Gut Microbiota and Obesity

 My name is Octavia Pickett-Blakely. I'm a board-certified gastroenterologist and I have a subspecialty practice in nutrition and obesity. I'm here to talk to you today about the association between the gut microbiota and obesity. 

In an effort to understand the mechanisms that are contributing to the global obesity pandemic, a large amount of research has been focused on the gut microbiota. Studies have shown that the gut microbiota play an important role in obesity, and specifically, that the gut microbiota play an important role in energy homeostasis, which we know is abnormal in obesity.

The gut microbiota first play a role in carbohydrate metabolism in a process called the carbohydrate salvage. This process is where bacteria metabolize carbohydrates and ferment them into smaller sugars and short-chain fatty acids. The smaller sugars, such as monosaccharides, are readily absorbed in the small bowel and can be processed as stored energy.

The carbohydrate salvage also produces short-chain fatty acids, which are highly involved in energy metabolism. For example, acetate leads to lipogenesis and cholesterol synthesis in the liver. Propionate is associated with gluconeogenesis and cholesterol synthesis regulation in the liver. 

Butyrate can stimulate receptors on the surface of enteroendocrine cells and adipose tissue that, in some instances, increase the production of satiety-producing hormones, and in other instances, can increase nutrient absorption. The gut microbiota are also involved in bile acid metabolism that's important for dietary fat digestion. 

We know that, in states of obesity, the gut microbiota composition is altered. That leads to a change in the gut-derived signaling molecules, like bile acids and short-chain fatty acids, that shift energy homeostasis toward more energy intake, lipogenesis, gluconeogenesis, and a reduction in energy expenditure through reduced thermogenesis and beta-oxidation. 

The studies are ongoing, but it's really important to recognize the role of the gut microbiota in obesity and to encourage your patients to engage in healthy lifestyles, such as diets that are well balanced and rich in fiber, fruits, and vegetables and low in processed and ultraprocessed foods. 

In addition, limiting the excessive and unnecessary utilization of antibiotics can also reduce a person's risk of altering their gut microbiota.

Octavia Pickett-Blakely, MD, MHS

Associate Professor of Clinical Medicine, Department of Medicine, Division of Gastroenterology and Hepatology, University of Pennsylvania Perelman School of Medicine; Director, GI Nutrition, Obesity and Celiac Disease Program, Perelman Center for Advanced Medicine - Penn Medicine, Philadelphia, Pennsylvania

Disclosure: Octavia Pickett-Blakely, MD, MHS, has disclosed the following relevant financial relationships:  
Serve(d) as a director, officer, partner, employee, advisor, consultant, or trustee for: Novo Nordisk  
Serve(d) as a speaker or a member of a speakers bureau for: Institute for Medical and Nursing Education  
Received research grant from: ProventionBio; VectivBio

https://www.medscape.com/viewarticle/association-between-gut-microbiota-and-obesity-2025a1000178