What Does Your Gut Microbiome Have to Do With Obesity, GLP-1s & Bariatric Surgery?

What Does Your Gut Microbiome Have to Do With Obesity, GLP-1s & Bariatric Surgery?

Can your gut microbiome affect obesity, weight loss, GLP-1 medications, or metabolic & bariatric surgery outcomes? And can what you eat actually change how many calories your body absorbs?

In this episode of Weight & Measure with Mike and Zach, we sit down with Karen D. Corbin, PhD, RD, Associate Investigator at AdventHealth Translational Research Institute, for a deep dive into the rapidly evolving science of the gut microbiome, obesity, metabolism, GLP-1 based medications, and metabolic & bariatric surgery.

Dr. Corbin starts with the basics: What is the gut microbiome? Is there actually such a thing as “good” and “bad” gut bacteria? What makes a microbiome healthy? And how do diet, fiber, resistant starch, genetics, hormones, environment, and medications shape the trillions of microorganisms living in our gut?

Then we get into the obesity science.

Dr. Corbin explains research examining how the gut microbiome may influence energy balance and calorie absorption, including her team's controlled feeding study comparing a Western diet with a “microbiome enhancer diet.” Participants eating the microbiome-focused diet absorbed, on average, 116 fewer calories per day, with some individuals showing substantially larger differences in unabsorbed energy.

We also explore the questions many people using obesity treatments are asking:

Does your gut microbiome change when you take a GLP-1 medication? Could your microbiome influence how well a GLP-1 works? Why do two people taking the same medication sometimes experience different weight-loss responses? What happens to the microbiome after sleeve gastrectomy, gastric bypass, or other metabolic & bariatric surgery?

Dr. Corbin explains why much of the research connecting GLP-1 medications and the microbiome still comes from animal models, what scientists need to demonstrate in humans, and why separating the effects of medication, weight loss, diet, GI transit, and metabolic improvements is so difficult.

We also tackle the idea of “GLP-1 receptor sensitivity.” Is GLP-1 resistance actually an established phenomenon? Could genetic differences in the GLP-1 receptor affect treatment response? And have supplements and gut-health products gotten ahead of the science by adding “GLP-1” to their marketing?

Plus, Dr. Corbin busts a major probiotic myth and explains why adding a handful of bacterial species isn't the same thing as rebuilding an incredibly complex microbial ecosystem.

• What the gut microbiome actually is
• “Good” vs. “bad” gut bacteria
• What makes a healthy microbiome
• How food and nutrition shape gut bacteria
• Fiber, resistant starch, whole foods, and ultra-processed foods
• The gut-brain axis, hunger, satiety, and naturally produced GLP-1
• Gut bacteria, calorie absorption, and energy balance
• The microbiome and obesity
• GLP-1 medications and gut microbiome changes
• Why GLP-1 response varies between people
• GLP-1 receptor sensitivity and genetics
• The microbiome after metabolic & bariatric surgery
• Sleeve gastrectomy and gastric bypass
• Probiotics and microbiome myths
• What gut-health science can and cannot tell us today
• How to support your microbiome with food
• Where microbiome and obesity research goes next

One of the most important takeaways: an association between the microbiome and a disease does not necessarily mean the microbiome caused it. The science is promising, but there is still much researchers don't understand.

As Dr. Corbin puts it, one practical question we can ask ourselves is: “Have I fed my gut microbiome today?”

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