Why some people gain weight eating the same food | Dr Karen Corbin

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Jan 19, 2026

Dr. Karen Corbin, a registered dietitian and expert in nutrition and the gut microbiome, dives into how gut microbes can influence calorie absorption. She reveals that diet composition affects energy balance and discusses the fascinating concept of 'lost' calories due to fecal energy loss. Karen offers practical dietary tips to enhance microbiome health, emphasizes the importance of fiber, and clarifies the differences between probiotics and prebiotics. She also touches on future microbiome research and the potential of diet in personalizing metabolic health strategies.

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INSIGHT

Calories At The Mouth Aren't Final

The calories on food labels ignore how gut microbes ferment undigested food in the colon.
That microbial activity can change how many calories a person actually absorbs from the same food.

INSIGHT

Small Daily Deltas Add Up

Diet can shift daily absorbed energy by meaningful amounts; the study found an average 116 kcal/day difference.
Over months and years, that delta accumulates and could affect body weight and metabolic health.

ADVICE

Feed Microbes To Reduce Absorbed Calories

Design diets to either 'starve' or 'feed' the gut microbiome to test absorption differences.
To reduce absorbed calories, include foods that reach the colon and feed microbial fermentation.

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Could your gut microbiome influence how many calories you absorb from the same food? Karen Corbin explains the science behind energy absorption, faecal calorie loss, and why feeding your microbes may support metabolic health.

We also cover practical diet upgrades, the reality on probiotics, and where microbiome research is heading next, including metabolite signatures and gut–brain links.

What We Cover

How the microbiome may change calorie absorption and energy balance
Why fibre and resistant starch matter, and how to increase them
Where “lost” calories go, and what microbial biomass could mean
Probiotics vs prebiotics: what is worth your time and money
How fast microbiome changes can happen with diet
The future: metabolites, objective diet measures, and brain health research

Thanks for listening. If you enjoyed it, share the episode and subscribe for more evidence-based conversations.

You can keep up with Dr Karen Corbin’s latest research by connecting with her on LinkedIn and exploring her profile at the AdventHealth Research Institute.

Intro (00:00)
Can the Gut Microbiome Increase or Reduce Calorie Absorption? (01:02)
Karen Corbin’s Microbiome Research Journey in Nutrition Science (04:17)
New Microbiome Experiments That Could Change How We Eat (11:17)
Energy Balance Explained: Calories, Metabolism, and Weight Gain (18:28)
How Scientists Study the Gut Microbiome (29:19)
Is the Gut Microbiome Causing Obesity and Metabolic Disease? (38:54)
How Medications Like Metformin Affect the Gut Microbiome (43:31)
Can a High-Fiber Microbiome Diet Reduce Hunger and Cravings? (45:06)
Liver Fat, Type 2 Diabetes, and Metabolic Dysfunction Explained (50:44)
Best Diet and Nutrition Strategies for Fatty Liver Disease (56:01)
How Diet Changes the Gut Microbiome and Metabolism (1:02:27)
Probiotics vs Prebiotics: What Actually Improves Gut Health? (1:07:08)
GLP-1 Weight Loss Drugs and Their Effects on the Microbiome (1:13:07)
Gut Microbiome Metabolites and How They Impact Health (1:16:28)
Gut-Brain Connection: How the Microbiome Affects the Brain (1:21:57)
Future of Gut Microbiome Research and Personalized Nutrition (1:30:24)

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