With rising obesity, microbiomes tip the scale

Human beings have grappled with obesity for thousands of years.

Greek philosopher and physician Galen described “bad humors” as the cause of obesity and prescribed low-calorie foods, massages, baths, greens and garlic to his patients to help them slim down. In the 18th century, William Banting successfully lost weight following a low-carb diet and spread his mantra to the public in a pamphlet called a “Letter on Corpulence,” which sold faster than chocolates. In June 2013, the American Medical Association passed a Resolution 420 declaring obesity as a disease, paving the way for treatment reimbursement.

All the while, health care providers have been intimately trying to find an etiology and a cure for this common but complex condition. Treating obesity has become a multi-billion dollar business; as its incidence and prevalence grows, so too does the bank accounts of investors trying to market the next miracle cure.

Common treatments for obesity include conventional diets such as Atkins, Ornish and the Zone. Pharmacotherapy is another option that invariably comes with a host of side effects. Bariatric surgery remains an effective therapeutic option for those with morbid obesity and associated disorders, but it is expensive, good for only a select group of patients and, of course, surgeon-specific. Ultimately, we need a more sustainable cure the current obesity epidemic.

In the U.S., over a third of the adult population is medically obese, a gateway condition to many other associated diseases and chronic conditions that would not be as prevalent among a healthy-weight population.

Coronary heart disease, type II diabetes, stroke, osteoarthritis, certain cancers and depression are just a few of the health problems that make obesity a double whammy for those that suffer from it.

Obesity also carries grave financial consequences. In fact, according to recent studies, the estimated annual health care costs of obesity-related illness in the U.S. are upwards of $200 billion, and that doesn’t include the costs of disability and unemployment benefits for those too ill to work.

Being obese used to be chocked up to weakness in character and lack of self-control, however, now, it is seen as a condition that has everything to do with societal influences. As sentiments have evolved, people are recognizing that being obese is not entirely due to overeating; it can be an influence of the kinds of foods we eat, increasing sedentary lifestyles, as well as genetic predisposition.

Now more than ever, we live in a society where high-processed fat, high-sugar foods are the most readily available and affordable choices, and children have easy access to simple carbohydrates such as soda and candy at school and home.

In an effort to reduce obesity, there have been recent initiatives to remove junk food from schools, educate children about healthy eating, and incentivize adults to get regular exercise, which are showing promising results. Yet the medical community is still looking at stubborn obesity numbers.

Fresh studies indicate that the underlying cause of obesity may be hidden inside the mysterious landscape of the human gut microbiome. For years, researchers suspected that what goes on in the gut may be a blueprint for overall health.

The etiology of obesity and associated disorders is multifactorial, and of course, diet plays an important role. But the literature has compelling evidence that the microbiota in the human gut acts as a key player in the development of metabolic diseases such as obesity.

A case study published in 2015 underscores the role of the gut microbiome in obesity. In this study, researchers discuss the case of a 32-year-old woman who received fecal microbiota transplant (FMT) to treat recurrent C. difficile infection. While her C.Diff resolved, post-FMT she steadily gained weight and her BMI went up to 33. She was now considered obese, though she was never prior to the FMT. The researchers raise the possibility that the microbiota of the donor, her healthy but overweight teenage daughter, was a contributing factor to her weight gain. In addition, the patient received multiple antibiotics prior to the FMT which may have altered her gut microbiome.

Vandana Nehra, MD, a Mayo Clinic gastroenterologist, shares this theory. “Gut bacteria have the capacity to break down complex food particles, which provides us with additional energy. And this is normally good for us,” she said. “However, for some individuals trying to lose weight, this process may become a hindrance.”

With that in mind, Drs. Kashyap, Nehra and their colleagues decided to test the behaviors of specific bacteria that may be responsible for preventing some individuals from losing weight.

The Mayo Clinic research team collected and analyzed samples from a group of 26 participants enrolled in the Mayo Clinic Obesity Treatment Research Program. The results indicated that gut bacteria among patients who did not lose weight differed from gut bacteria in patients who did lose weight.

The study revealed that the bacteria Phascolarctobacterium was associated with success, while the bacteria Dialister was associated with difficulties to losing weight. “This suggested to us that gut bacteria may possibly be an important determinant of weight loss in response to diet and lifestyle changes,” Dr. Kashyap says.

But can we actually go in an alter the gut microbiome of an obese person?

One of the major factors affecting the composition and diversity of an individual’s intestinal microbiota is diet. This is a good thing because diets can be changed! The food that we eat is populated with its own microorganisms. Thus, our gut microbiome can be altered by changing eating habits and modifying dietary components.

Studies have been conducted comparing the gut microbiomes of populations who had culturally different eating habits and, not surprisingly, the results indicated different strains of bacteria were present. Such differences are vegetarian versus meat-based diets and whole food consumption versus processed foods.

The key is knowing what a healthy microbiome looks like. It is quite possible that with further research, obesity can be stopped in its tracks before individuals who are born predisposed become unable to control their weight through diet alone.

Locating the reasons for chronic obesity are more important than ever before. If we can understand how to alter the gut microbiome, early treatment will be possible — and the future health complications of chronic obesity can be avoided.

Mitra Rangarajan is a nurse practitioner specializing in gastroenterology.  She can be reached at her self-titled site, Mitra Rangarajan.

Image credit: Shutterstock.com

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