not want to change your eating habits you would need a daily fecal transplant to stay thin.

I suspect few people would sign up for a daily fecal transplant procedure.  However, if you could put fecal material from a thin person into a supplement then perhaps this is something you could take every day…

Could antibiotics really be a “fat drug?”

Along the same subject of gut bacteria and weight gain, animal breeders have known for years that if animals are given just a small amount of antibiotics every day that they will gain weight regardless of their diet or exercise patterns.  The data suggest that the healthy gut bacteria killed off by antibiotics allows the bad bacteria to take hold and cause the animal to extract more calories and accumulate more fat from the same diet.

While most of the antibiotics given to animals to fatten them up don’t survive the cooking process, some people feel it is possible that some could survive to your dinner plate.  This small dose in non-organic meat and dairy could be just enough to cause you to gain weight.

Even more plausible is that the course of antibiotics you took last winter may have caused you to gain an extra five pounds that you just can’t seem to get off.  Could our love of antibiotics for livestock and for every cough we humans get be yet another potential cause of the obesity epidemic in the U.S.?

Probiotics and Health

Probiotics have become progressively more popular.  Yogurt and other fermented foods may just give the necessary boost to the healthy bacteria struggling to keep the bad guys out of your gut.

There are also many probiotic supplements now on the market.  Lactobacillus and Bifidobacterium are the most popular as these are the best studied.  Many tout the benefits of ingesting live healthy gut bacteria.

A number of small studies have supported the use of probiotics for various gut, allergy, high cholesterol, depressive, and other conditions.  Currently, however, the strongest data supporting the use of probiotics is to prevent antibiotic-associated diarrhea.  This is an area of science that is still in its infancy and thus, there are still no FDA approved health claims for probiotics.

Personally, I believe we are just at the beginning of our understanding of the role of probiotics.  It certainly makes sense that if we can grow the right bacteria in our gut we just may be able to control many inflammatory and immune related diseases, obesity, and diabetes just to name a few.  Stay tuned, as this will be an exciting area of medical research for many years to come.

Gut Health in China’s Longevity Village

Remarkably, during our stays in China’s Longevity Village we could not find anyone, including the elderly, suffering from constipation, diarrhea, irritable bowel syndrome, or any other gut malady.  They rarely take medications, including antibiotics, and don’t pump their livestock up with antibiotics either.

They eat an extremely high fiber diet.  Almost everything they eat is high in fiber.  How can you not have a healthy gut with so much fiber?

They also love fermented foods like fermented tofu.  Sugar and other simple carbs like bread as well as red meat, and dairy were traditionally absent from their diet.

While they did not intentionally practice intermittent fasting for health reasons, most of the older generations experienced periods of time where they were hungry when food was limited.  These periods of famine may have promoted the healthy gut bacteria which conferred upon them health and longevity.

9 Lessons for Maintaining a Healthy Weight and a Healthy Gut

1. Feed your gut bacteria fiber.

A high fiber diet, consisting of plenty of fruits and vegetables is just what you need to help colonize your gut with the good, disease and obesity fighting bacteria.  High fiber foods are also called “prebiotics” as they create the perfect environment for healthy gut bacteria to thrive. With the right gut bacteria, you can eat more food and be less likely to gain weight or become diabetic.

2. Only take antibiotics when it is absolutely necessary.

Everyone knows that antibiotics are over-prescribed. Not only are we harming our gut health but we may also be gaining weight and creating superbugs from excess antibiotics.  We are just beginning to learn about the potential life-long detrimental effects of just a single course of antibiotics on our gut health.

3. Only eat organic meat and dairy.

Eating non-organic meat and dairy, pumped full of antibiotics, may just be yet another source of unnecessary antibiotics in our diets.

4. Consider probiotics.

Early data are promising for probiotics.  Before considering supplements, I always recommend first getting probiotics naturally from foods such as yogurt or fermented foods.

5. Manage stress.

Studies have shown that when we are under stress it causes the beneficial gut bacteria to die off.  Make it a point to do something for stress each day.  Stress reduction could come in the form of yoga, exercise, being in nature, prayer, mediation, or even just spending time with friends and family.

6. Minimize unhealthy fats.

As shown in the mouse experiment, unhealthy fats in your diet promote the unhealthy gut bacteria, which then could lead to obesity and diabetes.

7. Minimize acid reducing and anti-inflammatory drugs.

These drugs also disrupt healthy bacteria in the gut.  It is important to keep the right acidity in the stomach to promote the right kind of bacteria in our guts.  Likewise, anti-inflammatory drugs, like ibuprofen, can damage the walls of your gut which can also affect good gut bacteria.

8. Minimize the “hunger” carbs.

If possible stay away from sugar or anything else that is like sugar including even “whole wheat” bread, cereals, most pastas, pastries, crackers, processed foods, etc.  These simple carbs, which I like to call the hunger carbs, just make you hungry as soon as you finish eating them.

The disease causing gut bacteria also love these unhealthy carbs as much as we do.  If you love your bread, like me, making your own bread.  You can even try my wife’s “real” bread recipe.

Another option is to try Ezekiel Bread, which is also slowly absorbed and does not result in that sugar surge you get with even traditional whole wheat bread.  Ezekiel Bread can be found in the frozen section of most health food stores.

9. Intermittent fasting.

There are even data supporting the role of intermittent fasting and optimal gut health.  If you already fast for religious reasons, this may be one additional benefit.  Even going without food for just 12 hours seems to increase the balance of Bacteroides to Firmicutes which decreases your likelihood of obesity or diabetes.

Remember, this is early research, but it is fascinating to consider the possibilities.

What do you think about the idea of fecal transplant to control weight gain?  What have you found to help your own gut health?  Do you take probiotics?


Please do not try anything discussed in this article without first speaking with your physician.  There can be risks with anything, even just changing your diet.

Disclaimer Policy: This website is intended to give general information and does not provide medical advice. This website does not create a doctor-patient relationship between you and Dr. John Day. If you have a medical problem, immediately contact your healthcare provider. Information on this website is not intended to diagnose or treat any condition. Dr. John Day is not responsible for any losses, damages or claims that may result from your medical decisions.

  1. I thought that fecal transplant needed to be from a non direct relative (such as husband or wife)….????

    • Great question. This is still an area of active research as this procedure is new.

      Some early studies show a higher success rate when the donor is a relative or spouse compared to a random donor. One added benefit of a donor that lives with the recipient is that no new infections are introduced as people who live together tend to share the same gut flora.

      Here is a good article if you want to read more on this fascinating subject:


      As I don’t give any medical advice online, please continue to work with your doctor.

      Hope this helps!

      Dr. John Day

  2. I am wondering what you think about taking the non pastureized apple cider vinegar in water every day?

    • Thank you for your question! I do like vinegars as they lower glucose and insulin and there are some data that they can also help with weight control.

      Apple cider vinegar, as long as it is from a reputable source and consumed in moderation, can be healthy. There is a published case report in the medical literature of severe complications from taking 250 mL of apple cider vinegar every day for 6 years.