Good fats vs. bad fats: New study reveals how the body processes them differently

02/12/2026 / By Belle Carter

Bile acids, produced in the liver, act as gatekeepers, breaking down dietary fats for absorption while selectively favoring beneficial fats (like polyunsaturated fats) over harmful saturated fats.
Researchers used CRISPR to disable CYP7A1 (a bile acid-producing enzyme) in mice, reducing bile acids by 50%. This led to less fat absorption without increased hunger – unlike fat-blocking drugs like orlistat.
Reduced bile acids triggered higher levels of GLP-1 (a satiety hormone), mimicking the mechanism of weight-loss drugs like Ozempic, suggesting a natural appetite-regulating pathway.
Certain bile acids, like cholic acid (CA), were found to be critical for absorbing saturated (“bad”) fats. Manipulating bile acids could allow preferential absorption of healthier fats while excreting harmful ones.
The study opens doors for targeted bile acid treatments to combat obesity, diabetes and metabolic disorders without the drawbacks of current broad-spectrum fat-blocking drugs. Future research aims to develop precision therapies based on these findings.

For decades, dietary guidelines have distinguished between “good fats” (like monounsaturated and polyunsaturated fats) and “bad fats” (such as saturated fats), linking them to heart health, obesity and metabolic disease. But how exactly does the body process these fats differently?

A groundbreaking study led by Dr. Thomas A. Vallim at UCLA, published in Cell Metabolism, reveals that bile acids play a key role in selectively absorbing beneficial fats while excreting harmful ones. The findings could pave the way for new treatments for obesity, diabetes and metabolic disorders.

As explained by BrightU.AI‘s Enoch, bile acids are liver-produced compounds that emulsify fats for digestion and act as signaling molecules influencing gut microbiota and metabolism.

Bile acids: The gatekeepers of fat absorption

Fat is essential for survival and humans have evolved highly efficient ways to absorb it. Bile acids, detergent-like molecules produced in the liver, break down dietary fats into tiny droplets for absorption in the intestines. While this adaptation helped our ancestors survive food scarcity, it contributes to metabolic diseases in today’s fat-rich Western diet.

Vallim’s team sought to understand how bile acids regulate fat absorption, specifically, whether they could be manipulated to favor “good fats” over harmful ones. Using CRISPR gene editing, researchers disabled CYP7A1, a key enzyme for bile acid production, in adult mice. The result? A 50% reduction in bile acids and a surprising metabolic advantage.

A surprising link to weight loss hormones

Mice with reduced bile acids absorbed less fat, but unlike those treated with the fat-blocking drug orlistat (marketed as Alli), they didn’t compensate by eating more. Instead, they showed higher levels of glucagon-like peptide-1 (GLP-1), a hormone that suppresses appetite—the same mechanism behind weight-loss drugs like Ozempic and Wegovy.

“We think fats traveling further into the gut stimulate receptors that promote GLP-1 secretion,” Vallim explained. “It’s like your body saying, ‘I’ve had enough.'”

Further analysis revealed that bile acid reduction didn’t just decrease fat absorption – it selectively allowed beneficial polyunsaturated fats to be absorbed while excreting harmful saturated fats. This distinction was absent in orlistat-treated mice, which indiscriminately blocked all fats, leading to metabolic stress.

Why not all bile acids are created equal

The study also challenged the assumption that fat absorption is a passive, uniform process. By testing different bile acids, researchers found that cholic acid (CA) was crucial for saturated fat absorption, removing it reduced bad fat uptake while preserving good fat absorption.

“This shows that different fats are absorbed differently, and bile acids are the key,” said Dr. Alvin P. Chan, a co-author. “By manipulating bile acids, we can potentially control absorption.”

This research reshapes our understanding of fat metabolism, suggesting that targeted bile acid therapies could help combat obesity and metabolic diseases without the drawbacks of current treatments. The team is now exploring potential drug developments based on these findings.

“The implications are huge,” Vallim said. “If we can fine-tune bile acids, we might unlock new ways to improve metabolic health.”

For a world grappling with rising obesity rates, this study offers a promising, and scientifically nuanced, path forward.

Watch the video below that talks about simple steps in fixing digestive problems.

This video is from the Healing the Body channel on Brighteon.com.