Obesity constricting airways, impacting breathing

The Hidden Link Between Obesity and Asthma: How Weight Affects Your Breathing

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Discover how obesity can trigger bronchial hyperresponsiveness and what you can do to improve your respiratory health."

Many people consider asthma an essential health problem, not everyone with asthma experiences the same symptoms. Bronchial hyperresponsiveness (BHR), a condition where the airways overreact to triggers, is a key factor. BHR can lead to airway inflammation and remodeling, making breathing difficult. Managing BHR is clinically important because it can increase the risk of developing asthma and chronic obstructive pulmonary disease (COPD).

Obesity has emerged as a significant risk factor for BHR, yet the specifics are still debated. Studies have shown conflicting results, with some finding a clear link between obesity and BHR, while others suggest the connection varies based on gender or other health conditions. Some research even indicates a negative correlation between body mass index (BMI) and BHR, adding to the confusion. These inconsistencies highlight the need for a deeper understanding of how obesity influences airway function and responsiveness.

One possible explanation involves small airway closure, a phenomenon where small airways in the lungs collapse, especially during exhalation. Obesity can reduce functional residual capacity (FRC), the amount of air remaining in the lungs after normal exhalation, making airway closure more likely. When airway closure occurs, it can increase airflow obstruction and BHR. Some studies suggest that airway closure might be a crucial link between obesity and BHR, potentially explaining why previous research has yielded conflicting results.

How Does Obesity Trigger Bronchial Hyperresponsiveness?

Obesity constricting airways, impacting breathing

Researchers at the University of Melbourne investigated the relationship between obesity and BHR in middle-aged adults, utilizing data from the Tasmanian Longitudinal Health Study (TAHS). The study aimed to determine whether factors such as gender or asthma history influence this association and whether airway closure plays a causal role.

The study involved performing an inhalational methacholine (MCh) challenge on a group of middle-aged adults who had previously participated in the TAHS. Here’s a quick breakdown of what they did:

Methacholine Challenge: Participants underwent a test to measure how their airways respond to methacholine, a substance that can trigger airway narrowing.
Data Collection: Researchers gathered information on participants' BMI, asthma status, smoking habits, and other relevant health factors.
Statistical Analysis: The team used statistical models to analyze the data and identify relationships between obesity, BHR, and other variables.

The results of the study shed light on how obesity and asthma interact to affect BHR. Here’s what they discovered:

Taking Control of Your Breathing

The study underscores the importance of maintaining a healthy weight to support respiratory function, particularly for those with asthma. By understanding the mechanisms that link obesity and BHR, we can develop targeted strategies to improve lung health and overall quality of life. If you’re concerned about your weight and breathing, consult with your healthcare provider to explore personalized solutions.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1183/13993003.02181-2016, Alternate LINK

Title: Bronchial Hyperresponsiveness And Obesity In Middle Age: Insights From An Australian Cohort

Subject: Pulmonary and Respiratory Medicine

Journal: European Respiratory Journal

Publisher: European Respiratory Society (ERS)

Authors: John A. Burgess, Melanie C. Matheson, Fei Diao, David P. Johns, Bircan Erbas, Adrian J. Lowe, Lyle C. Gurrin, Caroline J. Lodge, Paul S. Thomas, Stephen Morrison, Bruce R. Thompson, Iain Feather, Jennifer L. Perret, Michael J. Abramson, Graham G. Giles, John L. Hopper, Shyamali C. Dharmage, Eugene H. Walters

Published: 2017-09-01

Everything You Need To Know

What is bronchial hyperresponsiveness (BHR), and why is it important?

Bronchial hyperresponsiveness (BHR) is a condition where the airways overreact to triggers, leading to inflammation and making breathing difficult. It is clinically significant because it can increase the risk of developing asthma and chronic obstructive pulmonary disease (COPD). Managing BHR is crucial for preventing these respiratory conditions.

How does obesity lead to bronchial hyperresponsiveness (BHR)?

Obesity can trigger bronchial hyperresponsiveness (BHR) through several mechanisms, one of which involves small airway closure. Obesity reduces functional residual capacity (FRC), the amount of air remaining in the lungs after normal exhalation, making airway closure more likely. When small airways collapse, it can increase airflow obstruction and BHR, contributing to breathing difficulties.

What is the Tasmanian Longitudinal Health Study (TAHS), and how was it used in the research?

The Tasmanian Longitudinal Health Study (TAHS) is a research initiative that provided data for a study investigating the relationship between obesity and bronchial hyperresponsiveness (BHR) in middle-aged adults. Researchers utilized data from TAHS to determine whether factors such as gender or asthma history influence the association between obesity and BHR, and whether airway closure plays a causal role.

What is a methacholine (MCh) challenge, and how does it relate to studying asthma and obesity?

The methacholine (MCh) challenge is a test used to measure how the airways respond to methacholine, a substance that can trigger airway narrowing. In the context of the study, participants underwent an inhalational MCh challenge to assess their bronchial hyperresponsiveness (BHR). This test helps researchers understand the degree to which the airways overreact to stimuli.

What is functional residual capacity (FRC), and why is it relevant to obesity and breathing problems?

Functional residual capacity (FRC) is the amount of air remaining in the lungs after a normal exhalation. In the context of obesity and asthma, obesity can reduce FRC, making small airway closure more likely. Reduced FRC contributes to increased airflow obstruction and bronchial hyperresponsiveness (BHR), impacting overall respiratory function. This is significant because maintaining adequate FRC is essential for efficient breathing.