Nav: Home

Altered microbiome burns fewer calories

December 14, 2015

The link between the gut microbiome and obesity seems clear, but just how changes to gut bacteria can cause weight gain is not.

A new University of Iowa study in mice shows that drug-induced changes to the gut microbiome can cause obesity by reducing the resting metabolic rate - the calories burned while sleeping or resting. The findings, published in the journal eBiomedicine, highlight the critical role of gut microbes in energy balance and suggest that unhealthy microbiome shifts can lead to weight gain and obesity by altering resting metabolism.

"Our research leads to the conclusion that it is probably bacteria (in the gut) that are responsible for the calories you burn while you are asleep," says John Kirby, PhD, professor of microbiology and urology at the UI Carver College of Medicine.

Kirby and his colleagues focused on the effects of risperidone, an antipsychotic drug that causes significant weight gain in patients. Risperidone is used to treat various psychiatric disorders in adults and children, including autism, bipolar disorder, and schizophrenia, and prescribing rates for children have increased nearly eight-fold over the last two decades.

In an earlier study, Kirby and Chadi Calarge, a UI pediatric psychiatrist, compared patients taking risperidone long-term to patients who were not on the drug. They found that weight gain was correlated with a significant shift in the composition of the patients' gut microbiomes. These results were published in Translational Psychiatry.

In the new eBiomedicine study, Kirby teamed up with Justin Grobe, UI assistant professor of pharmacology, to find out how this risperidone-induced microbiome shift causes weight gain. Mirroring the human studies, the researchers showed that risperidone causes weight gain in mice (an extra 2.5 grams, or approximately 10 percent of the total body mass, over two months compared to controls) and significantly alters the bacterial composition of the mouse microbiome. They then showed that the altered microbiome causes a reduction in resting metabolic rate that is entirely responsible for the excess weight gain.

"The control mice gain a little weight as they age and their microbiome undergoes a 'healthy shift' due to aging. With the risperidone, the mice become obese and exhibit an alternative, less healthy shift in their microbiome," Kirby says. "With this study, we now have a mechanism for how a shift in the microbiome contributes to weight gain, and it's to do with changes to the resting metabolic rate."

The team was able to investigate how the microbiome shift affected the animals' metabolism by using a novel piece of equipment - a total calorimetry machine - invented by Grobe. The apparatus allows precise measurements of energy intake, oxygen consumption and carbon dioxide output, and heat production in a single animal to determine the total energy change, or "delta G," of the mouse.

The researchers discovered there was no change in aerobic (oxygen-dependent) resting metabolic rate for mice fed risperidone compared to control mice, but there was a significant decrease in non-aerobic resting metabolic rate sufficient to account for the animals' weight gain

"It's about a 16 percent change in resting metabolic rate, which is enormous," Grobe says. "It would be 29 pounds of fat gained every year for an average human."

"That is the equivalent of eating one additional cheeseburger every single day," adds Kirby.

To prove that it was the "shifted" microbiome that was responsible for this metabolic change and the weight gain, the researchers transferred the microbiome from risperidone-fed mice into control mice and saw the same effect: decreased resting metabolic rate and increased weight gain. Moreover, they found it wasn't just the bacteria that could produce this effect. Transferring just the bacteriophage (phage) - viruses that infect the microbiome bacteria -- was sufficient to reduce resting metabolic rate and cause weight gain in control mice.

The results may suggest that manipulating resting metabolic rate, specifically by targeting the gut microbiome, could represent a new approach to treating obesity. Alternatively, preventing unhealthy changes to the microbiome may prove beneficial for patients undergoing risperidone treatment.
-end-
In addition to Kirby and Grobe, the UI research team included first author Sarah Bahr, Benjamin Weidemann, Ana Castro, John Walsh, Orlando deLeon, Colin Burnett, Nicole Pearson, and Daryl Murry.

The study was funded in part by grants from the National Heart, Lung and Blood Institute and the National Institute for Allergy and Infectious Diseases, the American Heart Association, the American Diabetes Association, the National Science Foundation, and the University of Iowa Fraternal Order of Eagles Diabetes Research Center.

University of Iowa Health Care

Related Obesity Articles:

Changing the debate around obesity
The UK's National Health Service (NHS) needs to do more to address the ingrained stigma and discrimination faced by people with obesity, says a leading health psychologist.
Study links longer exposure to obesity and earlier development of obesity to increased risk of type 2 diabetes
Cumulative exposure to obesity could be at least as important as actually being obese in terms of risk of developing type 2 diabetes (T2D), concludes new research published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]).
How much do obesity and addictions overlap?
A large analysis of personality studies has found that people with obesity behave somewhat like people with addictions to alcohol or drugs.
Should obesity be recognized as a disease?
With obesity now affecting almost a third (29%) of the population in England, and expected to rise to 35% by 2030, should we now recognize it as a disease?
Is obesity associated with risk of pediatric MS?
A single-center study of 453 children in Germany with multiple sclerosis (MS) investigated the association of obesity with pediatric MS risk and with the response of first-line therapy in children with MS.
Women with obesity prior to conception are more likely to have children with obesity
A systematic review and meta-analysis identified significantly increased odds of child obesity when mothers have obesity before conception, according to a study published June 11, 2019 in the open-access journal PLOS Medicine by Nicola Heslehurst of Newcastle University in the UK, and colleagues.
Obesity medicine association announces major updates to its adult obesity algorithm
The Obesity Medicine Association (OMA) announced the immediate availability of the 2019 OMA Adult Obesity Algorithm, with new information for clinicians including the relationship between Obesity and Cardiovascular Disease, Diabetes Mellitus, Dyslipidemia, and Cancer; information on investigational Anti-Obesity Pharmacotherapy; treatments for Lipodystrophy; and Pharmacokinetics and Obesity.
Systematic review shows risk of a child developing overweight or obesity is more than trebled by maternal obesity prior to pregnancy
New research presented at this year's European Congress on Obesity (ECO) in Glasgow, Scotland (April 28- May 1) reveals that the risk of a child becoming overweight or obese is more than trebled by maternal obesity prior to getting pregnant.
Eating later in the day may be associated with obesity
Eating later in the day may contribute to weight gain, according to a new study to be presented Saturday at ENDO 2019, the Endocrine Society's annual meeting in New Orleans, La.
How obesity affects vitamin D metabolism
A new Journal of Bone and Mineral Research study confirms that vitamin D supplementation is less effective in the presence of obesity, and it uncovers a biological mechanism to explain this observation.
More Obesity News and Obesity Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 3: Shared Immunity
More than a million people have caught Covid-19, and tens of thousands have died. But thousands more have survived and recovered. A week or so ago (aka, what feels like ten years in corona time) producer Molly Webster learned that many of those survivors possess a kind of superpower: antibodies trained to fight the virus. Not only that, they might be able to pass this power on to the people who are sick with corona, and still in the fight. Today we have the story of an experimental treatment that's popping up all over the country: convalescent plasma transfusion, a century-old procedure that some say may become one of our best weapons against this devastating, new disease.   If you have recovered from Covid-19 and want to donate plasma, national and local donation registries are gearing up to collect blood.  To sign up with the American Red Cross, a national organization that works in local communities, head here.  To find out more about the The National COVID-19 Convalescent Plasma Project, which we spoke about in our episode, including information on clinical trials or plasma donation projects in your community, go here.  And if you are in the greater New York City area, and want to donate convalescent plasma, head over to the New York Blood Center to sign up. Or, register with specific NYC hospitals here.   If you are sick with Covid-19, and are interested in participating in a clinical trial, or are looking for a plasma donor match, check in with your local hospital, university, or blood center for more; you can also find more information on trials at The National COVID-19 Convalescent Plasma Project. And lastly, Tatiana Prowell's tweet that tipped us off is here. This episode was reported by Molly Webster and produced by Pat Walters. Special thanks to Drs. Evan Bloch and Tim Byun, as well as the Albert Einstein College of Medicine.  Support Radiolab today at Radiolab.org/donate.