Focusing on the 'obesity paradox' to improve cancer treatment success
· Medical Xpressedited by Sadie Harley, reviewed by Robert Egan
Sadie Harley
Scientific Editor
Meet our editorial team
Behind our editorial process
Robert Egan
Senior Editor
Meet our editorial team
Behind our editorial process Editors' notes
This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:
fact-checked
peer-reviewed publication
trusted source
proofread
The GIST Add as preferred source
In research published in the journal Nature, McGill University researchers looked at the relationship between diet, the gut microbiome and patient response to immune checkpoint blockade. To their surprise, certain diets often considered "unhealthy" or "fattening" were associated with better responses to a type of cancer immunotherapy.
"There is a synergistic relationship between the bacteria that reside in our GI tract and the food we eat," said Daniela Quail, associate professor in the Department of Physiology and principal investigator at the Rosalind & Morris Goodman Cancer Institute.
"Even with the right composition of bacteria in your gut, the foods you eat to nourish those populations can determine whether you respond to treatment," said Quail, who co-led a team investigating how diet could affect the success of immune checkpoint inhibitors, a common form of immunotherapy. Other senior members of their team included McGill researcher Logan Walsh and CR-CHUM collaborators Bertrand Routy and Arielle Elkrief.
"Our findings were surprising because they highlighted a benefit of some obesogenic diets," she said. "That tells us the relationship between diet and cancer treatment is more complex than a simple message to eat healthy and exercise."
The findings do not mean people with cancer should adopt diets associated with weight gain, which carries well-known health risks. Instead, researchers hope to find out what is driving the effect on the gut microbiome, the trillions of bacteria that live in the digestive tract, and harness it to improve treatment.
New insights into 'obesity paradox'
The study was inspired by a puzzling phenomenon known more broadly as the "obesity paradox." While obesity is generally associated with higher cancer incidence and mortality, several studies have shown that cancer patients with a higher body mass index (BMI) often respond better to immune checkpoint inhibitors.
By testing 12 different diets in mice, researchers found that some diets associated with obesity improved immunotherapy responses, even after shorter exposure times.
The findings help explain an emerging mystery in cancer research, suggesting the link between obesity and immunotherapy may have less to do with body weight than previously thought and more to do with how diet and gut bacteria work together to influence the immune system.
Publication details
Lysanne Desharnais et al, Diet–microbiome synergy underlies obesity-associated immunotherapy efficacy, Nature (2026). DOI: 10.1038/s41586-026-10750-x
Journal information: Nature
Key medical concepts
Flora, IntestinalCheckpoint Blockade, ImmuneObesity
Clinical categories
OncologyDigestive healthWeight management Provided by McGill University Who's behind this story?
Sadie Harley
BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →
Robert Egan
Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →
Citation: Focusing on the 'obesity paradox' to improve cancer treatment success (2026, September 30) retrieved 30 September 2026 from https://medicalxpress.com/news/2026-09-focusing-obesity-paradox-cancer-treatment.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.