Can you lose weight by taking prebiotics?

Last Tuesday, my horrified dad called me and told me to take down my "poop transplant" post because he thought it was disgusting and not a funny joke. I told him I wasn't joking. I really wasn't!

But, for those of us who prefer not to put other people's poop into our bodies just yet, is there another way to change our own bowel flora to create a microbiome that could help promote weight loss?

The research is still in it's infancy, really, but several studies have shown that diets with a high amount of fiber (mostly from fruits, vegetables, legumes, and whole grains) are associated with gut flora that do a better job of wasting calories. Prebiotics, which are fiber substances that are indigestible (ultimately reaching the colon where they are fermented by the gut bacteria there), help stimulate the beneficial bacteria. They are found naturally in foods like wheat, asparagus, Jerusalem artichokes, garlic, onions, leeks, and chicory root, and also come in supplements (e.g., the fiber contained in Metamucil Clear & Natural is inulin, which is the fiber derived from chicory root). They can stimulate the "good" bacteria, but can they help abolish the calorie-hoarding bacteria that are found in the colons of obese people, and actually help with weight loss?

As I mentioned last week, there have been studies that have demonstrated that obese people have higher Firmicutes (which have been shown in mice to be better at energy-harvesting -- or keeping calories in the body and increasing fat [1]) and fewer Bacteroidetes in their systems than lean people. What is notable is that these alterations can be abolished after a year of diet-induced weight loss, with the degree of change in microbes being proportionate to the amount of body fat lost [2].
Now the question for future research in humans is whether giving obese people prebiotics that will help people lose more weight than they would lose otherwise just from calorie restriction or increased exercise. It's hard to separate the effect, because many of the foods that people eat when they are trying to lose weight are vegetables that naturally contain prebiotics, so researchers might need to provide one group of dieters a prebiotic in a supplement form while the other dieters get a placebo to see whether there is a difference in weight loss. A promising preliminary study just published in Gut found that obese women who were given a prebiotic supplement containing inulin and oligofructose for 3 months (vs. placebo) had subtle changes in their gut bacteria that could impact obesity and/or diabetes [3]. Now, longer-term studies are needed to evaluate whether prebiotic supplements could actually lead to long-term weight loss and perhaps help prevent the development of diabetes.


References

1. Turnbaugh, P.J., Ley, R.E., Mahowald, M.A., Magrini, V., Mardis, E.R., and Gordon, J.I. (2006). An obesity-associated gut microbiome with increased capacity for energy harvest. Nature 444, 1027–1031.

2. Ley, R.E.; Turnbaugh, P.J.; Klein, S.; Gordon, J. Microbial ecology: Human gut microbes associated with obesity. Nature 2006, 444, 1027–1031.

3. Dewulf, E. M., Cani, P. D., Claus, S. P., Fuentes, S., Puylaert, P. G., Neyrinck, A. M., . . . Delzenne, N. M. (2013). Insight into the prebiotic concept: Lessons from an exploratory, double blind intervention study with inulin-type fructans in obese women. Gut, 62(8), 1112-1121. doi:10.1136/gutjnl-2012-303304; 10.1136/gutjnl-2012-303304
 

Want to lose weight? Get a poop transplant.

OK, so maybe the title of this week's post is a bit sensationalistic, but the future of medicine may truly lie in the transfer of beneficial bacteria from a healthy person's colon into the colon of a person afflicted with a disease or illness -- one of which is obesity. This general idea isn't exactly new, as doctors have been performing fecal transplants for a particular type of infectious diarrhea that we call "C. diff colitis" (because the infection is caused by the overgrowth of a bacterium called Clostridium difficile) for decades with dramatic success.

In a 2006 landmark paper in Nature, Turnbaugh et al. described the differences in gut bacteria (or the "microbiome") of obese vs. healthy mice as well as obese vs. healthy humans, and found that the obese mice and people had an abundance of bacteria that were found to have an increased ability to absorb energy from the diet (meaning, they help the person absorb all the calories eaten rather than lose some of the calories that would've otherwise been indigestible).
http://www.nature.com/nature/journal/v444/n7122/full/nature05414.html
What was striking, though, was that the investigators took the bacteria from the obese or thin mice and transplanted them into the colons of bacteria-free mice, and found that the recipients of the bacteria from obese mice soon gained significantly more fat than the bacteria-free mice who received a stool transplant from the thin mice. This showed that the bacteria could actually CAUSE weight gain rather than just happened to be associated with weight gain.

There have since been scores of fascinating studies that are being done to evaluate the human microbiome, how it affects our health, and how we might be able to manipulate it to help treat medical conditions and diseases -- including obesity. If you've been struggling to lose weight with little success, is a poop transplant in your future?

Is obesity contagious?

You might've heard news reports that obesity might be contagious. What's all this about?

A study published in the New England Journal of Medicine a few years ago followed over 12,000 people for 32 years to help determine whether being socially linked to someone was a more important determinant of developing obesity than being genetically or geographically linked: 

http://www.nejm.org/doi/full/10.1056/NEJMsa066082

The study found that if your friend becomes obese, you have a 57% higher chance of becoming obese yourself (and if you are close/mutual friends, your risk increases to a whopping 171% higher than strangers!).

They also found that next door neighbors' obesity did NOT increase your risk of gaining excessive fat yourself, and that good friends who are very far away geographically still DO increase your risk of gaining weight. This helps rule out exposure to something in the environment (like a virus or a poison) as an explanation, and suggests that it is a change in your thought processes -- in your perception of social norms

and the acceptability of obesity -- that is to blame.

What does this all mean? If you are more likely to gain weight when you have friends who gain weight, then it is reasonable to assume that surrounding yourself with healthy-weight friends may keep you from gaining eight yourself. This can have enormous implications on the obesity epidemic in America. Public health programs

might focus more on weight loss programs that include peer support, since both bad and good behaviors

might spread over social ties/friendships.

The bottom line: if you want to maximize your chances of losing weight and keeping it off, surround yourself with like-minded people. Join a weight-loss community, such as Overeaters Anonymous or Weight Watchers, or start your own fat burners' club at work. Spending too much time with friends who are overweight and who continue to eat unhealthfully and remain sedentary might influence you without you realizing it. Try to spend a little more time with people who make healthy eating choices and get out there and exercise with you!

Who am I??

Who am I?
I am a doctor.
Double board certified in obesity medicine as well as internal medicine, I have been practicing for over 20 years now. The George Washington University Medical Center was home -- I went through medical school and residency training there; I was honored to be asked to serve as Chief Medical Resident and delighted to be inducted into the Alpha Omega Alpha medical honor society there before moving to California in 2003 to join the medical faculty at the University of California San Diego. I was an Assistant Clinical Professor of Medicine at UCSD for four years, caring for patients and teaching medical students and residents. In 2007 I had the opportunity of a lifetime: I moved to Los Angeles to work with Dr. Rob Huizenga and serve as a medical consultant for NBC’s hit reality TV show, “The Biggest Loser.” My time in Los Angeles was spent watching over the contestants during their weight loss journey, making appearances on the show, writing a blog about the behind-the-scenes medical aspects of the show for NBC.com called "Dr. Jen's Journal," and running a private weight loss group in Beverly Hills with Dr. Huizenga. After three seasons of filming the show, Dr. H asked me to buy into his practice and stay on permanently, so I was forced to choose between staying in Hollywood long-term and returning home, and there's just no place like home. I decided to return to academia and relocated back to the DC area in 2008, where I am currently Assistant Professor of Medicine at two medical schools: the George Washington University, and the Uniformed Services University of the Health Sciences. I’m on staff at the Washington DC VA Medical Center, caring for our nation’s heroes and running our medical weight management clinic and bariatric surgery program. I’m passionate about helping others learn to manage their weight as successfully as I have. Weight management is sometimes a meandering road, but staying the course (with occasional course corrections!) will get you there eventually.

I am an obesity survivor. 
I understand weight-related issues better than anyone, having struggled with my own obesity since childhood; my weight topped at about 300 pounds in college. I lost over 120 pounds during medical school and kept it off for 3 or 4 years, but the weight gradually crept back on through the stress of residency, a cross-country move, and a less-than-successful first marriage as I allowed my iron will to relax just a bit. What began as gaining "just 5 or 10 pounds" kept recurring, and gradually 5 or 10 pounds turned into the whole 120: by 2005 I was back to my original 270 pounds. Then in 2006, I applied to be one of the 50 contestants on Season 3 of "The Biggest Loser." I was chosen to represent the state of Virginia, and managed to re-lose 108 pounds in just 8 months as an at-home contestant. Yes, those of us who had to lose weight on our own at home seemed to do as well as those who stayed on the ranch and worked tirelessly with the trainers! Since the show's finale in December 2006, I have successfully maintained my weight loss — with a blip of moderate regain during pregnancy and nursing! — and, believe it or not, I am currently 25 pounds LIGHTER than I was when I appeared on the finale of my season of the Biggest Loser 13 years ago!

I am an investigator.
As a physician-scientist, searching out scientific and medical studies to use as evidence to back up my medical decision-making is critical. We are held to this standard in practice and I have become adept at evaluating potential treatments systematically and critically, using the medical literature to lend scientific proof to my therapeutic decisions. I went back to school while working full time and got a Master's degree in Clinical and Translational Research to help me hone my skills in medical research, and had the opportunity of a lifetime to work with Dr. Kevin Hall at the National Institutes of Health investigating the long-term changes in weight and metabolism of a few of my Biggest Loser compatriots, the season 8 contestants. Our research was widely publicized and I have since been interviewed by various media such as Psychology Today, NPR and the New York Times… with a few more articles here and here.
I’m hoping this blog will serve to help me distill the current scientific literature and come up with new ideas and questions to pursue, and more importantly, disseminate whatever insights I gain to the general public. I want to help you outsmart your stomach just like I have! And maybe tell a few stories and opinions from my life and experiences while I’m at it. Care to join me?